ME00003B - Perforated microparticles and methods of use - Google Patents

Abstract

Technically manufactured particles for administering a bioactive agent to a patient's respiratory tract are provided. The particles can be used in the form of a dry powder or in the form of stabilized dispersions in the form of a non-aqueous continuous phase. In particularly preferred embodiments, the particles can be used with an inhaler, such as a dry powder inhaler, metered dose inhaler, or mist.

Description

Pronalaska region

This invention relates to preparations and methods for the production of perforated microstructures containing an active agent. In particularly recommended embodiments, the active agent consists of one bioactive agent. Perforated microstructures will be recommended to be used in connection with inhalation devices, such as metered dose inhalers, dry powder or nebulizer inhalers for local or systemic administration via pulmonary or nasal administration.

State of the art

Targeted administration of drugs is especially desirable when the toxicity or bioavailability of the pharmaceutical compound is in question. Specific drug administration procedures and preparations, which effectively deposit the compound at the site of action, potentially serve to minimize toxic side effects, lower dosage requirements, and reduce treatment costs. In this regard, the development of such pulmonary drug delivery systems has long been a goal of the pharmaceutical industry.

The three most commonly used systems, which are used today with the aim of local administration into the pulmonary airways, are dry powder inhalers (DPI), metered dose inhalers (MDI) and nebulizers MDI, the most popular methods of local administration, can be used to administer drugs in dissolved or dispersed form. Tiopic MDIs contain some freon or some other propellant gas of high vapor pressure, which pushes the aerosol drug into the respiratory tract when the device is activated. Unlike MDl, DPIs are usually based on the patient's inhalation effort to introduce the drug in the form of a dry powder into the cork. Finally, nebulizers create a medicated aerosol that is inhaled while adding energy to the liquid solution. More recently, direct administration of drugs during liquid ventilation or lung lavage using a specific fluorochemical medium has been investigated. While each of these procedures and associated systems may prove effective in selected situations, inherent drawbacks, including formulation limitations, may limit their use.

MDI depends on the driving force of the propulsion system, which is used in their production. Traditionally, the propellant system consisted of a mixture of chlorofluorocarbons (CFCs), which were chosen to create the desired vapor pressure while maintaining suspension stability. Currently, freon 11, freon 12 and freon 114 are mostly used as CFCs in aerosol formulations for inhalation. While such systems can be used to deliver a dissolved drug, the selected bioactive agent is typically incorporated in the form of fine particles to create a dispersion. In order to minimize or prevent the problem of agglomeration of such systems, surfactants (means for increasing the surface tension) of bioactive agents are often used, which help wetting the particles with the aerosol propellant. The use of surfactants in such a manner to maintain a substantially uniform dispersion is considered "stabilization" of suspensions.

Unfortunately, traditional chlorofluorocarbons are now considered to deplete the stratospheric ozone layer and, as a consequence, have been phased out. This, in turn, led to the development of aerosol formulations for pulmonary delivery of fluids using the so-called propellants, friendly to the environment. The propellant groups believed to have the least ozone-depleting potential compared to CFCs are perfluorinated compounds (PFCs) and hydrofluoroalkanes (HFAs). While selected compounds from these groups can function effectively as biocompatible propellants, many of these agents, which were effective in stabilizing drug suspensions with CFCs, are no longer effective in new propellant systems. As the solubility of surfactants decreases in HFA, their diffusion in the interspace between drug particles and HFA becomes accordingly too light, which results in poor wetting of drug particles and loss of stability of suspensions. Reduced solubility of surfactants in HFA propellants can easily result in reduced effectiveness of any introduced bioactive system.

More broadly, suspensions of drugs in liquid fluorochemicals, including HFA, form heterogeneous systems, which usually require redispersion before use. However, due to factors, such as the acceptability of the patient who receives a relatively homogeneous distribution of the pharmaceutical compound, which is not always easy or successful, in addition to preparations from the state of the art with the content of very small particles, which tend to clump together, it can result in insufficient administration of the drug. Crystal growth in suspensions, due to Oswold ripening, can also result in heterogeneous particle size and can significantly shorten the shelf life of the preparation. This can occur by a number of mechanisms, including flocculation, fusion, molecular fusion, and caking. During a relatively short time, these processes can solidify the preparation to the point where it is no longer usable. Thus, while conventional systems with fluorine chemical propulsion systems for MDI or liquid ventilation represent a significant improvement over the prior state without fluorine chemical propulsion systems, drug suspensions can be improved to enable the creation of formulations of increased stability, which provide increased stability and also offer more effective and more accurate dosing to the desired place.

Similarly, conventional powder formulations for use in DPI often do not provide accurate, reproducible dosing over extended timeframes. In this regard, those in the field will understand that ordinary powders (ie, those that are completely finely divided) have a tendency to clump together due to hydrophobic or electrostatic interactions between the fine particles. These changes in particle size and increased cohesive forces over time tend to create powders, which give an undesirable distribution of the drug in the lungs after using the device. More closely, the clumping of fine particles disrupts the aerodynamic properties of the powder particles, thereby preventing large amounts of aerosolized drugs from reaching the deeper airways of the lungs, where they are most effective.

With the aim of reducing the unwanted increase in cohesive forces, formulations according to the prior state of the art usually used large carrier particles with lactose content in order to prevent the agglomeration of fine drug particles. Such carrier systems allow at least some drug particles to be loosely bound to lactose particles and to disintegrate upon inhalation. However, a significant part of the drug fails to separate from the large lactose particles and settles in the throat. As such, these carrier systems are relatively inefficient with respect to the fine particulate matter generated by DPI activation. Another solution regarding the aggregation of particles is proposed in WO 98/31346, in which particles of relatively large geometric diameters (ie, preferably larger than 10 pm) are used with the aim of reducing the number of particle interactions, thereby maintaining the fluidity of the powder. As with previous carrier systems, the use of large particles appears to reduce the mean surface area of the powder preparations, resulting in improved flowability and fraction of fine particles. from optimal doses due to potentially longer dissolution times. And so, there is still a need for particles of a standard size, which resist aggregation and retain the fluidity and dispersibility of the resulting powder.

Therefore, the subject of this invention is the creation of procedures and preparations, which enable successful nasal or pulmonary administration of powders consisting of relatively very fine particles.

Another object of this invention is to obtain stable preparations suitable for aerosolization and administration through the pulmonary airways to a patient in need thereof.

Another object of the present invention is to create powders that can be used to create stable dispersions

Then, another object of the present invention is to create powders having relatively low cohesive forces, suitable for use with dry powder inhalers.

Brief description of the invention

These and other objects have been achieved by the invention disclosed herein. To this end, the methods and related preparations provide, in a broader sense, improved delivery of active agents to the desired site. More specifically, the present invention may provide delivery of bioactive agents to selected physiological target sites using perforated microstructured powders. In preferred embodiments, the bioactive agents are in a form for administration to at least one portion of the pulmonary airways of a patient in need thereof. To this end, the present invention enables the creation and use of perforated microstructures and systems for their delivery, as well as their individual components. The published powders can further be dispersed in selected suspensions to create stable dispersions. In contrast to powders from the prior art for drug administration, this invention preferably applies new techniques with the aim of reducing attractive forces between particles. Thus, the published powders show improved flowability and dispersibility, while the published dispersions show reduced degradation due to flocculation, settling or thickening. What's more, the stabilized preparations according to this invention preferably contain a suspension medium (for example, a fluorine chemical substance) which, in addition, serves to reduce the rate of degradation of the contained bioactive agent. Therefore, the dispersions or powders of the present invention can be used with metered dose inhalers, dry powder inhalation nebulizers and/or with liquid dose (LDI) techniques, in order to create effective drug delivery.

In terms of particularly recommended embodiments, hollow and/or porous perforated microstructures significantly reduce attractive molecular forces, such as van der Waals forces, which prevailed in solutions of preparations according to the prior art. In this regard, powder preparations typically have a relatively low bulk density, which contributes to the fluidity of the preparation, while providing the desired person for inhalation therapy. More closely, the use of perforated (or porous) microstructures of relatively low density significantly reduces attractive forces between particles, thereby reducing shear forces and increasing the fluidity of the obtained powders. The relatively low density of perforated microstructures gives better aerodynamic properties when used in inhalation therapy. When in dispersion, the typical characteristics of powders ensure the production of stable preparations. What's more, by choosing the components for dispersions in accordance with the instructions given here, intercellular attractive forces can be further reduced and preparations with even better stability can be obtained.

Therefore, selected embodiments according to the present invention provide powders with increased dispersibility, containing a large number of perforated microstructures, with a bulk density of less than 0.5 g/cm3, wherein said perforated microstructures contain an active agent.

With respect to perforated microstructures, those skilled in the art will understand that they can be formed by any suitable process which provides the desired physical properties or morphology. In this regard, perforated microstructures will preferably contain pores, cavities, cracks or other interstices, which act to minimize surface interactions and shear forces. However, subject to these limitations, it will be clear that any material or shape can be used to form a matrix of microstructures. Regarding the chosen materials, it is preferable that the microstructures contain at least one surfactant. It is recommended that the surfactant contains one phospholipid or another, approved for pulmonary use. Similarly, it is recommended that the microstructures contain at least one active agent, which may be bioactive. In terms of shape, particularly recommended designs include spray-dried hollow microspheres (balls) with a relatively thin porous wall, which includes a large internal cavity, but other shapes with cavities and perforated walls are also taken into account. The recommended versions of the perforated microstructure also contain a bioactive agent.

Therefore, this invention provides the use of a bioactive agent for the production of a drug for pulmonary administration, wherein the drug consists of a large number of perforated microstructures, which are aerosolized using an inhalation device with the aim of creating an aerosolized drug containing said bioactive agent, in which said aerosolized the medicine is given to at least one part of the nasal or pulmonary airway of the patient, who needs it.

It will further be clear that, in selected embodiments, this invention also includes methods for producing perforated microstructures that have improved dispersibility. In this respect, it will be clear that the disclosed perforated microstructures exhibit less attractive molecular forces, such as van der Waals forces, which prevailed in prior art burst preparations. This means that, in contrast to preparations of the prior art, which contained relatively dense, solid particles (i.e. crushed), powder preparations according to this invention show increased fluidity and ability to disperse due to lower shear forces. The reduction of cohesive forces is partly the result of new production procedures of new powders.

As such, preferred embodiments of the present invention provide methods for producing perforated microstructures, which comprise the following steps:

creating a liquid starting material containing an active agent;

scattering of particulate material with the aim of obtaining broken droplets;

drying of the mentioned liquid droplets under predetermined conditions with the aim of forming perforated microstructures containing the active agent; and

collection of the mentioned perforated microstructures.

With regard to the formation of perforated microstructures, it will be clear that, in the recommended implementations, the particles will be dried in a dispersed state using commercially available equipment. In this regard, the starting material will contain one propellant, which is chosen from fluorinated compounds and non-fluorinated oils. It is recommended that fluorinated compounds have a boiling point higher than 80ͦ C. In regard to this invention, the fluorinated propellant can be inside the perforated microstructures with the aim of further increasing the dispersibility of the obtained powder or improving the stability of dispersions in it. Furthermore, non-fluorinated oils can be used to increase the solubility of the selected bioactive agent (eg steroids) in the starting material, which results in an increased concentration of bioactive agents in the perforated microstructures.

As discussed above, the dispersibility of the perforated microstructures can be increased by reducing or minimizing the van der Waals attractive forces between the perforated microstructures used. In this regard, the present invention further provides methods for increasing the dispersibility of the powder, which include:

creating a liquid starting material containing an active agent; and

drying of the mentioned liquid material with the aim of creating perforated microstructures with a volume density of less than about 0.5 g/cm^, whereby the mentioned powder shows reduced van der Waals attractive forces, compared to a relatively non-porous powder of the same composition. In particularly recommended designs, the perforated microstructures will have the form of hollow, porous microspheres.

The propellant can be dispersed into the carrier using methods known in the art to produce homogeneous dispersions, such as noise shielding, mechanical mixing, or high pressure homogemization. Other methods considered for dispersing the propellant into the starting material include mixing the two fluids prior to atomization, as described in the double nebulization process. Certainly, it will be clear that the sprayer can be adapted to optimize the desired characteristics of the particles, such as their size. In special cases, a double liquid nozzle can be used. In another embodiment, the propellant can be dispersed by introducing it into a solution under elevated pressure, as in the case of nitrogen or carbon dioxide.

Regarding the ejection of perforated microstructures or stable dispersions, another aspect of the present invention is directed to inhalation systems for administering one or more bioactive agents to a patient. In this regard, the present invention provides systems for pulmonary delivery of a bioactive agent to a patient, comprising:

inhalation device with tank; and

powder in said reservoir, wherein said powder contains a large number of perforated microstructures with a volume density of less than about 0.5 g/cm3 and the powder composed of perforated microstructures contains a bioactive agent, and wherein said inhalation device provides aerosol administration of said powder at least once part of the patient's pulmonary airways, who needs it. As discussed above in this regard, it will be clear that an inhalation device may consist of a nebulizer, a nozzle, a dry powder inhaler, a metered dose inhaler, or a nebulizer. Moreover, the reservoir can contain individual doses or be shared.

In other embodiments, the powders of the perforated microstructure can be dispersed in a suitable suspension medium to create stabilized dispersions for the delivery of a particular agent. Such dispersions are particularly suitable for metered dose inhalers and nebulizers. In this regard, particularly recommended suspension media include fluorine chemicals (eg, perfluorocarbon or fluorocarbon, which are liquid at room temperature). As stated above, many fluorine chemicals are well known to have proven safety and pulmonary incompatibilities. Furthermore, in contrast to water growth, fluorine chemicals do not adversely affect gas exchange. Moreover, due to their unique wetting properties, fluorochemicals may be able to provide dispersion of particles deeper into the lungs, thereby improving systemic delivery. Finally, many fluorine chemicals also have a bacteriostatic effect, which reduces the possibility of microbial growth in compatible preparations.

Whether administered in the form of dry powder or stabilized dispersions, the present invention provides for efficient delivery of bioactive agents. As used herein, the term "bioactive agent" refers to substances used in connection with an application that is therapeutic or diagnostic in nature, such as procedures for diagnosing the presence or absence of a disease in a patient and/or procedures for treating a patient's disease. As for bioactive agents, those skilled in the art will know that any therapeutic or diagnostic agent can be contained in the stabilized dispersion of the present invention. For example, the bioactive agent can be selected from the group consisting of: antiallergists, bronchodilators, bronchoconstrictors, lung tissue surfactants, analgesics, anticholergetics, the largest number of inhibitors, antihistamines, anti-inflammatory agents, aminoplastics, anesthetics, antituberculins, contrast agents, cardiovascular agents, enzymes, steroids, genetic materials, viral vectors, antidote agents, peptides and their combinations. In preferred embodiments, the bioactive agents will contain compounds, which should be administered systemically (ie into the patient's systemic circulation), as peptides, proteins or polynucleotides. As will be discussed in more detail below, the bioactive agent may be embedded, mixed, coated, or otherwise attached to the perforated microstructures.

Accordingly, the present invention provides methods for pulmonary administration of one or more bioactive agents, comprising:

creating a powder consisting of a large number of perforated microstructures with a volume density of less than about 0.5 g/cm3, wherein said perforated microstructures contain some bioactive agent;

aerosolization of the mentioned perforated microstructures with the aim of obtaining an aerosolized drug; and

administering a therapeutically effective amount of said aerosolized drug to at least one part of the nasal or pulmonary airways of a patient in need thereof.

As used herein, the term "aerosolized" shall mean a gaseous suspension of fine solid or liquid particles, unless otherwise specified by certain limitations. That is, an aerosol or aerosolized drug can be created, for example, by a dry powder inhaler, a metered dose inhaler, a nebulizer, or a nebulizer.

With respect to the disclosed powders, the selected bioactive agent, or agents, may be used as the sole structural component of the perforated microstructures. In contrast, perforated microstructures can contain one or more components (ie structural materials, surfactants, additives, etc.). next to the inserted asset. In particularly recommended embodiments, the suspended perforated microstructures will contain high concentrations of surfactant (greater than 10% by weight), together with the inserted bioactive agent. Finally, it should be clear that the comminuted or perforated microstructures can be coated, bonded or otherwise combined with the bioactive agent in a non-integral manner. Whichever configuration is chosen, it will be clear that each bound bioactive agent can be used in its native form, or in the form of one or more salts known in the art.

While the powders or stabilized dispersions of the present invention are particularly suitable for pulmonary administration of bioactive agents, they can also be used for local or systemic administration of the compound anywhere on the patient's body. Accordingly, it should be understood that, in preferred embodiments, the formulations may be administered using a variety of routes, including, but not limited to, gastrointestinal tract, respiratory tract, topical, intramuscular, intraperitoneal, nasal, vaginal, rectal, through ears, orally or through the eyes.

Other objects, features and advantages of the present invention will be apparent to those skilled in the art from consideration of the following detailed description of preferred embodiments of the invention.

Brief description of the drawing -

SI. 1A1 to 1F2 show changes in the morphology of particles as a function of the change in the speed of blowing with fluorocarbons in relation to phospholipid (PFC/PC), present in the dry matter plant. Fluorographs, recorded with a scanning microscope and the technique of electronic transmission of microscopic images, show that in the absence of FO, or with low PFC/PC ratios, the obtained dried microstructures containing gentamicin sulfate are neither hollow nor porous per se. In contrast, at high PFC/PC ratios, the particles contain numerous pores and are cylindrically hollow with thin walls.

SI. 2 shows the stability of gentamicin particle suspension in Perflubron as a function of PFC/PC ratio or particle porosity. The porosity of the particles increased with increasing PFC/PC ratio. The highest stability was observed at PFC/PC ratios between 3 and 15, which shows the recommended morphology of perflubron suspension media.

S. 3 is a scanning electron microscopic image of perfluorinated microstructures, consisting of cromolyn sodium, showing the preferred cavity/pore morphology.

SI. 4A to 4G are photographs showing the improved stability of dispersions according to the present invention over time compared to a commercial formulation of cromoline sodium (Intal(P), Rhone-Poulenc-Rorer). In these photographs, the commercial formulation on the left disintegrates rapidly, while the dispersion on the right, formed according to these procedures, remains stable over a long period of time

SI. 5 shows the results of in-vitro studies using the Andersen-cascade impactor, in comparison with the same hollow porous formulations of albuterol sulfate, obtained by MDI in HFA. 134e, or using the DPI example. Efficient delivery of particles was observed with both devices. MDI particle delivery is maximized at plate 4, which corresponds to upper airway delivery. DPI delivery of particles results in significant deposition at the later stages of the impactor, corresponding to improved systemic delivery in-vivo.

Detailed description of recommended versions

While the present invention may be embodied in many different forms, a few specific embodiments are disclosed herein, which illustrate the principles of the present invention. It should be understood that this invention is not limited to the specific embodiments shown.

As set forth above, the present invention provides methods, systems, and compositions comprising perforated microstructures that, in preferred embodiments, can be successfully applied to deliver bioactive agents. In particularly recommended embodiments, the published powders of perforated microstructures can be used in the dry state (e.g. as in DPI) or in the form of sterile dispersions (e.g. as in MDI, LDI or in nebulizer mixtures, for the administration of bioactive agents through nasal or patient's pulmonary airways. It will be understood that the disclosed perforated microstructures consist of a single structural matrix that constitutes, defines, or contains cavities, pores, fissures, apertures, spaces, interior spaces, passages, perforations, or holes. Absolute Form (vs. Moprphology) of perforated microstructures is generally uncritical and any average configuration, which provides the desired characteristics, may be considered, from the point of view of being within the scope of the present invention. Accordingly, preferred embodiments may consist of approximately microspherical shapes. deformed or broken particles are also applicable.Under this term, it will further be clear that the recommended embodiments consist of hollow, porous microspheres, spray-dried. In any event, the disclosed powders of perforated microstructures provide certain advantages including, but not limited to, increased stability of suspensions, improved dispersibility, better dosing, elimination of powder collection in corners, and improved aerodynamics.

Those skilled in the art will appreciate that many of these features are particularly useful for dry powder inhalation applications. In contrast to prior art formulations, this invention provides unique procedures and mixtures aimed at reducing cohesive forces between dry particles, thereby minimizing particle agglomeration, which results in improved drug delivery efficiency. As such, the disclosed preparations provide highly flowable dry powders, which are easily aerosolized, uniformly administered, and penetrate deeply into the pulmonary or nasal airways. Moreover, the perforated microstructures of the present invention result in surprisingly little deposition in the throat during administration.

In pre-handiable designs, powders made of perforated microstructures have a relatively low density. which allows the powder to be better dosed compared to preparations according to the previous state of the art. However, as explained above, many commercial formulations of dry powders consist of large lactose particles, which carry micronized drug particles on their surfaces. For these prior art formulations, the lactose particles serve as a carrier of the active agent and as a bulking agent, thereby creating the possibility of partially controlling the amount of drug (dose) given by the device. eat in small doses, adding mass and volume to such a dosage form.

In contrast, the present invention utilizes processes and compositions that yield powder formulations of extremely low bulk density, thereby reducing the minimum charge weight, commercially possible, for use in powder inhalation devices. That is, the majority of single dose vessels designed for DFI are filled using fixed volume or gravimetric techniques. In contrast to prior art formulations, the present invention provides powders in which the active or bioactive agent and other ingredients and fillers constitute the entire inhaled particle. Preoperate according to this. the invention typically provides powders with a bulk density of less than 0.5 g/cm3 or 0.3 g/cm3, preferably less than 0.1 g/cm3, and most preferably less than 0.05 g/cm3. By obtaining particles with a very low volumetric density, the smallest mass of powder that can be filled into a container with individual doses is reduced, which rejects the need for carrier tubes. That is, the relatively low density of the powders according to the present invention allows reproducible administration of relatively small doses of pharmaceutical compounds. What's more, by eliminating the carrier particles, the deposition in the throat and any "choking" effect will most likely be avoided, since large lactose particles hit the wall of the throat and upper airways due to their size.

In accordance with what has been stated here, the recommended microstructures will preferably be produced in a "dry" state. That is, the microparticles will have a moisture content, which will allow the powder to remain chemically and physically stable during storage at room temperature and to disperse easily. As such, the moisture content of the microparticles is typically less than 6% by weight, preferably less than 3% by weight. In some cases, the moisture content will be as low as 1% by weight. Of course it will be clear that the moisture content is, at least in part, dictated by the formulation and governed by the production conditions, eg, inlet temperature, concentration of starting materials, pumping speed and type of propellant, its concentration and subsequent drying.

Regarding preparations with a structural matrix, which defines perforated microstructures, it can be formed from any material that has physical and chemical characteristics, compatible with any incorporated active agent. While a wide variety of materials can be used to form the particles, in particularly preferred embodiments, the structural matrix is associated with, or contains, a surfactant, such as a phospholipid or a fluorinated surfactant. Although not required, the incorporation of a compatible surfactant can improve powder flowability, improve dispersion stability, and facilitate suspension preparation. It will be understood that, as used herein, the term "structural matrix" or "microstructure matrix" is equivalent to and refers to any solid material that forms a perforated microstructure, which defines a large number of cavities, apertures, depressions, pores, furrows, etc., which provide the desired characteristics. In preferred embodiments, the perforated microstructures defined by the structural matrix contain hollow porous microspheres created by grinding in a dispersed state, containing at least one surfactant. It will further be clear that, starting from the components of the matrix, the density of the structural matrix should be adjusted. Finally, which will be discussed in more detail below, perforated microstructures contain at least one active or bioactive agent.

As indicated, the perforated microstructures of the present invention may be associated with, or contain, one or more surfactants. Moreover, mixed surfactants can be used (if they are miscible) in the case where the microparticles are formulated in a suspension liquid medium. It will be clear to those skilled in the art that the use of surfactants, although not necessary for the practice of the present invention, can further improve dispersion stability, powder flowability, simplify the formulation process, or increase administration efficiency. Of course, a combination of surfactants, including the use of one or more in the liquid phase, along with the microstructures, is contemplated within the scope of the present invention. By "in connection with or containing" is meant that the structural matrix or perforated microstructures may contain, adsorb, absorb, be coated, or formed with surfactant.

Broadly speaking, surfactants suitable for use in the present invention include any compound or mixture, which aids the formation of perforated microparticles, or provides improved stability of suspensions, improved powder dispersibility or reduced powder caking. A surfactant can consist of only one compound or any combination of compounds, as is the case with co-surfactants. Particularly recommended surfactants are non-fluorinated ones selected from the group of saturated or unsaturated lipids, non-ionic detergents, non-ionic block copolymers, ionic surfactants and their combinations. In these embodiments, which contain stable dispersions, such non-fluorinated surfactants will be relatively insoluble in the suspension medium. It should be emphasized that, in addition to the mentioned surfactants, suitable non-fluorinated surfactants are compatible with those presented here and can be used to obtain the desired preparations.

Lipids, including phospholipids, both natural and artificial, are particularly compatible with the present invention and can be used in various concentrations to form a structural matrix. Lipids, generally compatible, include those that have a gelled or liquid crystalline phase transition above about 40°C. It is recommended that the lipids used have a relatively long chain (ie C16 - C22) of saturated lipids and even more recommended that they contain phospholipids. Examples of phospholipids suitable for the published stable preparations include dipalmitoylphosphatidicholine, disteroylphosphatidylcholine, diarajidoylphosphatidicholine, dibehenoylphosphatidicholine, short-chain phosphatidicholines, long-chain saturated phosphatidylethaneylamines, long-chain saturated phosphatidylserines, long-chain saturated phosphatidylglycerols, saturated phosphatidylinositols, glycolipids, ganglioside GM-1, sphingomyelin, phosphate acid, cardiolipin; lipids with polymer chains, such as polyethylene glycol, chitin, hyaluronic acid, or polyvinylpyrrolidone lipids with sulfonated mono-, di-, and polysaccharides, and fatty acids, such as palmitic, stearic, and oleic acids; cholesterol, cholesterol esters and cholesterol hemisuccinates Due to their excellent compatibility, phospholipids and combinations of phospholipids and poloxamers are particularly suitable for use in the pharmaceutical preparations discussed herein.

Compatible nonionic detergents include: sorbitan esters, including sorbitan trioleate (Span(R) 85), sorbitan sesquioleate, sorbitan monooleate, sorbitan monolaurate, polyoxyethylene (20) sorbitan monolaurate and polyoxyethylene (20) sorbitan monooleate, oleyl polyoxyethylene (2) ether, stearyl polyoxyethylene (2) ether, lauryl polyoxyethylene (4) ether, glycerol esters and sucrose esters. Other suitable nonionic detergents can be readily identified using McCutcheon's Emulsifiers and Detergents (McPublishing Co., Glen Rock, New Jersey, USA), which is incorporated herein in its entirety. Suitable block polymers include diblock and triblock copolymers of polyoxyethylene and polyoxypropylene, including poloxamer 188 (Pluronic(R) F-68), poloxamer 407 (Pluronic(R) F-127), and poloxamer 338. Ionic surfactants, such as sodium surfactants and fatty acid soaps can also be used. In suitable embodiments, the microstructures may contain oleic acids or their alkaline salts.

In addition to the above-mentioned surfactants, cationic surfactants or lipids are recommended, especially in the case of administration using RNA or DNA. Examples of suitable cationic lipids include: DOTMA, N-(1 -[2, 3-diolyloxypropyl]-N; N; N-trimethylammonium chloride, DOTAP, 1, 2-diolyloxy-3-(trimethylammonio)propane; and DDTB, 1, 2-di-oleyl-3-(4'-trimethylammoniobutenoyl)-ene-glycerol Amino acids such as polysine and polyarginine are also considered.

In addition to the above-mentioned surfactants, it will further be understood that a wide variety of surfactants can be used as desired in connection with the present invention. Moreover, the optimal surfactants or their combination for a given application can be easily determined by empirical studies, which do not require unnecessary experiments. Finally, as will be discussed in more detail below, surfactants encapsulated in a structural matrix may be useful in the formation of precursor oil-in-water emulsions (ie, spray drying feedstock) during the process of forming perforated microstructures.

In contrast to formulations from the prior art, it was surprisingly discovered that the introduction of a relatively large proportion of surfactants (eg, phospholipids) can be used to improve the dispersing ability of the powder, increase the stability of the suspensions and reduce the powder clumping for published applications. This means, on a weight-by-weight basis, the structural matrix of the perforated-microstructures can contain relatively large amounts of surfactants. In this regard, the perforated microstructures contained more than about 1%, 5%, 10%, 15%, 18%, even 20% by weight. of surfactant. More preferably, the perforated microstructures contained more than 25%, 35%, 40%, 45%, or 50% by weight. of surfactants. Some other examples of implementation will be perforated microstructures where there are surfactants more than 55%, 70%, 75%, 80%, 85%, 90% or even 95% by weight. of surfactants. In specially selected designs, the perforated microstructure contained essentially 100% by weight. of surfactants, such as phospholipids. It will be clear to those skilled in the art that in such a case, the balance of the structural matrix (where applicable) will likely consist of a bioactive agent or surface-inactive additive or additives.

While such quantities of surfactants are recommended for use with perforated microstructures, they can be used to obtain stabilized systems with a content of relatively non-porous or essentially full particles. This means that while the preferred embodiments will contain perforated microstructures with a large amount

of surfactants, acceptable microspheres can be obtained using a relatively small proportion of porous participants at the same surfactant concentration (i.e. greater than 20% by weight).

In other recommended embodiments of the invention, the structural matrix, which defines the perforated microstructures, optimally contains synthetic or primary polymers or their combinations. In this respect, useful polymers include polyactides, polyactide-glycolides, cyclodextrins, polyacrylates, methylcellulose, carboxymethylcellulose, polyvinyl alcohols, polyanhydrides, polyactems, polyvinyl pyrrolidones, polysaccharides (dextrose, starches, quinine, chitosan, etc.), hyaluronic acid, proteins (albumin, collagen, gelatin, etc.). Examples of polymer resins that would be useful for preparing perforated microparticles include: styrene-butadiene, styrene-isoprene, styrene-acrylonitrile, ethylene-vinyl acetate, ethylene-acrylate, ethylene-acrylic acid, ethylene-methylacrylates, ethylene-ethyl acrylate. , vinyl-methyl methacrylate, acrylic acid-methyl methacrylate and vinyl chloride-vinyl acetate. It will be clear to those skilled in the art that, by choosing appropriate polymers, the efficiency of administration of perforated microparticles and/or the stability of dispersions can be adjusted in order to optimize the effectiveness of the active or bioactive agent.

In addition to the above-mentioned polymeric materials and surfactants, it may prove desirable to add other additives to the microsphere formulation with the aim of increasing particle hardness, increasing production yield, administration and deposition efficiency, prolonging shelf life and patient acceptability. Such additives optionally include, but are not limited to, flavor enhancers, buffers, hygroscopic agents, antioxidants, and chemical stabilizers. Further, various additives can be included in, or added to, a certain matrix with the aim of obtaining the structure and shape of perforated microstructures (ie microspheres, like latex particles). In this regard, it will be clear that strength enhancing components can be omitted, using post-production techniques such as selective solvent removal.

Other firming agents include, but are not limited to, carbohydrates, including monosaccharides, disaccharides, and polysaccharides. For example, monosaccharides, such as dextrose (anhydrous and monohydrate), galactose, mannitol, D-mannose, sorbose, etc.; disaccharides such as lactose, maltose, sucrose, trehalose, etc.; trisaccharides such as raffinose etc.; and other carbohydrates, such as starches (hydroxyethyl starch), cyclodextrin and maltodextrin. Amino acids are also suitable as supplements, with glycine being recommended. Mixtures of carbohydrates and amino acids are also considered to be within the scope of this invention. Inclusion of inorganic (eg, sodium chloride, calcium chloride, etc.), organic salts (eg, sodium citrate, sodium ascorbate, magnesium gluconate, sodium gluconate, tromethamine hydrochloride, etc.) and buffers are also contemplated. The inclusion of salts and organic solids such as ammonium carbonate, ammonium acetate, ammonium chloride or camphor has also been considered.

Another recommended embodiment includes perforated microstructures, which may contain, or may be coated with, filled species, which extend the residence time at the point of contact or support penetration through the mucosa. For example, anionic fillers are known to support mucosal adhesion, while cationic fillers can be used to attach microparticles formed with negatively charged bioactive agents, such as genetic material. Fillers can be introduced through binding or incorporation of polyanionic or polycationic materials, such as polyacrylic acid, polysilin, polylactic acid and chitosan.

In conjunction with, or instead of, the compounds discussed above, the perforated microstructures will preferably contain at least one active or bioactive agent. As used herein, the term "active agent" simply refers to the substance that enables the perforated microstructures to perform their desired functions. Furthermore, the name "active agent" is considered an integral part of the name "bioactive agent", unless otherwise prescribed by certain restrictions. In terms of the term "bioactive agent" it shall be understood to include any substance used in connection with the diagnosis or treatment of a patient's disease, condition or physical abnormality. Particularly recommended bioactive agents according to the present invention include anti-allergens, peptides and proteins, pulmonary surfactants, bronchodilators and anti-inflammatory steroids for use in the treatment of respiratory disorders, such as asthma, by inhalation therapy. Recommended active agents for use in accordance with the present invention include pigments, dyes, inks, stains, detergents, sweeteners, spices, adsorbents, absorption agents, catalysts, nuclear agents, thickeners, polymers, resins, insulators, fillers, fertilizers, phytohormones, insect pheromones, insect repellants, pet repellants, antifouling agents, pesticides, fungicides, disinfectants, fragrances, deodorants, and combinations thereof.

It will be clear that the perforated microstructures according to the present invention can contain only one or more active or bioactive agents (ie 100% by weight). However, in selected embodiments, the perforated microstructures may contain much less bioactive agents, depending on their activity. Therefore, in highly active materials, perforated microstructures can contain as little as 0.001 wt.%, although concentrations are greater than about 0.1 wt.%. recommended. Other embodiments of the present invention may contain more than 5%, 10%, 15%, 20%, 25%, 30%, or even 40% by weight. active or bioactive agents. More preferably, the perforated microstructures may contain more than about 50%, 60%,

70%, 75%, 80% or even 90% by weight. active or bioactive means. The exact amount of active or bioactive agent introduced into the perforated microstructures according to the present invention will depend on the selected agent, the required dose, and the actual form of the agent. It will be clear to those skilled in the art that such a determination can be made using well-known pharmacological procedures in combination with the data from the application of this invention.

In terms of pharmaceutical preparations, any bioactive agent can be formulated within the disclosed perforated microstructures, and is clearly within the scope of this invention. In particularly recommended embodiments, the selected bioactive agent can be administered in the form of an aerosolized drug. Therefore, particularly compatible bioactive agents consist of any drug which can be formulated as a flowable dry powder and which is relatively insoluble in the selected dispersion media. In addition, it is recommended that the formulated agent be subject to pulmonary or nasal administration in physiologically effective amounts. Compatible bioactive agents include hydrophilic and lipophilic respiratory agents, pulmonary surfactants, bronchodilators, antibiotics, antiviral agents, anti-inflammatory agents, steroids, antihistamines, leukotrienes, inhibitors or antagonists, anticholinergics, antineoplastics, anesthetics, enzymes, cardiovascular agents, genetic materials. including DNA and RNA, viral vectors, immunoactive agents, contrast agents, vaccines, immunosuppressive agents, peptides, proteins and their combinations. Particularly recommended bioactive agents for inhalation therapy include mammary cell inhibitors (anti-allergic), bronchodilators, and anti-inflammatory steroids such as, for example, cromoglycate (eg, sodium salt) and albuterol (eg, sulfate salt).

More specifically, examples of drugs or bioactive agents may be selected from, e.g., analgesics, e.g. codeine, dihydromorphine, ergotamine, fentanyl, or morphine; angina preparations, e.g. diltiazem; mammary gland inhibitors, e.g. cromolyn sodium; anti-infectives, eg, cephalosporins, macrolides, quinolines, penicillins, streptomycins, sulfonamides, tetracyclines, and pentamidines; antihistamines, e.g. methapyrilan; anti-inflammatory agents, e.g. fluticasone propionate, beclomethasone dipropionate, flunisolide, budesonide, tripedane, cortisone, prednisone, prednisolone, dexamethasone, heteromethasone, or triamcinolone acetonide; antitussives, eg, noscapine; bronchodilators, e.g. ephedrine, adrenaline, fenoterol, formatorol, isoprenaline, metaproterenol, salbutamol, sibuteroal, salmeterol, terbutaline; diuretics, eg, amiloride; anti-cholinergics, e.g. ipatropium, atropine, or oxitropium; pulmonary surfactants, eg Surfaxin, Exosurf, Survent; xanthines, eg, aminophylline, theophylline, caffeine; therapeutic proteins and peptides, eg, DNAse, insulin, glucagon, LHRH, naforalin, goserelin, leuprolide, interferon. ru IL-1 receptor, macrophage activation factor, such as lymphocytes and muramyl dipeptide, opioid peptides and neuropeptides, such as emkaphalin, endofin; kidney inhibitors, cholecystokines, DNAse, growth hormones, leukotriene inhibitors, etc. In addition, bioactive agents containing RNA or DNA sequences, particularly those useful for gene therapy, genetic vaccination, genetic tolerization, or countermeasures, may be incorporated into the disclosed dispersions as described herein. Representative DNA plasmids include, but are not limited to, pCMVB (available from Genzyme Corp., Framingham, MA, USA) and pCMV-B-gel (the CMV promoter linked to the E. coli Lac-Z gene, which encodes enzyme B -galactosidase). In any case, the selected active or bioactive agents can be bound, or incorporated into the perforated microstructures in any form, which provides the desired efficiency and which is compatible with the selected production technique. As used herein, the terms "bound to" or "associated" mean that the structural matrix or perforated microstructures may encapsulate, carry within, adsorb, absorb, be coated with, or shaped by the active or bioactive agent. Where appropriate, the active agents can be used in salt form (eg, alkali metal salts or amino salts, or as acid addition esters) or as esters or as solvates (hydrates). In this respect, the form of the active or bioactive agent can be chosen so as to optimize the activity and/or stability of the active agent and/or minimize the solubility of the agent in the suspension medium and/or minimize particle agglomeration.

It will further be clear that the perforated microstructures according to the invention can, if desired, contain a combination of two or more active ingredients. The means can be obtained in combination in one type of perforated microstructures or individually in separate types of perforated microstructures. For example, two or more active or bioactive agents can be contained in one starting material and can be spray-dried to obtain one type of microstructure, which contains a number of active agents. In contrast, individual active agents need to be added to different species and dried separately to obtain more types of microstructures with different compounds. These individual species in a suspension medium or in a dry powder ejection tank in any desired ratio are placed in an aerosol delivery system, as will be described below. Further, as indicated above, the perforated microstructures (with or without an associated agent) can be combined with one or more conventional agents (eg, a micronized drug) to create the desired dispersion stability or dispersibility of the powder.

Based on the foregoing, it will be clear to those skilled in the art that a wide variety of active or bioactive agents can be incorporated into the disclosed perforated microstructures. Therefore, the list of recommended active funds above is a list of examples only and is not given as a limitation. It will also be clear to those skilled in the art that the proper amount of bioactive agent and duration of dosing can be determined for formulations in accordance with already existing formulations and without unnecessary experimentation.

As can be seen from the above, various components can be attached to, or incorporated into, the perforated microstructures of the present invention. Similarly, multiple techniques can be used to create particles of desired morphology (eg, perforated or hollow/perforated configuration), dispersibility, and density. Among other methods, perforated microstructures compatible with the present invention can be formed by techniques including spray drying, vacuum drying, solvent extraction, emulsification or lyophilization, and combinations thereof. It will further be clear that the basic concepts of many of these techniques are known in the prior art, and would not, from the point of view of those procedures, require unnecessary experimentation to adapt them to obtain the desired perforated microstructure.

While several processes are compatible with this invention, particularly preferred embodiments typically consist of perforated microstructures formed by spray drying. As is well known, this method of drying is a one-step process, which converts the liquid starting material into a dried form of particles. In terms of pharmaceutical applications, it will be appreciated that spray drying has been used to create powder materials for various routes of administration during inhalation. See, eg, M. Sacchetti, van Oort, in: Inhalation Aerosols: Physical and Biological Basis for Therapy, A. J. Hickey, ed. Marcel Cekkar, New York, 1996, which is incorporated herein by reference.

In general, spray drying consists of bringing a highly dispersed liquid and a stream of hot air of sufficient volume into contact to evaporate and dry the liquid droplets. The preparation to be dried in this manner supplied (or starting material) can be any solution, suspension, mud, colloidal suspension or paste, which can be comminuted using the selected spray drying apparatus. In recommended embodiments, the starting material will consist of a colloidal system, such as an emulsion, reverse emulsion, microemulsion, multiple emulsion, dispersion of particles, or mud. Typically, the starting material is blown into a stream of hot filtered air, which evaporates the solvent and carries the dried product into a collector (vessel). The used air is then sucked off together with the solvent. It will be clear to those skilled in the art that several different types of apparatus can be used to obtain the desired product. For example, commercial spray dryers manufactured by Buchi Ltd. or Nitro Corp., will efficiently produce particles of the desired size.

It will further be clear that these spray dryers, and especially their atomizers (shredders), can be modified or adapted to special applications, i.e. simultaneous spraying of two solutions using a double nozzle. More specifically, a water-in-oil emulsion can be atomized from a single nozzle, and a solution containing an anti-sticking agent, such as mannitol, can be sprayed from a long nozzle. In other cases, it may be desirable to force the starting material solution through a specially designed nozzle, using a high pressure liquid chromatography (HPLC) pump. Provided that micro-structures with the correct morphology and/or composition are produced, the choice of apparatus is not critical and this will be clear to one skilled in the art with the views presented here.

While the resulting powder particles are typically approximately spherical in shape, nearly uniform in size, and often hollow, there may be some degree of irregularity in shape, depending on the drug incorporated and spray drying conditions. In many cases, the dispersion stability and dispersibility of perforated microstructures appears to be improved if there is an expanding propellant gas in their production. Particularly preferred embodiments may contain an emulsion with a spreading agent in the dispersion phase or in the continuous phase. The spreading agent is preferably dispersed with the surfactant solution using, for example, a commercially available microdisperser at a pressure of 5000 to 15000 psi (about 350 to about 1050 bar). This procedure creates an emulsion, preferably stabilized by added surfactant, with a typical content of droplets smaller than a micron, made of a propellant that is immiscible with water, dispersed in an aqueous continuous phase. The creation of such emulsions using this and other techniques are common and known to those skilled in the art. The propellant is preferably some fluorinated compound (eg, perfluoronexene, perfluorooxyl bromide, perfluorodecalin, perfluorobutyl ethane), which evaporates during the spray drying process, leaving behind in most cases hollow, aerodynamically light microspheres. As will be discussed in more detail below, other suitable liquid propellants include non-fluorinated oils, chloroform, freons, ethyl acetate, alcohols and hydrocarbons. Nitrogen and carbon dioxide are also considered as suitable propellants.

In addition to the previously mentioned compounds, inorganic and organic substances, which can be removed under reduced pressure by sublimation as part of the step after the basic production, are also compatible with the present invention. These sublimating compounds can be dissolved or dispersed as microcrystals in the spray drying propellant and include ammonium carbonate and camphor. Other compounds compatible with the present invention include solid stiffening structures that can be dispersed in the propellant or prepared in situ. These structures are then extracted after the creation of the initial particles using an extraction step after the base production. For example, latex particles can be dispersed and then dried with other wall-building compounds and then extracted with a suitable solvent.

Although the perforated microstructures are usually formed using a propellant, as described above, it will be understood that, in certain cases, an additional propellant and an aqueous dispersion of the drug and/or additives and surfactants, which are dried directly by the spray process, are required. In such cases, the formation process will have to be adapted to process conditions (eg, elevated temperatures), which could lead to the formation of hollow, relatively porous microparticles. Moreover, the drug can have special physicochemical properties (eg, crystallinity, elevated melting temperature, surface activity, etc.), which makes it particularly suitable for use in these techniques.

When a propellant is used, the degree of porosity and dispersion of the perforated microstructures appears to depend, at least in part, on the nature of the propellant, its concentration in the starting material (eg, in the form of an emulsion) and the spray drying conditions. In terms of porosity management, and, in the case of suspensions of dispersibility, it has surprisingly been found that the use of compounds, which until now have not been valued as propellants, can provide perforated microstructures with particularly desirable properties. More specifically, in this novel and unexpected aspect of the present invention, it has been found that the use of fluorinated compounds with a relatively high boiling point (ie, higher than about 40'C) can produce particles that are particularly porous. Such perforated microstructures are particularly suitable for inhalation therapy. In this regard, it is possible to use fluorinated or partially fluorinated propellants, with a boiling point higher than about 40, 50, 60, 70, 80, 90ͦC and even 95ͦC. Particularly recommended propellants have water boiling points, i.e. more than 100'C (eg, perflubron, perfluorodecathin). In addition to propellants with relatively low solubility in water (< 10-4 M), they are recommended, as they enable the production of stable emulsion dispersions with an average particle diameter of less than 0.3 μm.

As explained above, these propellants will preferably be incorporated into the emulsified starting ma ⁰ prior to spray drying. For the purposes of this invention, this starting material will preferably contain several active or bioactive agents, one or more surfactants or one or more additives. On the contrary, combinations of the previously mentioned components also fall within the scope of this invention. While the high boiling points (> 100⁰ C) of the fluorinated propellants are a desirable feature of the present invention, it will be appreciated that non-fluorinated propellants with similar boiling points (> 100⁰ C) can be used to create perforated microstructures. Examples of non-fluorinated ionic agents for use in the present invention include the formulas:

R1-X-R2 or R1-X

in which:

R1 or R2 are hydrogen, alkyl, alkenyl, aromatic, cyclic or combinations thereof, X is any group containing carbon, sulfur, nitrogen, halogen, phosphorus, oxygen and combinations thereof.

While not limiting the present invention in any way, it is believed that as the aqueous starting material evaporates during spray drying, it leaves a thin film on the surface of the particles. The resulting crust or wall of particles, created during the initial moments of drying appears to trap any high-boiling propellant in the form of hundreds of emulsion droplets (about 200-300 nm). As the drying process continues, the pressure inside the particles increases, vaporizing at least part of the trapped propellant and pushing it through the relatively thin shell. This penetration or blowing of gases seems to lead to the formation of pores or other defects in the microstructures. At the same time, other components of the particles (probably due to the propellant) rise from the interior to the surface, as the particles harden. This climbing seems to slow down as the drying process progresses as a result of increased resistance to mass movement caused by increased internal viscosity. When this movement stops, the particles solidify, with pores, cavities, faults, apertures, spaces, interstices, perforations or holes in them. The number of pores or defects, their size, and the resulting wall thickness are highly dependent on the formulation and/or nature of the selected propellant (eg, boiling point), its concentration, total solids concentration, and spray drying conditions. It will be very clear that this type of particle morphology contributes in part to increased particle dispersibility, suspension stability and aerodynamics.

It has surprisingly been found that significant amounts of these relatively high boiling point cores can remain in the resulting spray dried product. This means that the spray-dried perforated microstructures described here can contain up to 1%, 3%, 5%, 20%, 30% and even up to 40% by weight of enamel. propellant. In such cases, higher production yields are obtained as a result of increased particle density due to residual propellant. It will be clear to those skilled in the art that other fluorinated propellants can alter the surface characteristics of the perforated microstructures, thereby minimizing particle agglomeration during processing and further increasing dispersion stability. For other fluorinated propellants in particles, it can also reduce cohesive forces between particles, by creating obstacles or dampening attractive forces created during production (eg electrostatic). This reduction in cohesive forces may be particularly advantageous when using the disclosed microstructures with dry powder inhalers.

Further, the amount of residual propellant can be reduced by production conditions (such as outlet temperature), propellant concentration, or its boiling point. If the exit temperature is at or above the boiling point, the propellant escapes from the particles and the production yield decreases. Usable outlet temperatures are 20, 30, 40, 50, 60, 70, 80, 90, and even 100⁰C below the boiling point of the propellant. Even more recommended, the temperature difference between the outlet and the boiling point will range from 50 to 150⁰C. It will be clear to those skilled in the art that particle porosity, production yield, electrostatics and

dispersibility can be optimized first by identifying the process conditions (eg, outlet temperature) that are suitable for the selected active agent and/or additives. The preferred propellant can then be selected using the highest outlet temperature, where the temperature difference is at least 20 and up to 150⁰C. In some cases, the temperature difference may be outside this range, for example, when particles are produced in supercritical conditions or with the use of lyophilization techniques. It will further be appreciated by those skilled in the art that a suitable propellant concentration can be determined experimentally without undue experimentation, using techniques similar to those in the Examples provided herein.

While residual propellant may be preferred in selected embodiments, it may be desirable to remove substantially all propellant from the spray-dried product. In this respect, the residual propellant can be easily removed by the evaporation step after the basic production in the vacuum furnace. What's more, this technique after basic production can be used to create perforations on particles. For example, pores can be formed by spray drying the bioactive agent and an additive, which can be removed from the formed particles in a vacuum.

In any case, typical concentrations of the propellant in the starting material lie between 2% and 50% by weight. and more recommended between about 10% and 45% by weight. In other embodiments, concentrations of propellant will preferably be greater than about 5%, 10%, 15%, 20%, 25% or even 30% by weight. Some other starting material emulsions may contain 35%, 40%, 45% or even up to 50% wt. of the selected high-boiling compound.

In preferred embodiments, another method for identifying the concentration of the starting material propellant is to determine it as the ratio of the concentrations of the propellant and stabilizing surfactant (eg, phosphatidylcholine or PC) in the starting material precursor or emulsion. For fluorocarbon propellants (eg, perfluorooctyl bromide) and for explanatory purposes, the ratio is called the PFC/PC ratio. More broadly, it will be understood that compatible propellants and/or surfactants may be substituted by those exemplified without departing from the scope of the present invention, in any case, a typical PFC/PC ratio will range from about 1 to about 60 and more preferably from about 10 to about 50. In two-handed embodiments, the ratio will usually be greater than about 5, 10, 20, 25, 30, 40 or even 50. In this respect, FIG. 1 shows a series of images taken of perforated microstructures fabricated from phosphatylcholine (PC), using varying amounts of perfluorooctyl bromide (PFC), a fluorocarbon with a relatively high boiling point, as a propellant. PFC/PC ratios are given below each set of images, ie. fig. 1A to 1F. The formation and painting conditions are discussed in more detail in Examples I and II below. In terms of photographs, the column on the left shows intact microstructures, while the column on the right shows cross-sections of broken microstructures from the same preparations.

As can be clearly seen on si. 1. the use of PFC/PC ratios greater than 4.8 has tended to provide structures that are particularly compatible with the dry powder formulations and dispersions disclosed herein. Similarly, you are. 3, a micrograph that will be discussed in more detail in Example XII below, shows a re-armable porous morphology, obtained by using a higher boiling point propellant (in this case perfluorodecalin).

While relatively high boiling point propellants are one preferred aspect of the present invention, it will be appreciated that more common and less common propellants may be used to create compatible perforated microstructures. The propellant contains any volatile substance that can be incorporated into the plasma material for the purpose of producing a perforated foam structure of the obtained perforated microspheres. The propellant can be removed during the initial blowing process or during a step after basic production, such as vacuum drying or solvent evaporation. Suitable means include:

1. Dissolved agents with a low boiling point (below 100⁰C), which are miscible with aqueous solutions, such as methylene chloride, acetone, ethyl acetate and alcohols to saturate the solution.

2. Gas, such as CO2 or N2, or liquid such as freons, CFCs, HFAs, HFCs, HFBs, fluorocarbons, hydrocarbons, used at elevated pressure.

3. Liquid emulsions, immiscible with water, low boiling point (below 100°C), suitable for

use according to the present invention, which are the general formulas:

R1-X-R2 or R1-X

in which: R1 or R2 are hydrogen, alkyl, alkenyl, alkynyl, aromatic, cyclic or combinations thereof, X is any group containing carbon, sulfur, nitrogen, halogen, phosphorus, oxygen and combinations thereof. These fluids include CFCs, CFCs, HFAs, PFCs, HFCs, HFBs, fluoroalkanes, and hydrocarbons.

4. Dissolved or dispersed salts or organic substances, which can be removed under reduced pressure by sublimation in one step after basic production, such as ammonium salts, camphor, etc.

5. Dispersed solids, which can be extracted after initial particle formation, using a single extraction step after primary production, such as latex particles, etc.

With respect to these lower boiling propellants, they are typically added to the starting material in amounts of about 1% to 40% by weight. It was found that about 15% wt. propellant forms a spray-dried powder, which can be used to form stabilized dispersions according to the present invention

Regardless of which propellant is ultimately chosen, it has been found that compatible perforated microstructures can be produced particularly efficiently using a Buchi mini-dryer (model B-191, Switzerland). As will be apparent to those skilled in the art, the inlet and outlet temperatures of the dryer are not critical, but should be at such a level as to yield particles of the desired size and result in a product possessing the desired drug activity. In this regard, the inlet and outlet temperature is adjusted depending on the characteristics

melting of the components of the formulations and the composition of the starting material. Thus, the inlet temperature can be between 60 and 170" C, while the outlet temperature will be around 40 to 120⁰C, depending on the formulation of the starting material and the desired characteristics of the particles. Ideally, these temperatures will be from 90 to 120⁰C for the inlet and from 60 to 80⁰C, for outlet. The flow rate used in a spray dryer will typically be from about 3 to about 15 ml per minute. The air flow through the atomizer will vary from about 25 to about 50 l/minute. Commercially available spray dryers are well known to those skilled in the art, and suitable settings for various particle formations can be readily determined by standard empirical tests, with appropriate reference to the examples below.Of course, conditions can be adjusted to preserve biological activity for larger molecules such as proteins or peptides.

Although perforated microstructures are usually formed using fluorinated emulsion propellants, it will be clear that non-fluorinated oils can be used to increase the loading capacity of active or bioactive agents, without disrupting the microstructures. In this case, the choice of non-fluorinated oils is based on the solubility of the active or bioactive agent, water solubility, boiling point, and evaporation point. The active or bioactive agent will be dissolved in oil and then emulsified into the starting material. The preferred oil will contain significant stabilizing ability in relation to the selected medium, low solubility in water (> 103 M), boiling point higher than water and evaporation point higher than the outlet temperature of the propellant. In addition to surfactants, co-solvents in non-fluorinated oil, with the aim of increasing solubility, are also within the scope of this invention.

In particularly recommended versions, non-fluorinated oils can be used to dissolve agents or bio-active agents, which have limited solubility in aqueous preparations. The use of non-fluorinated oils is particularly suitable for increasing the loading capacity of steroids, such as beclamethasone dipropionate and triamquinolone acetonide. It is recommended that the oil or oil mixture for dissolving these clathrate-forming steroids will have a refractive index between 1.36 and 1.41 (eg, ethyl butyrate, butyl carbonate, dibutyl ether). In addition, process conditions such as temperature and pressure can be adjusted to increase the solubility of the selected agent. It will be understood that the selection of an appropriate oil or oil mixture and process conditions to maximize the filling capacity of a vehicle are well known to those skilled in the art, and in view of the instructions provided herein, can be performed without unnecessary experimentation.

Particularly preferred embodiments of the present invention include spray-dried preparations containing a surfactant, such as a phospholipid, and at least one active or bioactive agent. In other water-based preparations of this type, an additive with a hydrophilic medium such as, for example, a carbohydrate (i.e. glucose, lactose, or starch) can be added in addition to any standard surfactant. In this regard, various starches and derived starches suitable for use in the present invention are contemplated. Other components may optionally include conventional viscosity modifiers, buffers, such as phosphate buffers or other conventional biocompatible buffers or pH adjusting agents, such as acids or bases, and flavoring agents (to create isotonicity, hyperosmosis, or hyposmalarity). Examples of suitable salts include sodium phosphate (monobasic or dibasic), sodium chloride, calcium phosphate, calcium chloride, and other physiologically acceptable salts. Whichever components are chosen, the first step in particle production typically consists of preparing the starting material, preferably dissolving the selected drug in water to form a concentrated solution. The drug can also be dispersed directly into an emulsion, especially in the case of miscible agents. in the home. Alternatively, the drug can be injected in the form of a dispersion of solid particles. The concentration of the active or bioactive agent will depend on the required amount of agents, in the final powder, and the capabilities of the delivery device (eg, fine particle doses for MDI or DPI). If necessary, surfactants such as Poloxamer 188 or Span 80 can be dispersed in this additive solution.In addition, additives such as sugars and starches can also be added.

In selected versions, oil-in-water emulsions are then formed in a special vessel. The oil used will preferably be a fluorocarbon (eg, perfluorooctyl bromide, perfluorodecalin), which is emulsified using a surfactant, such as a saturated long-chain phospholipid. For example, one gram of phospholipid can be homogenized in 150 g of hot distilled water (eg, at 80⁰C), using a suitable mechanical high-shear mixer (eg, Ultra Turrax model T-25 mixer) at 8000 o /min for 2 to 5 minutes Typically, 5 to 25 g of fluorocarbon is added drop by drop to the dispersed surfactant solution during mixing. The resulting emulsion of perfluorocarbon in water is then processed using a high-pressure homogenizer to reduce the particle size. Typically the emulsion is processed at 12000 to 18000 psi (about 850 to about 1250 bar) in 5 separate passes at 50 to 80⁰C.

The active or bioactive agent solution and the perfluorocarbon emulsion are then mixed and fed into a spray dryer. Typically, these two preparations will be mixed, since the emulsion will preferably contain one aqueous continuous phase. While the bioactive agent is solubilized separately for verification purposes, it will be understood that in other embodiments, the active or bioactive agent may be solubilized (or dispersed) directly into the emulsion. In such cases, the active or bioactive emulsion is simply dried by spraying, without combining it with a separate drug preparation.

In any case, operating conditions such as inlet and outlet temperature, flow rate, atomization pressure, drying air flow and nozzle configuration can be adjusted according to the manufacturer's instructions, with the aim of producing the desired particle size and production yield of the resulting dry microstructure. The adjustment measures are as follows: inlet temperature between 80 and 170⁰C, outlet air temperature between 40 and 120⁰C; flow rate between 3 ml and 15 ml per minute; and suction air flow of 300 l/min, as well as air flow through the atomizer between 25 and 50 l/min. The selection of appropriate apparatus and processing conditions are well known to those skilled in the art, from the point of view of the instructions given here, and can be carried out without unnecessary experiments. In any case, the use of these and essentially equivalent procedures allow the creation of hollow porous aerodynamically light microspheres, particle diameters suitable for aerosol deposition in the lungs, microstructures that are both hollow and porous, with a honeycomb or foam-like shape. In particularly recommended designs, perforated microstructures consist of hollow, porous microspheres.

In addition to spray drying, perforated microstructures useful within the scope of this invention can be obtained by lyophilization. It will be clear to those skilled in the art that lyophilization is a process of drying in a frozen state, where water is sublimated from the preparation after it is frozen. A special advantage of the lyophilization process is that biological and pharmaceutical ingredients, relatively unstable in aqueous solution, can be dried without elevated temperatures (thereby eliminating the undesirable thermal effect) and then stored in a dry state, when there is a bit of a stability problem. -With regard to the present invention, such techniques are particularly compatible with the incorporation of peptides, proteins, genetic materials and other natural and synthetic macromolecules into particles or perforated microstructures, without impairing their physiological activity. Columns for creating lyophilized particles are known to those skilled in the art and will not require unnecessary experiments to create microstructures compatible with dispersions in accordance with the instructions given here. The dried cake with a fine foam structure content can be micronized using techniques known in the art, with the aim of obtaining particles with a size of 3 to 10 microns. Therefore, to the extent that lyophilization columns can be used to create microstructures of desired porosity and size, they are in accordance with the instructions provided herein and are specifically contemplated within the scope of this invention.

In addition to the above techniques, perforated microstructures or particles can be formed according to the present invention using a process in which the starting material (whether an emulsion or an aqueous solution) is rapidly introduced into a reservoir of heated oil (eg perflubron or not) with a mixture of forming agents. etc. FC high boiling points) under reduced pressure. Water and volatile solvents of the starting material easily boil and evaporate. This process gives a perforated structure from the means that shape the walls, the accidental coking of rice or corn. It is recommended that the means for creating walls are insoluble in heated oil. The resulting particles can be separated from the heated oil by filtration and then dried in a vacuum.

In addition, the perforated microstructures of the present invention can be formed using a two-emulsion process. In this procedure, the drug is first dispersed in a polymer dissolved in an organic solvent (eg methylene chloride) by sonication or homogenization. The primary emulsion is then stabilized by creating a multiple emulsion in a continuous aqueous phase containing one emulsifier such as polyvinyl alcohol. By evaporation or extraction, using usual techniques and apparatus, the organic solvent is then excluded. The resulting microspheres are then washed, filtered and dried prior to their combination with an appropriate suspension medium in accordance with the present invention.

Whichever production process is ultimately chosen for the production of perforated microstructures, the resulting powders possess a whole range of advantages, which make them particularly compatible for use with inhalation therapy devices. In particular, the physical properties of perforated microstructures make them extremely effective when used in dry powder inhalers and in the creation of stabilized dispersions, which can be used in connection with metered dose inhalers, nebulizers and liquid dose devices. As such, perforated microstructures enable efficient pulmonary delivery of bioactive agents.

In order to maximize dispersibility, dispersion stability and optimize distribution after administration, the mean geometrical particle size is recommended to be around 0.5 - 50 microns, even more recommended 1 - 30 microns. It will be clear that large particles (ie, larger than 50 microns) are not recommended in applications where a valve or a small opening is used, because large particles tend to aggregate or separate from the suspension, which in principle can lead to clogging of the device. In particularly preferred embodiments, the average diameter (or diameter) is often less than 20 or even less than 10 microns. More preferably, the geometric mean diameter is less than about 7 or 5 microns, and more preferably less than 2.5 microns. Other recommended embodiments will contain preparations where the mean geometric diameter of the perforated microstructures is between 1 and 5 microns. In particularly preferred embodiments of the perforated microstructures, a powder of dry, hollow, porous microspherical shells approximately 1 to 10, or 1 to 5 microns in diameter, with a shell thickness of about 0.1 to about 0.5 microns will be obtained. A particular advantage of this invention is that the concentration of dispersion particles and the composition of the structural matrix can be adjusted to optimize the properties of the selected particle size.

As indicated in previous statements, the porosity of microstructures can play a significant role in providing dispersibility (eg, in DPI) or dispersion (eg, for MDIs or foggers). In this regard, the mean porosity of perforated microstructures can be determined by electron microscopy, related to modern imaging techniques. More specifically, electron micrographs of representative examples of perforated microstructures can be obtained and analyzed digitally with the aim of quantifying the diversity of examples of perforated microstructures in preparations. Such procedures are well known in the art and can be used without undue experimentation.

In order to use within this framework, the mean porosity (ie the percentage of the surface of the particles, open to the interior and/or the central cavity) of the recommended perforated mirostructures, can range from about 0.5% to about 80%. In still more preferred embodiments, the mean porosity will be greater than about 2%, 5%, 10%, 20%, 25% or 30% of the surface area of the microstructures. In other embodiments, the mean porosity of the microstructures can be greater than about 40%, 50%, 60%, 70%, and even 80%. As for the pores themselves, they typically range in size from about 5 nm to about 400 nm, medium pore sizes are recommended from about 20 to about 200 nm. In particularly preferred embodiments, the mean pore size is in the range of 50 to about 100 nm. As can be seen in fig. 1A1 to 1F2 and from the more detailed discussion below, an important advantage is that, according to the present invention, pore size and porosity can be precisely controlled by careful selection of the components used and manufacturing parameters.

In this regard, the particle morphology and/or the hollow structure of the perforated microparticles also play an important role in the dispersibility or cohesiveness of the dry powder formulations disclosed herein. That is, it was surprisingly discovered that the inherent cohesive character can be overcome by lowering the van der Waals attractive and liquid bridging forces, which typically exist between dry particles. More specifically, in accordance with the instructions provided herein, improved powder dispersibility can be obtained by engineering particle morphology and density, as well as by managing humidity and loading. In this regard, the perforated microstructures according to the present invention contain pores, cavities, openings, defects and other internal spaces, which reduce the surface contact area between the particles, thus minimizing the forces between the particles. In addition, the use of surfactants such as phospholipids and fluorinated propellants in accordance with the provisions herein can contribute to the flow properties of powders by reducing the load and strength of electrostatic forces, as well as moisture content.

Increasing numbers of fine powders, (eg < 5 pm) have poor dispersibility, which can become a problem when trying to administer, aerosolize and/or package the powders. In this regard, the main forces governing particle interactions can typically be divided into long-range and short-range forces. Long-range forces include gravitational attractive forces and electrostatic forces, where the interaction varies as the square of the distance or diameter of the particles. Important short-range forces include van der Waals forces, hydrogen bonding forces, and liquid bridging forces. The last two short-range forces differ from the others in that they are felt when there is already contact between the particles. An important advantage of the present invention is that these attractive forces can be significantly reduced by using perforated microstructures as described herein.

In an effort to overcome these attractive forces, typical prior art DPI powders contain micronized drug particles, supported on large carrier particles (eg, 30 to 90 microns), such as lactose or agglomerated units of pure drug particles or agglomeration of fine lactose particles with the pure drug, since they fluidize more easily than pure drug particles. In addition, the mass of the drug required for inclusion is typically less than 100 pg and therefore, being so small, practically cannot be measured. Therefore, larger lactose particles, according to the prior art, work both as carrier particles for aerosolization and as a bulking agent for easier dosing. The use of large particles within these formulations is used because powder dispersibility and aerosolization improve with increasing particle size and, as a result, decrease intercellular forces (French, O. L., Edwards, D. A. and Niven, R. W., J. Aeroso! Sci., 27, 769-783, 1996), which is incorporated herein by reference. That is, previous formulations often use large particles or carriers to overcome forces that govern dispersibility, such as van der Waals forces, liquid bridging and electrostatic attractive forces, that exist between particles.

It will be clear to those skilled in the art that van der Waals (VDW) attractive forces appear with a short range and depend, at least in part, on the surface contact between interacting particles. When two dry particles approach a long one, the VDW forces increase with increasing contact area. For two dry particles, the magnitude of VDW interaction force F0vdw can be calculated by the following equation:

where h is Planck's constant, is the angular frequency, d0 is the distance at which the adhesion force is greatest, and r1 and r2 are the radii of the two interacting particles. Therefore, it will be clear that one way to minimize the magnitude and strength of VDW forces in dry powders is to reduce the intercellular areas in the do dir. It is important to note that the size is up to the mark of the surface in contact. The smallest amount of contact between two bodies will occur if these bodies are perfect spheres. In addition, the area of contact will decrease even more if the particles are very porous. Therefore, the perforated microstructures according to the present invention act by reducing particle interactions and corresponding iVDW forces. It is important to note that the reduction in VDW forces is largely the result of the unique morphology of the powder particles according to this invention, rather than an increase in the geometric diameters of the particles. In this regard, it will be clear that particularly preferred embodiments of the present invention provide powders with medium or small particle sizes (eg, geometric mean diameter < 10 microns), which provide relatively low VDW attractive forces. In contrast, solid, non-spherical particles, like conventional micronized drugs of the same size, will give higher intercellular forces and therefore have a low dispersing ability.

Further, as indicated above, electrostatic forces that attack powders occur when one or both particles are electrically charged. This phenomenon will result in either an attractive or repulsive force between the particles, depending on the sign of the charge. In the simplest case, electric charges can be described with the help of Coulomb's new law. One way to minimize or adjust the electrostatic forces between particles is if one or both particles have non-conductive surfaces. Thus, if powders with a perforated microstructure have additives, surfactants or active agents, which are relatively non-conductive, then any electrical charge created on the particle will be unevenly distributed over the surface of the particles. Thus, the half-life of a charge on a powder with non-conductive components will be relatively short, since the retention of elevated colors is dictated by the electrical resistivity of the material. Non-conductive, or electrically resistive, materials are materials that will behave as poor conductors or receivers of electrical charge.

Derjaguin et al., (Muller, V. M., Yuschenko, V. S., and Derjaguin, B. V., Colloid Interface Sci., 1980, 27, 11SUS), incorporated herein by reference, provide an ordered list of molecular groups in terms of their ability to receive or they eject an electron. In this respect, examples of g'up will be placed in the following order:

Donor: -NH2, > -OH > -COOR > -C5H9 > -halogen > -COOH > -CO > -CN Recipient

The present invention provides a reduction of electrostatic effects in applied powders by using relatively non-conductive materials. Using the above techniques, recommended non-conductive materials will contain halogenated and/or hydrogenated components. Materials such as phospholipids and fluorinated propellants can coagulate to some degree in spray-dried powders and are handy because they can create resistance to charge generation. It will be clear that the retention of certain propellants (eg, fluorocarbons) in the particles, even at relatively low amounts, can help minimize the electrical charging of the perforated microstructures, which is typically generated during spray deposition and cyclonic separation.

Based on general electrostatic principles and the guidance provided herein, those skilled in the art will be able to identify additional materials that will serve to reduce electrostatic forces in the published powders without the need for experimentation. Furthermore, if necessary, electrostatic forces can also be managed and minimized using electrical charge and charging techniques.

In addition to the surprising advantages described above, the present invention also provides a reduction or damping of hydrogen or liquid bonding. As known to those skilled in the art, both hydrogen bonding and liquid bridging can occur due to moisture absorbed into the powder. In the general case, higher humidity results in higher average particle forces for hydrophilic surfaces. This is a significant problem in the prior art with pharmaceutical preparations for inhalation therapies, which tend to use relatively hydrophilic compounds, such as lactose. Moreover, in accordance with the instructions given above, adhesion forces due to adsorbed water can be adjusted or reduced by increasing hydrophobicity or contact surfaces. It will be clear to those skilled in the art that increasing the hydrophobicity of the particles can be achieved by the choice of additives and/or the coating technique after the basic production step, such as the application of a fluidized bed. Thus, recommended additives include hydrophobic surfactants such as phospholipids, fatty acid soaps and cholesterol. In view of the instructions provided herein, it is understood that one skilled in the art can identify materials exhibiting similar desirable properties without unnecessary experimentation.

In accordance with the present invention, procedures such as altering the shear angle and index can be used to affect the flowability of dry powders. Shear angle is defined as the angle formed when a powder bath is poured onto a flat surface. Powders with a shear angle of 45 to 20* are more recommended and indicate a suitable fluidity of the powder. In more detail, powders having a shear angle between 33 and 20* exhibit relatively low shear forces and are particularly useful in pharmaceutical preparations for inhalation therapy (eg, with DFI). The shear index, although it takes more time to measure than the shear angle, is considered more reliable and easier to determine. Those skilled in the art will appreciate that the experiment described by Amidon and Houghton (G. E. Amidon, and M. E Houghton, Pharm. Manuf, 2, 20, 1985) incorporated herein by reference) can be used to determine the shear index. for use in the present invention. As described by S. Kocov and N. Pilpel, J. Pharmacol., 9, 33-65, 1973, also incorporated herein by reference, the shear index is estimated from powder parameters such as the tensile stress, the actual angle of internal friction, allowable tensile stress and specific cohesion. In the present invention, powders with a shear index of less than about 0.99 are preferred. Even more preferably, the powders disclosed within these preparations, methods and systems will have a shear index of less than about 1.1. In particularly preferred embodiments, the shear index will be less than 1.3, or even less than 1.5. Of course, powders of different index shears can be used, provided that the result is effective deposition of active or bioactive agents in the required place.

It will also be clear that it has been shown that the fluidity properties of the powders are in good correlation with the measured bulk density. In this regard, attitudes towards the prior art (C. F Harvwood,

J. Pharm. Sci., 60, 161-163, 1971) were that an increase in bulk density correlated with better flowability, as predicted by the shear index of the material. In contrast, it has surprisingly been found that with the perforated microstructures according to the present invention, better flow properties are exhibited by relatively low bulk density powders. This means, the hollow porous powders according to the present invention have better flow properties compared to powders with virtually no pores. To this end, it has been found that it is possible to obtain powders with a bulk density of less than 0.5 g/cm 3 which have particularly good flowability. It is even more surprising that it was found that it is possible to obtain perforated microstructures with a volume density of less than 0.3 g/cm3, or even less than 0.1 g/cm3, which possess excellent fluidity properties. The ability to produce powders with better flowability further emphasizes the novel and unexpected nature of this invention.

In addition, it will be clear that the reduced attractive forces (e.g., VDW, electrostatic, hydrogen and liquid bonding forces, etc.) and excellent fluidity, obtained with perforated microstructures, make them particularly suitable for inhalation therapies (e.g., with inhalation devices, such as DFI, MDI, foggers). In addition to better fluidity, porous and/or hollow microstructures also play a significant role in the achieved properties of the aerosol powder during blowing. This phenomenon applies to perforated microstructures, aerosolized in the form of suspensions, as in the case of MDI or nebulizers, or when giving perforated microstructures in a dry state, as in DFI. In this regard, perforated structures with a relatively large surface area of dispersed microparticles allow them to be carried in the stream of gases during inhalation, easier and over greater distances compared to non-perforated particles of the same size.

More closely, due to their high porosity, the density of the particles is significantly less than 1.0 g/cm3, typically less than 0.5 g/cm3, often below 0.1 g/cm3 and even below 0.01 g/cm3 . Contrary to the geometric size of the particles, the aerodynamic size caet, of perforated microstructures depends on the density of the particles, p: caer= dgeo A

where C. is the geo geometric diameter. For a particle density of 0.1 g/cm3 C. aei will be about three times smaller than C. geo leading to increased deposition of particles in the peripheral parts of the lungs and, therefore, less deposition in the throat. In this regard, the mean aerodynamic diameter of the perforated microstructures is preferably less than about 5 microns, more preferably less than 3 microns, and, in particularly preferred embodiments, less than 2 microns. These particle distributions will act to increase deep lung deposition of the bioactive agent, whether delivered by DFI, MDI, or nebulizer. Furthermore, a larger geometric diameter than the aerodynamic diameter brings particles closer to the walls of the alveoli, thus increasing the deposition of particles with a smaller aerodynamic diameter.

As will be shown below in the Examples, the particle size distribution of the aerosol formulations of the present invention is measurable by conventional techniques such as, e.g. by cascading impacts (impacts) or by means of analytical procedures for calculating the time of flight. In addition, determination of the delivered dose from the inhaler was performed according to the proposed American Pharmaceutical Method (Pharmaceut/ca, Previews, 22/1996, 306t), which is incorporated herein by reference. These and related procedures enable the calculation of the "fine aerosol fraction" in the aerosol itself, which corresponds to those particles that are likely to settle effectively in the lungs. As used herein, the term "aerosol fine fraction" refers to the percentage of the total amount of active flow, which is delivered upon activation of the device from the mouthpiece of a DPI, MDI, or nebulizer, to plates 2 - 7 of an 8-stage Anderson cascade impactor. Based on such measurements, formulations according to the present invention will preferably have a fine aerosol fraction of about 20% by weight. or more perforated microstructures, more preferably will have a fine aerosol fraction of about 25 to 80% by weight. and even more recommended from about 30 to 70% by weight. In selected embodiments of the present invention, there will preferably be a fine aerosol fraction of more than about 30%, 50%, 70% or 80% by weight.

Furthermore, it was also shown that the formulations according to the present invention have relatively low deposition rates in comparison with the preparations according to the prior state of the art, on the introduction part and on plates 0 and 1 of the impactor. The deposition of these components is related to the deposition in the human throat. More closely, most of the commercially available MDI and DFI simulated throat depositions of about 40 - 70% by weight. total doses, while the formulations of the present invention had typical deposition of less than about 20 wt.%. Accordingly, preferred embodiments of the present invention simulated throat deposition of less than about 40%, 35%, 30%, 25%, 20%, 15% or even less than 10% by weight. It will be clear to those skilled in the art that the significant reduction in throat deposition made possible by the present invention will result in a reduction in corresponding side effects such as throat irritation and candidiasis.

With respect to the convenient settling of the present invention, it is well known that MDI devices propel suspension particles from themselves at high velocity towards the back of the throat. Since the formulations according to the previous state of the art contain a large percentage of large particles and/or aggregates, even up to 2/3 or more of the ejected dose can enter the body.

What's more, the undesirable injection profile of common powder preparations is also shown in conditions of low speed of movement of particles, as happens with DPI devices. In general, this problem is inherent when solid, dense particles, which are subject to aggregation, are aerosolized. However, as discussed above, the new and unexpected properties of the stabilized dispersions of this invention lie in the low deposition in the throat after administration by inhalation devices such as DPIs, MDIs or nebulizers.

While not wishing to be bound by any particular theory, it appears that reduced throat deposition according to the present invention results from reduced particle aggregation and from the hollow and/or porous morphology of the embedded microstructures. This means that the hollow and porous nature of the dispersed microstructures slows down the speed of particle movement in the propellant stream, in the case of DPI, just as a hollow7porous ball slows down faster than a soccer ball. Thus, instead of hitting and sticking in the throat, relatively slow particles are inhaled from the patient's cheese. Moreover, the highly porous nature of the particles allows the propellant within them to quickly leave the particles and the density of the particles to drop before hitting the throat. Therefore, a significantly higher percentage of the bioactive agent is deposited in the pulmonary airways, where it can be efficiently absorbed.

With regard to inhalation therapies, it will be clear to those skilled in the art that powders made of perforated microstructures according to this invention are suitable above all for DPIs. Common DPI devices, or dry powder inhalers, contain powder formulations and devices in which predetermined doses of the drug, either alone or in admixture with lactose as carrier particles, are given in the form of a fine mist or aerosol of dry powder for inhalation. The drug is formulated in such a way that it is easily dispersed into separated particles between 0.5 and 20 microns in size. The powder is activated either by inhalation, or by some force from an external administration device, such as compressed air. DPI formulations are usually packed in individual doses or a tank is used with the possibility of determining multiple doses, by manually transferring them to the device.

DPIs are usually grouped according to the dosing system used. In this regard, the two basic types of DPI devices consist of single-dose devices and shared reservoirs. As used herein, the term "reservoir" is to be understood in a general sense, to include both configurations, unless otherwise required by the associated limitations. In any case, single dose delivery systems require powder dosage formulations to be arranged as a single unit. With such a system, formulations are pre-filled into dosage compartments, which can be packed in foil, or in strips, in order to prevent the ingress of moisture. Other single-dose packages include hard gelatin capsules. Most single dose reservoirs designed for DPI are filled using the fixed volume technique. As a result, there are physical limitations (density) to the final dose that can be measured into an individual package, dictated by the fluidity of the powder and its density. Now, the mass range of dry powder, which can be filled into the reservoir of individual doses, is in the range of 5 to 15 mg, which corresponds to a loading of 25 to 500 p. g per dose. In contrast, common reservoir systems provide the exact amount of powder, which is measured during individual administration, for up to about 200 doses. Again, as with single dose systems, the powder is dosed using a fixed volume cell or scoop, into which the powder is poured. Thus, the density of the powder is the main factor that limits the minimum dose that can be administered by the device. Now, DPI devices with shared reservoirs can dispense from about 200 pg to 20 mg of powder for a single use.

DPI devices are designed to be manufactured to either break the capsule/band or deliver the powder to a common reservoir during use and then disperse it from the mouthpiece or actuator due to patient inhalation. When the preparations according to the prior art are activated from the DPI device, the lactose/drug aggregates are aerosolized and the patient inhales the dry powder mist. During inhalation, the carrier particles create shear forces, which separate some of the particles of the micronized drug from the surface of the lactose particles. It will be clear that after that the micronized drug particles are taken to the lungs. Large lactose particles hit the throat and upper respiratory tract due to size limitations and inertial forces. The efficiency of delivery of drug particles is dictated by the degree of adhesion with the carrier particles and their aerodynamic properties.

Disaggregation can be increased by improving the formulation, process and design of the device. For example, fine particle lactose (FPL) is often mixed with a coarse lactose carrier, with FPL attacking the binding sites on the high energy carrier particles. This procedure also provides more passive sites for the adhesion of micro-arrayed drug particles. This tertiary mixture with the drug was shown to give statistically significant increases in the portion of the fine fraction. Other strategies include initial process conditions, where drug particles are mixed with FPL to obtain agglomerated units. In order to further increase particle deposition, many DFIs are designed to provide aggregation by passing the dose over obstacles, or through tortuous channels, which break these features.

Adding FPL to agglomerations with FPL and with the help of specialized devices, an increase in the disaggregation of the formulations is achieved, but however, the clinically significant parameter is the fraction of fine particles received by the patient. Although an improvement in disaggregation can be achieved, the main problem still exists with current DPI devices in that the increase in inhalation dose is accompanied by an increase in inhalation napiore. This is the result of an increase in the fraction of fine particles, which corresponds to an increased disaggregation of particle agglomerates, as the air flow increases through the inhaler with an increase in inhalation effort. Therefore, the accuracy of dosing is impaired, which leads to complications when the device is used to administer highly effective drugs to sensitive populations, such as children, adolescents, and the elderly. What's more, the inaccuracy of the dosage, combined with the usual preparations, could complicate obtaining a license for use.

With great contrast, the perforated microstructures according to this invention circumvent the difficulties encountered with preparations from the prior art. This means that improving DPI performance can be achieved by fine-tuning particles, their size, aerodynamics, morphology and density, as well as by managing validity and load. In this regard, the present invention provides formulations in which the drug and additives are preferably attached to, or form part of, perforated microstructures. As noted above, preferred embodiments of the present invention typically provide powders with a bulk density of less than 0.1 g/cm 3 and often less than 0.05 g/cm 2 . It will be clear that by obtaining powders of an order of magnitude less density than usual DPI formulations, they enable significantly smaller doses of the selected bioactive agent, which are filled into a single dose tank or measured in DPI devices with a tank. The ability to efficiently measure small amounts is of particular importance for small doses of steroids, long-acting bronchodilators, and new protein and peptide drugs proposed for administration with DPI devices. What's more, the ability to efficiently deliver particles without attached carrier particles simplifies product formulation, filling, and reduces unwanted side effects.

As discussed above, the hollow porous powders of the present invention exhibit superior properties, as measured by hold angle or shear index by the methods set forth above, when compared to equivalent powders with virtually no pores. This means better flowability of the powder, which seems to be a function of volume

density and morphology of the particles, were observed in powders with a density below 0.5 g/crrA. It is recommended that the powders have a density lower than 0.3 g/crrA or even lower than 0.3 and 0.1 g/cm^ and even below 0.05 g/cm^. In this regard, the theory was put forward that perforated microstructures with pores, cavities, openings, faults or long irregularities contribute to powder fluidity by reducing surface contact between particles and minimizing interparticle forces. In addition, the use of phospholipids in recommended designs and the retention of fluorinated propellants can also contribute to improving the flowability of powders by reducing the load and strength of electrostatic forces as well as moisture content.

In addition to the previously mentioned advantages, the published powders have favorable aerodynamic properties, especially suitable for use with DPI. More specifically, the perforated structure and relatively large surface area of micro-particles allows them to be carried by the stream of gases during inhalation more easily and further than relatively non-perforated particles of comparable size. Due to its high porosity and low density, the provision of perforated microstructures by DPI contributes to increased deposition of particles in the peripheral parts of the lungs and, accordingly, less deposition in the throat. This distribution of droplets contributes to an increase in the deposition of particles deep in the lungs of the administered drug, which is recommended from the point of view of systemic administration. What's more, with the constant improvement of DPI preparations, low density, highly porous powders according to this invention avoid the need for carrier particles. Since large carrier lactose particles will hit the throat and upper respiratory tract due to their size, elimination of such particles minimizes deposition and any associated "choking" that occurs with conventional DPI devices.

With their application in dry powder configurations, it will be clear that the perforated microstructures of the present invention can be incorporated into a suspension medium to obtain stabilized dispersions. Among other uses, stabilized dispersions provide efficient delivery of bioactive agents to the patient's pulmonary airways, using MDI, nebulizer, or liquid dose (LDI) techniques.

As with DPI delivery, administration of a bioactive agent by MDI, nebulizer, or LDI may be indicated for the treatment of mild, moderate, or severe, acute, or chronic symptoms or for prophylaxis. Moreover, the bioactive agent can be administered in the treatment of local or systemic conditions or diseases. It will be understood that the precise administration of doses will depend on the age and condition of the patient, the drug used and the frequency of administration, and will ultimately be the responsibility of the attending physician. When combinations of bioactive agents are used, the dose of each component of the combination will usually be determined as well as the dose of a single drug administered.

It will be clear to those skilled in the art that the improved stability of dispersions or suspensions is largely achieved by lowering the VDW attractive forces between the suspended particles, and by reducing the density difference of the suspension medium and the particles. In accordance with the instructions given here, increasing the stability of suspensions can be contributed by the production of perforated microstructures, which will then be dispersed in a compatible suspension medium. As discussed above, perforated microstructures contain pores, faults, and other internal voids, which allow the liquid suspension medium to penetrate or absorb through the particle interface. Particularly recommended versions of perforated microstructures are those that are both hollow and

porous, looks almost like honeycomb or foam. In particularly recommended designs, perforated microstructures contain hollow, porous microspheres, dried by spraying. When the perforated microstructures are placed in a suspension medium (ie, a propellant), that medium is able to penetrate the particles, thus creating a "homodispersion", whereby the continuous and dispersed phases cannot be distinguished. Since they are defined or " "virtual" particles (i.e., having a volume determined by the matrix of microparticles) built almost completely from the medium in which they are suspended, the forces that drive the particles towards aggregation are minimized. In addition, the differences of the densities of the defined particles and the continuous phase are minimized, since the microstructures are foamed in that medium, thereby effectively retarding particle thickening or settling. As such, the perforated microspheres and stabilized suspensions of the present invention are particularly compatible with many aerosolization techniques, such as MDI and fogging. Moreover, the stabilized dispersions can be used in liquid device applications doses.

Typical prior art suspensions (e.g., for MDI) consist mostly of solid particles and small amounts (< 1% by weight) of surfactant (e.g., lecithin, Span-85, oleic acid) to increase electrostatic repulsion between particles or polymers in order to statically reduce the interaction of particles. In sharp contrast to this, the suspensions of the present invention are designed not to increase the repulsion between particles, but rather to decrease their mutual attractive forces. The basic forces that support flocculation (formation of flakes) in non-aqueous environments are VDW attractive forces. As discussed above, VDW forces are of quantum mechanical origin and can be thought of as an attraction between oscillating dipoles (ie, dipole interaction due to dipole action). Dispersion forces are of extremely short range and magnitude, of the order of the sixth power of the distance between atoms.

When two microscopic bodies approach each other, the dispersion attraction between atoms adds up. The resulting force has a much larger range and depends on the geometry of the body in interaction.

In more detail, for two spherical particles, the size of the VDW potential, ^, can be approximately determined as:

in order to reduce the actual Hameker constant, the components of the structural matrix (which defines the perforated microstructure) are chosen, preferably, to obtain a Hameker constant relatively close to that of the selected suspension medium. In this regard, the actual values of the Ha maker constant of the suspension medium and particles can be used to determine the compatibility of the dispersion ingredients and provide a good forecast of the stability of the preparation. Alternatively, relatively compatible components of the perforated microstructures and suspension could be selected, using characteristic physical values, which agree with the measured value of Hamecker's constant, but can be more easily recognized.

In this regard, it has been found that the refractive index value of many compounds tends to be proportional to the corresponding Hamecker constant. Therefore, refractive index values, which are easily measured, can be used to provide fairly good guidance as to combinations of suspension media and particle additives to achieve dispersions that possess a relatively small actual Hamecker constant and associated stability. It will be appreciated that since the refractive indices of the compounds are readily available or easily determined, the use of these values for the formulation of stabilized dispersions in accordance with the present invention can be made without undue experimentation. By way of illustration only, the refractive indices of several compounds compatible with the published dispersions are given in Table I immediately below:

Table I:

In addition to the compatible dispersion components listed above, it will be clear to those skilled in the art that dispersion formations in which the components have a refractive index difference of less than 0.5 are recommended. This means, the index of refraction of the suspension medium will preferably be different by about 0.5 from the index of refraction of the perforated microstructure particles. It will further be clear that the refractive index of the suspended medium and particles can be measured directly, or approximated, using the refractive index of the principal component of each respective phase. For perforated microstructures, the major component can be determined on a weight percent basis. For the suspension medium, the main component will be obtained on the basis of volume percentage. In selected embodiments of the present invention, the refractive index difference will preferably be less than about 0.45, about 0.4, about 0.35, or even less than about 0.3. In view of the fact that lower refractive index differences provide greater stability of dispersions, particularly preferred embodiments possess refractive index differences of less than about 0.28, about 0.25, about 0.2 or even less than about 0.1. It is clear that one skilled in the art will be able to determine which additives are especially compatible, without unnecessary experimentation, bearing in mind this publication. The final choice of recommended supplements will also be influenced by other factors, including biocompatibility, state of manageability, ease of manufacture, and cost.

As discussed above, the minimization of density differences between the particles and the continuous phase largely depends on the hollow nature of the perforated microstructures, as well as the fact that the suspension medium contains the largest part of the particle volume. As used herein, "particle volume" corresponds to the volume of the emulsion medium that would be displaced by the embedded hollow/porous particles, if full, i.e. volume determined by particle boundaries. For explanatory reasons, and as discussed above, these fluid-filled particle volumes may be referred to as "virtual particles". less than 70% of the mean particle volume (or less than 70% of the virtual particle). More preferably, the microstructure matrix volume will be less than about 50%, 40%, 30% or even about 20% of the mean particle volume. And even more preferably , the mean shell/matrix volume will consist of less than about 10%, 5%, 3%, or 1% of the mean particle volume. Those skilled in the art will appreciate that such matrix or shell volumes typically contribute to the virtual particle density, which is primarily dictated by the suspension Of course, in the selected implementations, the additives used to create the perforated microstructure can be chosen so that the density of the resulting matrix or shell is close to the density of the surrounding suspension medium.

It will further be clear that the use of such microstructures will allow the apparent density of virtual particles to approach that of the suspension medium, essentially excluding the attractive VDW forces. Moreover, as discussed earlier, the components of the microparticle matrix are carefully chosen, as much as possible due to other circumstances, to approximate the density of the suspension medium. Therefore, in preferred embodiments of the present invention, the virtual particles and the suspension medium will have a density difference of less than about 0.6 g/cm 3 . This means that the mean density of virtual particles (defined by the matrix boundaries) is around 0.6 g/cm3 of the suspension medium. More preferably, the mean virtual particle density will be within 0.5, 0.4, 0.3 or 0.2 g/cm 3 of the selected suspension medium. In more recommended embodiments, the density difference will be less than about 0.1, 0.05, 0.01 or even less than 0.005 g/cm3.

In addition to the previously mentioned advantages, the use of hollow, porous particles enables the formation of free-flowing dispersions, containing much larger volumes of particles in suspension. It will be appreciated that prior art formulations at volumes approaching tight packing typically result in a dramatic increase in dispersion viscoelastic behavior. The rheological behavior of this type is not favorable for applications on MDI devices. It will be clear to those skilled in the art that the particle volume fraction can be defined as the ratio of the apparent volume of the particles, (ie the volume of the particles to the total volume of the system). Each system owns most of the volume or part of the package. For example, particles in simple volume packing reach a maximum packing fraction of 0.52, while those in centered volume/hexagonal close packing reach a maximum packing fraction of about 0.74. For non-spherical particles or polydisperse systems, the observed values sz different. Therefore, bulk packing is often limited as an empirical parameter for a given system.

Here, it was surprisingly found that the porous structures of this invention do not exhibit the undesirable viscoelastic behavior of a large part of the fractions, which approaches close packing. In contrast, they remain as free-flowing suspensions with little or no tensile stress, compared to analogous suspensions of solid particles. The low viscosity of the published suspensions is considered to be due, at least in large part, to relatively small attractive forces of VDW between liquid-filled, hollow, porous particles. As such, selected embodiments of fraction fractions of the disclosed dispersions are greater than about 0.3. Other embodiments may have packing values on the order of 0.3 to about 0.5 or on the order of 0.5 to about 0.8, with the larger values approach close packing conditions. Moreover, the creation of relatively concentrated dispersions can be further enhanced by the stability of the formulations.

Although the methods and compositions of this invention can be used to form relatively concentrated suspensions, the stabilizing agents work just as well at much smaller package volumes and such dispersions are contemplated as part of this invention. In this regard, it will be clear that dispersions containing small volume fractions are extremely difficult to stabilize using the prior art. In contrast, the dispersions of bioactive agent-containing perforated microstructures described herein are particularly stable even at low volume fractions. Accordingly, the present invention enables stabilized dispersions, and particularly respiratory dispersions, to be formed and used at volume fractions of less than about 0.3. In some preferred embodiments, the volume fraction is about 0.0001 - 0.3, more preferably 0 , 001 - 0.01. Another preferred embodiment comprises stabilized suspensions with volume fractions of about 0.01 to about 0.1.

Perforated microstructures according to this invention can also be used to stabilize dilute suspensions of micronized bioactive agents. In such implementations, perforated microstructures can be added to increase the volume of particles in the suspension, thereby increasing the stability of the suspensions upon thickening or settling. Furthermore, in these embodiments, the introduced microstructures can also act to prevent close contact (aggregation) of micronized particle structures. It should be clear that the perforated microstructures in such embodiments do not necessarily contain a bioactive agent. In fact, they can be simply formed exclusively from various additives, including surfactants.

Those skilled in the art will further appreciate that the stabilized suspensions or dispersions of the present invention can be prepared by dispersing the microstructures in selected suspension media, which can then be poured into a vessel or tank. In this respect, the stabilized preparations according to the present invention can be prepared by simply combining the components in sufficient amounts to produce the final desired concentration of the dispersion. Although the microstructures are easily dispersed without the aid of mechanical energy (e.g. by means of sonication, which is contemplated, especially for the formation of stable and reverse emulsions). Alternatively, the components can be mixed by simple shaking or with the help of some other type of mixing. It is recommended that the procedure is carried out in anhydrous conditions in order to avoid any undesirable effect of moisture on the stability of the suspension. Once formed, the dispersion has a reduced tendency to flocculation and sedimentation.

As indicated throughout this description, the dispersions of the present invention are preferably stabilized. In a broader sense, the term "stabilized dispersion" is considered to mean any dispersion that resists aggregation, flocculation, or thickening to the extent required to create conditions for effective delivery of a bioactive agent. While it will be apparent to those skilled in the art that there are a number of methods that can be used to achieve the stability of a given dispersion, the preferred method for use in connection with the present invention involves determining the thickening or settling time using a photo-sedimentation method. As seen in Example IX and on si. 2, The manual procedure consists of subjecting the suspended particles to centrifugal force and measuring the absorption of the suspension as a function of time. A rapid decrease in absorbance indicates a suspension of poor stability. This is disclosed so that those skilled in the art will be able to apply the procedure to specific suspensions without undue experimentation.

For use with the present invention, thickening time will be defined as the time it takes for the suspended drug particles to thicken to 1/2 the volume of the suspension medium. Similarly, the settling time can be defined as the time for the particles to settle to 1/2 the volume of the liquid medium. In addition to photo-sedimentation, presented here, a relatively simple way to determine the thickening time of a preparation is by placing a suspension of particles in sealed glass jars. Jars are shaken or shaken to obtain relatively homogeneous suspensions, which are then left and observed using appropriate instruments or only visually. The time required for the suspended particles to thicken to 1/2 the volume of the suspension (ie rise to half the height of the suspension medium), or to settle to 1/2 the volume (ie to settle to the bottom of the jar) is recorded. Suspension formulations with a thickening time of more than 1 minute are recommended and considered sufficiently stable. Even more recommended are stabilized dispersions with a thickening time of more than 1, 2, 5, 10, 15, 20 or 30 minutes. In particularly recommended embodiments, the stabilized dispersions have thickening times longer than 1, 1, 5, 2, 2, 5 or 3 hours. Essentially the same settling times indicate the compatibility of these dispersions.

As discussed herein, the stabilized dispersions disclosed herein are preferably administered via the nasal or pulmonary route to a patient by aerosolization using a metered dose inhaler. The use of such stabilized preparations provides better reproducibility of doses and improved deposition, described above. They are MDIs

are well known in the art and can be readily used to provide the published dispersions without unnecessary experimentation. Inhalation-activated MDIs, as well as those with other enhancements that have been, or will be, are also compatible with stabilized dispersions and with this invention and, as such, are contemplated as part thereof. However, it should be noted that in preferred embodiments, stabilized dispersions can be administered by MDI using a number of different routes, including, but not limited to, topical, pulmonary, nasal, and oral. It will be clear to those skilled in the art that these routes are well known and that dosing and administration can be easily accomplished with the stabilized dispersions of the present invention.

Carriers with MDI usually contain a vessel or tank, capable of withstanding the vapor pressure of the propellant and as such, plastic or plastic-coated glass bottles, or more preferably metal, can be e.g. made of aluminum, which can optionally be anodized, covered with varnish or plastic, whereby such a container is closed with a dosing valve. Dosing valves are designed in such a way that they pass a measured amount of formulation during each activation. This valve also contains a gasket to prevent fuel from leaking out of it. The gasket may be of any suitable elastomer such as low density polyethylene, chlorobutyl, black or white butadiene-acrylonitrile rubber, butyl rubber, and neoprene. Suitable valves are commercially available from manufacturers known in the aerosol industry, eg, Valois, France (eg DF10, DF30. DF31/50 ACT, DF60), Bespak plc. LTK (eg BK300, BK356) and 3M-Neotechnic Ltd., England (eg Spraymiser).

Each filled container is delivered to a suitable channeled device or actuator to form a measured dose for inhaler administration of the drug into the patient's lungs or nasal cavity. Recommended channeled devices include, for example, an actuator with a valve and a cylindrical or conical conduit, through which the drug can be administered from a filled reservoir via a dosing valve, through the patient's nose or mouth, eg, through a mouthpiece. Metered dose inhalers are designed to deliver doses of a fixed volume of drug with each actuation, such as in the range of 10 to 5000 micrograms of bioactive agent with each actuation. Typically, one filled reservoir provides dozens, even hundreds of doses.

With respect to MDI, an advantage of the present invention is that any bioactively compatible suspending medium with sufficient vapor pressure can serve as a propellant. Particularly recommended suspension media are compatible for use with metered dose inhalers. This means, they will be able to create aerosols upon activation of the dosing valve and associated pressure creation. In the general case, the chosen suspension medium should be compatible (ie, relatively non-toxic or non-reactive with the suspended perforated microstructures of the bioactive agent). Recommended suspension medium will not act as a suitable solvent for any component with perforated microspheres. Selected embodiments of the present invention contain suspension media from the group consisting of fluorocarbons (including those substituted with other halogens, hydrofluoroalkanes, perfluorocarbons, hydrocarbons, alcohols, ethers or combinations thereof). It will be clear that the suspension medium may contain a mixture of various compounds, selected to achieve specific characteristics.

Particularly preferred propellants for use with the MDI suspension media of the present invention are gases that can be converted into a liquid state at room temperature and, after inhalation or topical administration, are safe, toxicologically harmless and without side effects. In this regard, compatible propellants include any hydrocarbon, fluorocarbon, hydrogen fluorocarbon, or mixture thereof, of sufficient vapor pressure to effectively create an aerosol upon actuation of the metered dose inhaler. Propellants, typically called hydrofluoroalkanes or HFAs are particularly recommended. Suitable propellants are, for example, short chain hydrocarbons, C1-C4 hydrogen-containing chlorofluorocarbons, such as CH2CIF, CCI2F2CHCIF, CF3CHCIF, CHF2CCIF2, CHCIFCHF2, CF2CH2CI, and CCIF2CH3; C1-C4 hydrogen-containing fluorocarbons (eg HFA) such as CHF2CHF2, CF2CH2F, CHF2H3 and CF2CHCF2; and perfluorocarbons such as CF2CF2 and CF2CF2CF2. It is recommended to use only one perfluorocarbon or fluorocarbon with hydrogen content as a propellant. Especially recommended as propellants are 1, 1, 1, 2-tetrafluoroethane (CF3Ch2F), HFA-134a and 1, 1, 1, 2, 3, 3, 3-heptafluoro-n-propane (CF2CHCF2, HFA-227), perfluoroethane, monochlorodifluoromethane, 1, 1-difluoroethane and their combinations. It is desirable that the formulations do not contain components that destroy atmospheric ozone. It is especially desirable that the formulations practically do not contain chlorofluorocarbons, such as CCI2F, CCI2F and CF3CCI3

Specific fluorocarbons, or classes of fluorinated compounds, useful in suspension media include, but are not limited to, fluoroheptane, fluorocycloheptane, fluoromethylcycloheptane, fluorohexane, fluorocyclohexane, fluoropentane, fluorocyclopentane, fluoromethylcyclopentane, fluoromethylcyclopentane, fluoromethylcyclobutane, fluorodimethylcyclobutane, fluoromethylcyclobutane, fluorobutane, fluorocyclobutane, fluoropropane, fluoroethers, fluoropolyethers and fluoroethylamines. It will be clear that these compounds can be used alone or in combination with more volatile propellants. A clear advantage is that these compounds are generally harmless to the environment and biologically non-reactive.

In addition to the aforementioned fluorocarbons and hydrofluoroalkanes, various chlorofluorocarbons and substituted fluorinated compounds can also be used as suspending media in accordance with the present invention. In this regard, FC-11 (CCI3F), FC-11B1 (CBrCI2F), FC-11B2 (CBT2CIF), FC12B2 (CF2Br2), FC21 (CHCI2F), FC21B1 (CHBrCIF), FC21B2 (CHBr2F), FC31B1 CH2BrF), FC113A (CCI3F3), FC-122 (CCI2CHCI2), FC-123 (CF3CHCI2), FC-132 (CHCIFHCIF), FC-133 (CHCIFCHF2), FC-141 (CH2CICHCIF), FC-141B (CCI2CH3), FC-142 ( CHF2CH2CI), FC-151 (CH2FCH2CI), FC-152 (CH2FCH2F), FC-1112 (CCIF = CCIF), FC-1121 (CHCI=CFCI) and FC-1131 (CGCI=CHF), are all compatible with those given here data, despite possible accompanying environmental problems. As such, each of these compounds can be used, alone or in combination with the long compounds (ie, with less volatile fluorocarbons) to form the stabilized inhalable dispersions of this invention.

Along with the aforementioned embodiments, the stabilized dispersions of the present invention can also be used to create an aerosolized drug that can be administered through the pulmonary airways to a patient. Foggers are well known in the art and can be readily employed to provide the disclosed suspensions

without unnecessary experiments. Inhalation powered nebulizers and those incorporating other types of enhancements that have been, or will be, are also compatible with stabilized dispersions and are contemplated as part of the present invention.

Foggers work by forming aerosols, ie. they turn the liquid into small droplets, suspended in a gas, that can be inhaled. Here, the aerosolized drug, which should be administered (recommended through the lungs) will contain tiny droplets of suspension medium combined with perforated microstructures containing the bioactive agent. In such embodiments, the stabilized dispersions of the present invention will typically be fed into a liquid reservoir in conjunction with a nebulizer. The specific volumes of preparations prepared, methods of filling the reservoir, etc., will depend greatly on the choice of fogger and is well within the discretion of one skilled in the art. Of course, this invention is fully compatible with single-dose and multi-dose foggers.

Traditional prior art foggers contained aqueous solutions of selected pharmaceutical compounds. With these prior art nebulizer preparations, it has long been recognized that spoilage of the injected therapeutic compound can seriously compromise the efficacy of delivery. For example, with multi-dose nebulizer preparations, bacterial contamination is a constant problem. In addition, the solubilized drug can precipitate, or break down over time, adversely affecting drug administration. This is especially true for larger, more labile biopolymers, such as enzymes or other types of proteins. Precipitation of the ingested bioactive agent can lead to the growth of particles, which results in a significant decrease in penetration into the lungs and a corresponding decrease in bioavailability. Such dosage deficiencies significantly reduce the effectiveness of any treatment.

The present invention overcomes these and other difficulties in obtaining stable dispersions in a suspension medium, which preferably contains a fluorinated compound (eg, fluorochemical, fluorocarbon or perfluorocarbon). Particularly preferred embodiments of the present invention include fluorochemicals that are liquid at room temperature. As indicated above, the use of these compounds, either in the continuous phase or in the form of a suspension medium, offers several advantages over the liquid preparations of the prior art. In this regard, it is well known that many fluorochemicals have a proven history and biocompatibility in the lung. Furthermore, in contrast to aqueous solutions, fluorochemicals do not adversely affect shock gas exchange after pulmonary administration. Conversely, they may actually be able to enhance gas exchange and, due to their unique wetting properties, be able to carry an aerosolized stream of particles deeper into the lungs, thereby improving systemic delivery of the desired pharmaceutical compound. In addition, the relatively neutral (non-reactive) nature of fluorochemicals acts to slow down any degradation of the bioactive agent involved. Finally, many fluorochemicals are bacteriostatic, reducing the potential for microbial growth in compatible fogging devices.

In any case, aerosolization in nebulizers typically requires the input of energy to create increased droplet surface area and, in some cases, provide transport of the atomized and aerosolized drug.

One of the most common methods of aerosolization is pushing a stream of fluid through a single nozzle, which creates droplets. In the case of nebulizer administration, supplemental energy is usually supplied to create droplets small enough to be transported deep into the lungs. Thus, supplemental energy is required, such as obtained from high-velocity gas or a piezoelectric crystal. Two types of nebulizers, jet nebulizers and ultrasonic nebulizers, are based on the previously mentioned procedures for providing energy allowance to the fluid during atomization.

With respect to pulmonary delivery of bioactive agents into the systemic circulation by nebulizers, recent research has focused on the use of portable ultrasonic nebulizers, also called metered solution nebulizers. These devices, commonly referred to as single-bolus nebulizers, aerosolize a single dose of drug in an aqueous solution with particles of a size effective for deep lung penetration in one or two inhalations. These devices fall into three broad categories. The first category contains pure one-stage bolus nebulizers, such as those described by Motterlein, et al., (J. Aerosol Med., 1988,

1; 231). In the second category, the desired amount of aerosol cloud can be produced by blowing through the microchannels of foggers, such as those described in Pat. US no. 3, 812. 854. Finally, the third category comprises the devices disclosed by Robertson, et al., (WO 92/11050) which describes the cyclic pressurization of a single bolus nebulizer. Each of the aforementioned references is incorporated herein in its entirety. Most devices are manually operated, but there are some that are powered by inhalation. They do the latter by releasing an aerosol when the device senses that the patient is inhaling. Inhalation-activated devices can be linked in line with a single fan, which releases an aerosol into a stream containing inhaled gases for the patient.

Regardless of which type of device is used, the advantage of this invention is that bioactive non-aqueous compounds can be used as suspension media. It is recommended that they are capable of creating an aerosol when energized. In the general case, the chosen suspension media should be biocompatible (ie, relatively non-toxic and non-reactive with regard to suspended perforated microstructures with the content of a bioactive agent). Preferred embodiments contain suspension media selected from the group consisting of fluorochemicals, fluorocarbons (including those substituted with other halogens), perfluorocarbons, di-block fluorocarbons/hydrocarbons, hydrocarbons, alcohols, ethers, and combinations thereof. It will be appreciated that the suspension medium may contain a mixture of different compounds, selected to impart specific characteristics. It will also be clear that the perforated microstructures are preferably insoluble in the suspension medium, which contributes to the stabilization of the drug particles and effectively protects the selected bioactive agent from degradation, which could happen during prolonged storage in an aqueous solution. In the recommended implementations, the selected suspension medium is bacteriostatic. The suspension formulation also protects the bioactive agent from degradation during the fogging process.

As indicated above, the suspension media may contain one or more different compounds, including hydrocarbons, fluorocarbons or hydrocarbons/fluorocarbon di-blocks. In general, the hydrocarbons or highly fluorinated or perfluorinated compounds in question may be linear, branched, or saturated or unsaturated compounds. Derivatives of the usual structure of these fluorochemicals and hydrocarbons are also contemplated within the scope of this invention. Selected embodiments containing these fully or partially fluorinated compounds may contain one or more heteroatoms and/or bromine or chlorine atoms. Preferably these fluorochemicals contain from 2 to 16 carbon atoms and include, but are not limited to, linear, cyclic or polycyclic perfluorocarbons, bis(perfluoroalct1)alkanes, perfluoroethers, perfluoroamines, perfluoroalkyl bromides and perfluoroalkyl chlorides, such as dichloroacetate. Particularly recommended fluorinated compounds for use in suspension media may include perfluorooctyl bromide C8F17Br (PFOB or perflubron), dichlorofluorooctane CgF16CI2 and hydrofluorooctyl ethane C6F17C2H5 (PFDE). In other embodiments, the use of perfluorohexane or perfluoropentane as suspending media is particularly recommended.

More generally, examples of fluorochemicals contemplated for use with the present invention typically include halogenated fluorochemicals (ie, CnF2n+1X, XCnF2nX, where n = 2 - 10, X = Br, Cl or J), and in particular, J-bromo- F-butane (nC4F8Br), 1-bromo-F-heptane (nC7F16Br), 1, 4-dibromo-F-butane and 1, 6-dibromo-F-hexane, 1-bromo-F-hexane (nC6F13Br). Other useful brominated fluorochemicals are disclosed in Pat. US no. 3, 975. 512 by Lang and are incorporated herein by reference. Special fluorochemicals with chloride substituents, such as perfluoroacrylic chloride (nC5F17CI), 1,8-dichloro-F-octane (nCIC6F16CI), 1,6-dichloro-F-hexane (nCIC6F12CI), and 1,4-dichloro-f-butane ( nCIC4F8CI) are also recommended.

Fluorocarbons, fluorocarbon-hydrocarbon compounds and halogenated fluorochemicals containing other linking groups, such as esters, thioethers and amines, are therefore suitable as suspending media in the present invention. For example, compounds of the general formula CnF2n+lOCmF2m+1 M CnF2n + lCH=CHCmF2m+i (as, e.g., C4FgCH=CHC4Fg(F-44E), iC2F8CH=CHC5F-i35 (F-136E), and C6F13CH=CHC6Fi 3 (F-66E). where n and m are the same or different, and n and m are integers from about 2 to about 12, are compatible according to the instructions given herein. Useful fluorochemical-hydrocarbon diblock- and tribi- compounds include those of the general formula (--nF2n+lCmF2m+1 ' ^n^2n+lCm^2m+1 . where n = 2 -12; m = 2 -16, or CpH2p+-|CnF2nCmFl2m+1. where p = 1-12, m = 1 - 12 and n = 2 - 12. Recommended compounds of this type include: CgFi 7C2H5 ,

^6Fl3C-] 0H21, C8F17C8H17, CgFCHCgH-13 and C8F-|7CH=CGCioH21 Substituted teres and polyethers (ie XCnF2nOCmF2mX. XCFOCnF2nOCF2X, where n and m = 1 - 4, X = Br. Cl or J) and fluorochemical-carbon- hydrogen diblock-or triblock-ethers (i.e. CnF2n+lOCmH2m+1.9^e are n=2-10, m = 2-16, or CpH2p+-|OCm- H2m+1. where p = 2 - 12, m = 1 -12 and n = 2 - 12) can also be used, as well as CnF2n+lOCmF2mO~ CpH2p+1 , where n, m and p are 1 - 12. Furthermore, depending on the application, perfluoroalkylated ethers or polyethers can be compatible with published dispersions .

Polycyclic and cyclic fluorochemicals, such as C10F18 (F-decalin or perfluorodecalin, perfluoroperhydrophenanthrene, perfluorotetramethylcyclohexane (AP-144), and perfluoro n-butyldecalin are also within the scope of this invention. Additional useful fluorochemicals include perfluorinated amines, such as F-tripropylamine ("FTPA ") and F-tributylamine ("FTBA"), F-4-methyloctahydroquinolisine ("FMOQ"), f-N-methyldecahydroisoquinoline ("FKIO"), F-N-methyldecahydroquinoline ("FHQ"), F-N-cyclohexylpyrrolidine ("FCHP" ) and F-2-butyltetrahydrofuran (FC-75" or "FC-77"). Still other useful compounds include perfluorophanathrane, perfluoromethyldecalin, perfluorodimethylcyclohexane, perfluoromethyldecalin, perfluoroethyldecalin, perfluoromethyladamantane, perfluorodimethyladamantane. Other fluorochemicals under consideration . fluorochemicals and are used conveniently within the scope of this invention. As such, any of the foregoing compounds may be used, alone or in combination with all other compounds, to form the stabilized dispersions of the present invention.

Certain fluorocarbons, or classes of fluorinated compounds, that may be useful may include, but are not limited to, fluoroheptane, fluorocycloheptane, fluoromethylcycloheptane, fluorohexane, fluorocyclohexane, fluoropentane, fluorocyclopentane, fluoromethylcyclopentane, fluorodimethylcyclopentane, fluoromethylcyclobutane, fluorodimethylcyclobutane, fluorotriethylcyclobutane, fluorobutane, fluorocyclobutane, fluoropropane, fluoroethers, fluoropolyesters and fluoroethylamines. These compounds are generally harmless to the environment and biologically neutral (non-reactive).

While any liquid compound capable of forming an aerosol upon application of energy may be used within the scope of this invention, the suspension media selected will preferably possess a vapor pressure of about 5 bar and above and preferably less than about 2 bar. Unless otherwise specified, the stated vapor pressures are measured at 25'C. In other embodiments, preferred suspension compounds will have a vapor pressure on the order of about 5 Torr to about 700 Torr (0.0068 to about 0.95 bar), with more preferred compounds having a vapor pressure of about 8 Torr to about 600 Torr (0.011 to about 0.82 bar), and more preferably with that pressure from about 10 to about 350 Torr (0.0136 to about 0.48 bar). Such suspension media will be used with foggers with compressed air, ultrasonic foggers or mechanical atomizers, in order to obtain effective ventilation therapy. Moreover, more volatile compounds can be mixed with components that have vapor pressure to obtain suspension media with certain physical characteristics with the aim of further improving the stability or increasing the bioavailability of the dispersed bioactive agent.

Other embodiments of the present invention are directed toward nebulizers and will contain suspension media that boil at selected temperatures lower than ambient (ie, 1 bar). For example, preferred embodiments will contain suspension media compounds that boil above 0°C, above 5°C, above 15°C, or above 20°C. In other embodiments, the suspending medium compounds may boil at or above 25°C or at or above about 30°C. In still other embodiments, the selected suspension medium compounds may boil at or above human body temperature (ie, 37°C), above 45°C, 55°C, 65°C, 75°C, 85°C, or above 100°C. C.

Along with MDI devices and nebulizers, it will be appreciated that the stabilized dispersions of the present invention may be used in conjunction with liquid dose devices, or LDIs. Liquid dose devices involve direct administration of stabilized dispersions into the lungs. In this regard, direct delivery of bioactive compounds to the lungs is particularly effective in Iretman's disease, where poor vascular circulation in the lungs reduces the effectiveness of intravenous drug administration. Regarding LDI, stabilized dispersions are recommended to be used in connection with partial or total liquid ventilation. Moreover, the present invention may further comprise the introduction of a therapeutically useful amount of a physiologically acceptable gas (such as nitrous oxide or oxygen) into the pharmaceutical microstructure before, during or after administration.

In LDI, the dispersions of the present invention can be administered to the lungs using the pulmonary route of administration. Those skilled in the art will appreciate that the term "pulmonary administration route", as used herein, will be understood broadly to include any devices or apparatus, or components thereof, that allow fluid to be introduced or administered into the lungs. In this respect, the pulmonary route of administration or simply the route of administration should be understood to mean any opening, volume, catheter, tube, line, syringe, actuator, mouth piece, endotracheal tube or bronchoscope, which allows the administration or introduction of the disclosed dispersions into at least one part of the patient's pulmonary airways, who needs it. It will be understood that the route of administration may or may not be associated with a liquid or gas ventilator.

In particularly recommended procedures, the route of administration will consist of an endotracheal tube or a bronchoscope.

It must be emphasized here that the dispersions according to the present invention can be administered to ventilated (ie attached to a mechanical ventilator) or non-ventilated patients (eg those who are breathing spontaneously). Accordingly, in preferred embodiments, the methods and systems of the present invention may include the use or inclusion of a mechanical ventilator. Furthermore, the stabilized dispersions according to the present invention can also be used as a lavage to remove harmful residues from the lungs, or for diagnostic lavage. In any event, the introduction of fluids, especially fluorochemicals, into the lungs of a patient is well known and can be performed by one skilled in the art with a valid prescription, without unnecessary experimentation.

Those skilled in the art will appreciate that LDI-compatible suspension media similar to those described above are used with foggers. Therefore, for the purposes of this application, LDI-compatible suspension media should be equivalent to those listed above for use with foggers. In any case, it will be clear that in particularly recommended embodiments of LDI, the selected suspension media contain a fluorochemical that is liquid at room conditions.

It will be understood that in connection with the present invention, the disclosed dispersions are preferably administered directly to at least one portion of the pulmonary airways of a mammal. As used herein, the terms "direct injection" or "direct administration" are to be understood as the introduction of a stabilized dispersion into the pulmonary cavity of a mammal. That is, the dispersion will preferably be administered through the patient's trachea, into the lungs, as a relatively free passage for liquid dispersions, through the administration line and into the pulmonary airways. In this regard, dispersion flow can be greatly assisted or obtained by introducing pressure, e.g. from one pump, or by compression from one syringe. In any case, the amount of dispersion given can be monitored by mechanical devices, such as flowmeters or visually.

While stabilized dispersions can be administered up to the limit of residual functional lung capacity, it will be appreciated that the embodiments selected will involve pulmonary administration of much smaller volumes (eg, on the order of one milliliter or less). For example, depending on the disease being treated, the given volume will be on the order of 1, 2, 5, 10, 50, 100, 200 or 500 ml. In recommended designs, the liquid volume is less than 0.25 or 0.5% FRC. In particularly recommended discharges, the liquid volume is 0.1% FRC or less. With regard to the administration of relatively small volumes of stabilized dispersions, it will be clear that the wetting and spreading characteristics of the suspension medium (especially fluorochemicals) will facilitate the distribution of the bioactive agent in the lungs. However, in other embodiments, it may be preferable to provide suspension volumes greater than 0.5%, 75% or 0.9% FRC. In this case, treatment with LDI, as reported here, represents a new alternative for critically ill patients. who are on mechanical ventilators and creates the possibility of treating less sick patients with bronchoscopic administration. It will also be appreciated that other components may be included in the stabilized dispersions of the present invention. For example, orthotics, stabilizers, chelators, buffers, viscosity modifiers, salts and sugars may also be added to fine-tune the stabilized dispersions for longest shelf life and ease of administration. Such components can be added directly to the suspension medium or combined with perforated microstructures. Considerations such as sterility, isotonicity, and biocompatibility may govern the use of common additives to published preparations. The use of such agents will be understood by those skilled in the art and specific amounts, ratios and types of agents can be determined empirically without undue experimentation.

Moreover, while the stabilized dispersions according to this invention are particularly suitable for pulmonary administration of bioactive agents, they can also be used for local and systemic administration of compounds to any part of the patient's body. Accordingly, it should be noted that, in preferred embodiments, the formulations may be administered using a variety of routes including, but not limited to, gastrointestinal tract, respiratory tract, topical, intramuscular, intraperoneal, nasal, vaginal, rectal, oral, oral, or through the eyes. More generally, the stabilized dispersions of the present invention can be used to administer agents locally or by administration to a non-pulmonary body cavity. In recommended implementations, the body cavity will be selected from the group consisting of: peritoneum, sinuses, rectum, urethra, gastrointestinal tract, nasal cavity, vagina, oral cavity, oral cavity, buccal cavity and pleura. In addition to other indications, stabilized dispersions containing the appropriate bioactive agent (for example, some antibiotic or anti-inflammatory agent) can be used for the treatment of eye infections, sinusitis, ear canal infections, and even infections or diseases of the gastrointestinal tract. With regard to the latter, the dispersions of the present invention can be used to selectively deliver pharmaceutical compounds to the gastric mucosa for the treatment of H. pylori infections or other related diseases.

With respect to the perforated microstructure powders and stabilized dispersions disclosed herein, it will be apparent to those skilled in the art that the same can be successfully administered to a physician or other healthcare professional in sterile, prepackaged or kit form. More particularly, the formulations may be provided as stable powders, ready for administration to the patient. In contrast, they can be prepared as separate, ready to mix components. When prepared in ready-to-use form, powders or dispersions can be packaged in single-use packages, or in tanks, as well as multi-compartment vessels or tanks. Alternatively, the vessel or reservoir may be combined with the selected inhaler delivery device and co-irrigated as described herein. When prepared as individual components (eg as powdered microspheres and as pure suspension media), stabilized preparations can be prepared at any time before use by simply combining the contents of these containers, according to the instructions. Therefore, such kits may contain a number of prepackaged units, ready to be mixed, so that the user can prepare them for administration as needed.

While preferred embodiments of the present invention include powders and stabilized dispersions for use in pharmaceutical applications, it will be understood that the perforated microstructures and disclosed dispersions may be used for a number of non-pharmaceutical applications. That is, this invention provides perforated microstructures, which have a wide range of applications, where the powder is suspended and/or aerosolized. In particular, this invention is particularly effective where the active or bioactive agent needs to be dissolved, suspended or solubilized as quickly as possible. Increasing the surface area of porous microparticles or introducing suitable additives, as described here, will result in improved dispersibility and/or stability of suspensions. In this regard, rapid dispersion application includes, but is not limited to, in: detergents, dishwashing detergents, food sweeteners, spices, flavors, mineral flotation detergents, thickeners, foliar fertilizers, phytohormones, insect pheromones, repellents means against insects, protective means for domestic animals, fungicides, disinfectants, deodorants, etc.

Applications requiring finely divided particles in non-aqueous suspensions (ie, solid liquid or gaseous aerosols) are also contemplated to be within the scope of this invention. As described here, the use of perforated microstructures to create "homodispersion" minimizes interactions between particles. As such, the perforated microparticles and stabilized suspensions of the present invention are particularly compatible for applications requiring: inorganic pig. mints, paints, inks, stains, explosives, pyrotechnics, adsorbents, absorbents, catalysts, nuclear agents, polymers, resins, insulators, fillers, etc. The present invention provides an advantage over the prior art for applications requiring aerosolization or atomization. In such pharmaceutical applications, the preparations can be used in the form of liquid suspensions (as with some propellant) or as a dry powder. Preferred embodiments comprising perforated microstructures as described herein include, but are not limited to, ink jet formulations, powder coating, spray painting, spray pesticides, etc.

The preceding descriptions will be better understood with reference to the following Examples. These Examples, however, are only representative of recommended practices for carrying out the present invention and should not be construed as limiting the scope of the present invention.

Preparation of hollow porous particles from gentamicin sulfate by spray drying

40 to 60 ml of the following solutions were prepared for spray drying:

50% wt. of hydrogenated phosphatidylcholine, E -100 - 3 (Lipoid KG, Ludwigshafen, Germany)

50% by weight. gentamicin sulfate (Amresco, Solon, Ohio, USA) perfluorooctyl bromide, Perflubron (NMK, Japan) deionized water.

Perforated microstructures containing gentamicin sulfate were prepared by spray drying technique using B-191 Mini Spray-Drier (Buchi, Flavil, Switzerland), under the following conditions:

suction: 100 %, inlet temperature: 85* C; outlet temperature: 61° C; feed pump: 10%; N2 flow: 2800 l/h. Variations of powder porosity as a function of propellant concentration were tested

Emulsions of perfluorocarbon in water and perfluorooctyl bromide with a content of 1: 1 by weight. /weight of phosphatidylcholine (PC) and gentamicin sulfate were prepared by changing only the PFC/PC ratio. 1.3 g of hydrogenated phosphatidylcholine from eggs was dispersed in 25 ml of deionized water, using an Ultra-Turex mixer (model T-25) at 8000 rpm for 2-5 minutes (T = 60-70⁰C) - Range from 0 to 40 g of perfluorocarbon was added drop by drop while stirring (T = 60-70'C). The resulting coarse emulsions were then homogenized using an Avestin (Ottawa, Canada, Canadian homogenizer, at 15000 psi (about 1040 bar)) in 5 passes. Gentamicin sulfate was then dissolved in about 4 to 6 ml of deionized water and then mixed with the perflubron emulsion under the conditions given above. A free-flowing pale yellow powder was obtained for all formulations containing perflubron. The yield of each of the different formulations was from 35 to 60%.

II

Morphology of spray-dried gentamicin sulfate powders

A strong dependence of the powder morphology, its porosity and production yield was observed as a function of the PFC/PC ratio by scanning electron microscopy (SEM). A series of SEM micrographs illustrating these observations, labeled 1A1 to 1F1, is shown in the left column of SI. 1. As can be seen in those micrographs, the porosity and roughness of the surface, the number and size of the pores, increased with the increase of the PFC/PC ratio. For example, formulations without perfluorooctyl bromide gave microstructures that easily agglomerated and easily adhered to glass jar surfaces. Similarly, smooth, spherical microparticles were obtained at relatively low ratios (PFC/PC = 1.1 or 2, 2) propellant. As the PFC/PC ratio increased, the porosity and surface roughness increased dramatically.

As shown in the right column of SI. 1, the hollow nature of the microstructures is also improved by adding more propellant. More specifically, a series of 6 micrographs labeled 1A2 to 1F2

shows cross-sections of crushed microstructures, shown by transmission electron microscopy (TEM). Each of these images was produced using the microstructure preparation as for the corresponding SEM images in the left column. Both the hollow nature as well as the wall thickness of the obtained perforated microstructures appeared to be highly dependent on the concentration of the selected propellant. This means, the hollow nature of the preparations seems to increase and the thickness of the walls decreases with increasing PFC/PC ratio. As can be seen in fig. 1A2 to 1C2, essentially full structure was obtained with little or no fluorocarbon propellant. In contrast, perforated microstructures produced at relatively high PFC/PC ratios of about 45 (see Fig. 1F2) became extremely hollow, with a relatively thin wall in the range of about 43.4 to 261 nm. Both types of particles are compatible for use in the formulations of the present invention.

Preparation of gentamicin sulfate particles prepared by spray drying

with various propellants

40 ml of the following solutions were prepared for spray drying:

50% wt. of hydrogenated phosphatidylcholine, E - 100 - 3 (Lipoid KG, Ludwigshafen, Germany)

50 % tej. gentamicin sulfate (Amresco, Solon, Ohio, SAD) deionizovana voda.

Pogonska means:

perfluorodekalin, FDC (Air products, Allenton, PA, SAD) perfluorooktil bromid, Perflubron (Atochem, Pariz, Francuska) perfluoroheksan, PHF (3M, St. Pol. MN, SAD)

1, 1, 2-trihlorotrifluoroetan, Freon 113 (Baxter, McGavv park, IL, SAD).

Hollow porous microspheres with a typical hydrophilic drug, e.g., gentamicin sulfate, were prepared by spray drying. The propellant in these formulations consisted of emulsified fluorochemical (FC) oil. Emulsions were prepared with the following FCs: PFH, Freon 113, Perflubron and FDC 1. 3 g of hydrogenated phosphatidylcholine from eggs were dispersed in 25 ml of deionized water using an Ultra-Turax mixer (model T-25) at 8000 rpm for 2 to 5 minutes (T = 60-70⁰C). 25 g of FC was added dropwise while stirring (T = 60-70⁰C). After the addition was complete, the FC in water emulsion was mixed for a total of no less than 4 minutes. The resulting emulsions were further processed using an Avestin (Ottawa, Canada, Canadian high pressure homogenizer) at 15000 psi (about 1040 bar) in 6 passes. Gentamicin sulfate was dissolved in about 4 to 5 ml of deionized water and then mixed with FC emulsion. Gentamicin powders were obtained by spray drying (Buchi, 191 Mini Spray Dryer). Each emulsion was fed at 2.5 ml/min. The inlet and outlet temperatures to the dryer were 85 and 65" C, respectively. The fogging and suction air

volumes were 2800 l/h and 100%, respectively.

A free-flowing pale yellow powder was obtained for all formulations. The yield for various formulations ranged from 35 to 80%. Different gentamicin sulfate powders had measured mean particle diameters between 1.52 and 4.91 microns.

IV

Effect of propellant on the morphology of spray-dried gentamicin sulfate powders

A strong dependence of powder morphology, porosity and production yield (the amount of powder captured in the cyclone) as a function of the boiling point of the propellant was observed. In this regard, the powders produced in Example III were observed by scanning electron microscopy. Spray-drying emulsions of fluorochemicals (FC) boiling below 55°C exit temperature (eg, perfluorohexane (PFH) or Freon 113) produced amorphous powders (shrunk or pumped), with little or no pores . However, higher boiling point emulsion formulations of FC (eg, perflubron, perfluorodecalin, FDC) yielded spherical porous particles. Powders produced with higher boiling point propellants had production yields about 2 times higher than those with lower boiling point propellants. Selected propellants and their keying points are given in Table II immediately below.

Example IV shows that the physical characteristics of the propellant (eg, pour point) significantly affect the ability to change microstructure morphology and porosity by changing the conditions and nature of the propellant.

IN

Preparation of spray-dried albuterol sulfate particles using various propellants About 185 ml of the following solutions were prepared for spray drying:

49% wt. of hydrogenated phosphatidylcholine, E - 100 - 3 (Lipoid KG, Ludwigshafen, Germany)

50% by weight. albuterol sulfate (Accurate Chemical, Mesbury, NY, USA)

1 % tej. Fotoxamer 188, NF grade (Mount Olive, NJ, SAD) deionized water.

Pogonska means:

perfouorodekalin, FDC (Air products, Allentom, PA, SAD) perfluorooktil bromid, Perflubron (Atochem, Pariz, Francuska) perfluorobutil etan F4H2 (F-Tech, Japan) perfluorobutil amin FTBA

Albuterol sulfate powder was prepared by spray drying using a B-191 Mni Spray Drier (Buchi, Flavil, Switzerland) under the following conditions:

Suction: 100%, inlet temperature: 85'C outlet temperature: 61'C feed pump: 2.5 l/min, N2 flow: 47 l/min.

The starting solution was prepared by mixing solutions A and B before spray drying.

Solution A: 20 g of water was used to dissolve 1.0 g of albuterol sulfate and 0.021 g of Poloxamer 188.

Solution B: represents an emulsion of fluorocarbon in water, stabilized by phospholipid, which was prepared as follows. Hydrogenated phosphatidylcholine (1.0 g) was homogenized in 150 g of hot deionized water (T = 50 - 60⁰C) using an Ultra-Turax blender (model T-25) at 8000 rpm, for 2 to 5 minutes (T = 6070⁰C ). 25 g of Perflubron (Atochem, Paris) was added dropwise while stirring. After addition, the emulsion of fluorochemical in water was mixed for at least 4 minutes. The resulting emulsion was then processed using an Avestin (Ottawa, Canada) high pressure homogenizer at 15000 psi (about 1040 bar) in 5 passes. Solutions A and B were mixed and fed into a spray dryer under the conditions given above. A free-flowing white powder was collected from the cyclone, which is standard for this dryer. Albuterol sulfate powders have a measured mean particle diameter in the range of 1.28 to 2.77 microns, as determined by an Aerosizer (Amherst Process Instruments, Amherst, MA, USA). By SEM, albuteriol sulfate powders obtained by spray drying were spherical and highly porous.

Example V further demonstrates a wide variety of propellants that can be used to create perforated microparticles. A special advantage of this invention lies in the possibility to change the morphology of the structures and their porosity, by changing the formulations and spray drying conditions. Further, Example V demonstrates the diversity of the particles obtained by the present invention and the ability to efficiently contain a wide variety of pharmaceutical agents within them.

Preparation of hollow porous PVA particles by spray drying from water-in-oil emulsions

100 ml each of the following solutions were prepared for spray drying:

80% wt. bis-12-ethylhexyl sulfosuccinic sodium salt (Aerosol DT, Kodak, NY, USA)

20% wt. polyvinyl alcohol, average molecular weight 30,000 - 70,000 (Sigma Chemicals, Milwaukee, USA) carbon tetrachloride (Alckich Chemicals, Milwaukee, WI, USA) deionized water.

Aerosol particles of DT/polyvinyl alcohol were prepared by spray drying using a B-191 Mini Spray Drier (Buchi, Switzerland) under the following conditions:

Suction: 85%.

inlet temperature: 60⁰C

output - : 43⁰C

feed pump: 7.5 ml/minute

protok N2: 36 l/min.

Solution A: 20 g of water was used to dissolve 500 mg of polyvinyl alcohol A (PVA).

Solution B: represents an emulsion of carbon tetrachloride in water, stabilized with aerosol DT, which was prepared as follows. 2 g of aerosolized DT was dispersed in 80 g of carbon tetrachloride using an Ultra-Turax mixer (model T-25) at 8000 rpm for 2 to 5 minutes (T = 15 to 20'C). 20 g of 2.5 wt% PVA was added dropwise while stirring. After addition, the water-in-oil emulsion is mixed for at least 4 minutes (T = 15 to 20'C). The rest of the emulsion was then processed using an Avestin (Ottawa, Canada, Canadian high-pressure homogenizer) at 12,000 rpm in 2 passes. The emulsion was then fed into a spray dryer under the above conditions. A free-flowing white powder was collected from the cyclone. The aerosolized DT/PVA powder had a mean particle diameter of 5.28 0.27 microns, as measured by an Aerosizer (Amherst Process Instruments, Amherst, MA, USA). -

Example VI further shows the variety of emulsion systems (here, the reverse: water in oil), formulations and conditions, which can be used to obtain perforated microparticles. A special advantage of this invention is the ability to change the formulations and/or conditions for the production of preparations with microstructures of selected porosity. This principle is more closely illustrated in the following example.

VII

Preparation of hollow porous polycaprolactone particles by spray drying a water-in-oil emulsion 100 ml of the following solutions were prepared for spray drying:

80 % tež. sorbitan monostearata, Pan 60, (Alridch Chemicals, Milvoki, Wi, SAD)

20% wt. of polycaprolactone, average molecular weight = 65000 (Same firm as immediately above) carbon tetrachloride (-''- -''- -''- -''- -''- )

deionized water.

The Span 60/polycaprolactan cells were prepared for scattering by means of a b-191 Mini Stray-Drier (Buchi, Flavil, Switzerland)) under the following conditions:

Suction: 85% inlet temperature: 60'C outlet temperature: 38'C feed pump: 7.5 ml/min. N2 flow: 36 l/min.

An emulsion of water in carbon tetrachloride was prepared as follows. 2 g of Span 60 were dispersed in 80 g of carbon tetrachloride using an Ultra-Turax mixer (model T-25) at 8000 rpm for 2 to 5 minutes (T =

15 - 20'C). 20 g of deionized water was added dropwise while stirring. After addition, the water-in-oil emulsion was kneaded for a total of, but not less than, 4 minutes (Z = t5 - 20'C). The resulting emulsion was further processed with the help of an Avestin. a (Ottawa, Canada, Canada high. pressure homogenizer) at 12000 psi (about 830 bar) in 2 passes. 500 mg of polycaprolactone was added directly to the emulsion and mixed until complete dissolution. The emulsion was then fed into a spray pulverizer under the conditions described above. A free-flowing, white powder was collected from the cyclone. The resulting Špan 60/polycaprolactone powder had a mean measured particle diameter of 3.15 + 2.17 microns. Again, this example showed the applicability of this invention in terms of starting material, used to obtain the desired characteristics of perforated microstructures.

VIII

Preparation of hollow porous powder by spray drying gas-in-water emulsions The following solutions were prepared with water for injections:

Solution 1:

3.9% of the m-HES hydroxyethyl starch (Ajinomoto, Tokyo, _ Japan)

3, 25% wt. sodium chloride (Malinckrodt, St. Louis, MO. USA)

2, 83 % wt. sodium phosphate, dibasic, (Malinckrodt, St. Louis, MO, USA)

0.42% wt. sodium phosphate, monobasic (- '' - ).

Solution 2:

0, 46% weight. Poloxamer 188 (BASF, Mount Olive, NJ, SAD)

1, 35% wt. hydrogenated egg-derived phosphatidylcholine, EPC-3 (Lipoid KG, Ludwigshafen, Germany).

The ingredients of solution 1 were dissolved in warm water using a hand plate. The surfactants in solution 2 were dispersed in water using a high shear mixer. The solutions were combined and saturated with nitrogen before spray drying.

The resulting free-flowing product of hollow spherical particles had an average particle diameter of 2.8 + 1.6 microns. The particles were spherical and porous, as determined by SEM.

This example illustrated the fact that a wide variety of propellants (here nitrogen) can be used to obtain microstructures that possess the desired morphology. Indeed, one of the primary advantages of this invention is the ability to vary the conditions of formation, as well as to preserve the biological activity (ie of proteins), or to produce microstructures of selected porosity.

IX

Stability of suspensions of spray-dried gentamicin sulfate powders

The stability of the suspensions was determined as the resistance of the powders to thickening in a non-aqueous environment, using a dynamic photo-sedimentation procedure. Each sample was suspended in Perflubron at a concentration of 0.8 mg/ml. The densification rate was measured with a Koriba CAPA - 700 particle size analyzer using photosedimentation (Irwin, CA, USA), under the following conditions:

The suspended particles were subjected to centrifugal force and the absorption of the suspension was measured as a function of time. A rapid decrease in absorbance indicated a suspension of poor stability. The absorbance data were plotted as a function of time and the areas under the curves were integrated between 0.1 and 1.0 minutes, which was taken as a relative measure of stability. SI. 2 shows graphically the stability of suspensions as a function of PFC/PC ratio or porosity. In this case, porosity was found to increase with increasing PFC(PC. The highest suspension stability was observed for formulations with PFC/PC ratios between 3 and 16. For the most part, these formulations appeared stable for periods longer than 30 minutes, using visual procedures inspections. At points below those ratios, the suspension formulations flocculated rapidly, indicating reduced stability. Similar results were observed using the thickened layer thickness ratio measurement procedure, where suitable suspension stability was observed.

X

Preparation of spray-dried albuterol sulfate hollow porous particles

Albuterol sulfate hollow porous particles were prepared by spray drying using a B-191 Mini Spray Drier (Buchi, Flavil, Switzerland)) under the following conditions: suction: 100%, inlet temperature: 65*C; outlet temperature: 61⁰ C; feed pump: 10%; flow N2: 2800 Imin. The starting material in the form of a solution was prepared by mixing two solutions A and B immediately before spray drying.

Solution A: 20 g of water was used to dissolve 1 g of albuterol sulfate (Accurate Chemi

cals, Vestberi, NY, SAD) i 0, 021 f Poloxamer-a 188 NF grade (BASF, Mount Olive, NJ, SAD).

Solution B: An emulsion of fluorochemical in water, stabilized with phospholipid, was prepared as follows. Phospholipid, 1 g EPC - 100 - 3 (Lipoid KG, Ledvigshafen, Germany), was homogenized in 150 g of hot deionized water (T = 60 to 60⁰ C) using an Ultra-Turrax blender (model T-25) at 8000 rpm in the inlet for 2 to 5 minutes (T = 60 - 70⁰ C). 25 g of perfluorooctyl bromide (Atochem, Paris) was added dropwise while stirring. After the fluorocarbon was added, the emulsion was mixed for no less than 4 minutes. The obtained coarse emulsion was forced through a high pressure homogenizer (Avestin, Ottawa, Canada) at a pressure of 18000 psi (about 1240 bar) in 5 passes.

Solutions A and B were combined and fed into a spray dryer under the above conditions. A free-flowing white powder was collected from the cyclone. The hollow porous particles of albuterol sulfate had a mean aerodynamic diameter of 1.18 + 1.42 microns, determined by a time-of-flight analyzer (Aerosizer, Amherst Process instruments, Amherst, MA, USA). Scanning electron microscopy (SEM) showed that the powder is spherical and highly porous. The highest density of the powder is determined as less than 0.1 g/cm3.

This example serves to illustrate the inherent diversity of this invention as a drug delivery solution containing one or more pharmaceutical agents. This principle will be illustrated in the following example.

XI

Preparation of hollow porous BDP particles by spray drying

Perforated microstructures containing beclomethasone dipropionate (BDP) were prepared by spray drying using one B-191 Mini Spray Drier (Buchi, Flavil, Switzerland) under the following conditions: suction: 100%; inlet temperature: 65⁰C; outlet temperature: 61⁰C; feed pump: 10%; flow N2: 2800 l/min. The starting material was prepared using 0.11 g of lactose with a fluorocarbon emulsion in water, immediately before spray drying. The emulsion was prepared according to the text below.

74 mg BDP (Sigma Chemical Co., St. Luis, MO, SAD), 0, 5 g EPC -100 - 3 (Lipoid KG, Ludvigshafen,

Germany), 15 mg of sodium oleate (Sigma) and 7 mg of Poloxamer 188 (BASF, Mount Olive, NJ, USA) dissolved in 2 ml of hot methanol. Then the methanol was evaporated and a thin film of the phospholipid/steroid mixture was obtained. This mixture was then dispersed in 64 g of hot deionized water (T = 50 to 60⁰C) using an Ultra-Turrax mixer (model T-25) at 8000 rpm for 2 to 5 minutes (T = 60 - 70⁰C). 8 g of perflubron (Atochem, Paris) was added dropwise while stirring. After that, the emulsion was mixed for no less than 4 minutes. The resulting coarse emulsion was then forced through a high pressure homogenizer (Avestin, Ottawa, Canada) at 18000 psi (about 1240 bar) in 6 passes. This emulsion was then used to prepare the starting material, which was spray-dried as described above. A free-flowing white powder was collected from the cyclone. Hollow porous BDP particles had a mean density of less than 0.1 g/cm3.

XII

Preparation of hollow porous particles of cromaline sodium by spray drying

Perforated microstructures containing cromolyn sodium were prepared by spray drying using a B-191 Mini Spray-Drier (Buchi, Flavil, Sajcarska) under the following conditions: suction: 100%, inlet temperature: 85⁰C; outlet temperature: 61⁰C; feed pump: 10%; flow N2: 2800 l/min. The starting material was prepared by mixing solutions A and B immediately before spray drying.

Solution A: 20 g of water was used to dissolve 1 g of cromolyn sodium (Sigma Chenical Co., St. Louis, MO, USA) and 0.021 g of poloxamer 188 NF g-ade (BASF, Mount Olive, NJ , USA).

Compound B: A phospholipid-stabilized fluorocarbon-in-water emulsion was prepared as follows. Phospholipid, 1 g of EPC - 100 - 3 (Lipoid KG, Ludwigshafen, Germany) was homogenized in 150 g of hot water (T = 60-70'C). 27 g of perfluorodecalin (Air Products, Allenton, PA, USA) was added dropwise while stirring. After that, the emulsion was mixed for at least 4 minutes. The resulting coarse emulsion was forced through a high pressure homogenizer (Avestin, Ottawa, Canada) at 18000 psi (about 1240 bar) in 5 passes.

Solutions A and B were combined and fed into the spray dryer under the above conditions. A free-flowing pale yellow powder was collected from the cyclone. The hollow porous particles of cromolyn sodium had a mean aerodynamic diameter of 1.23 + 1.31 microns, as measured by an analytical time-of-flight method (Aerosizer, Amherst Process instruments, Amherst, MA, USA). As shown in fig. 3, SEM analysis showed that the powders were both hollow and porous. The mean density is defined as less than 0.1 g/cm3.

XIII

Preparation of Hollow Porous Dnase I Particles by Spray Drying Hollow porous particles of Dnase I were prepared by spray drying using a B-191 Mini

Spray-Drier dryer (Buchi, Flaviul, Switzerland) under the following conditions: suction: 100%; inlet temperature 80' C; outlet temperature: 61'C; feed pump 10%, N2 flow: 2800 l/min. The starting material was prepared by mixing two solutions A and B immediately before spray drying

Solution A: 20 g of water was used to dissolve 0.5 g of human pancreatic DNase I (Calbiochem. San Diego, CA, USA) and 0.021 g of poloxamer 188 NF grade (BASF. Mount Oliv. NJ, USA)

Solution B: Phospholipid-stabilized fluorocarbon-in-water emulsion was prepared as follows Phospholipid, 0.52 g of EPC - 100 - 3 (Lipoid KG, Ludwigshafen, Germany) was homogenized in 87 g of hot deionized water (T = 50 to 60'C) using one Ultra-Turrax stirrer (model T-25) at 8000 rpm for 2 to 5 minutes (T = 60 - 70* C). 13 g of perflubron (Atochem, Paris) was added dropwise while stirring. After that, the emulsion was mixed for at least 4 minutes. The resulting coarse emulsion was then forced through a high pressure homogenizer (Avestin, Ottawa, Canada) at 18000 psi (about 1240 bar) in 5 passes.

Solutions A and B were combined and fed into the spray dryer under the above conditions. A free-flowing, pale yellow powder was collected from the cyclone. The hollow porous particles of DNase I had a mean aerodynamic diameter of 1.29 +_1.40 microns, as determined by a time-of-flight analytical procedure (Aerosizer, Amherst Process instruments, Amherst, MA, USA). SEM analysis proved that the particles are both hollow and porous. The average density of the powder was determined to be less than 0.1 g/cm^.

The preceding example further demonstrates the excellent compatibility of the present invention with respect to various bioactive agents. This means that, in addition to relatively small, hard compounds such as steroids, gentle molecules such as proteins and genetic material can be processed.

XIV -

Preparation of perforated polymer ink particles by spray drying In the following hypothetical example, finely divided porous spherical resin particles, which may contain colors such as pigments, stains, etc., the following formulation was prepared according to these instructions:

Formulation:

Butadiene

7,5 g

co-monomer

styrene

2,5 g

- •' -

Water

18,0 g

carrier

fatty acid soap

0,5 g

emulsifier

n-added mercaptan

0,05 g

modifier

sodium persulfate

0,03 g

initiator

coal soot

0,50 g

pigment

The reaction was allowed to run for 8 hours at 50°C and then completed by spray drying the emulsion using a high pressure liquid chromatography (HPLC) pump. The emulsion was pumped through one tube

length 200 with an inner diameter of 0.03 inches (about 5000 mm x 0.8 mm) of stainless steel into an atomizer of the same material of a portable spray dryer (Niro Atomize, Copenhagen, Denmark), equipped with two nozzles (inner diameter of 0.01 " = about 0.25 mm) with the following adjustments

Hot air flow 39.5 CFM (about 28 l/min)

Inlet air temperature 180'C

Outlet air temperature: 90'C

Nitrogen flow through the atomizer 45 l/min at 1800 psi (about 124 bar)

Feed liquid flow: 33 ml/min.

It will be clear that unreacted monomers serve as propellants, creating pearlized microstructures. The described formulation and conditions give a free-flowing powder of polymer particles in the range of 0.1 - 100 microns, which can be used in ink formulations. In accordance with the instructions given here, the microparticles have the advantage of containing the pigment directly in the polymer matrix. The process enables the production of particles of different sizes by changing the components and spray drying conditions, whereby the diameter of the pigment particles is largely dictated by the diameter of the polymer resin brushes.

XV

Test with the Andersen impactor to determine the performance of MDI and DPI devices

The MDI and DPI devices were tested using generally accepted pharmaceutical procedures. The procedure used was in accordance with the United States Pharmacopeial Procedure (USP), (Pharmaceutical Reviews 1996, 22; 3065-3098), which is incorporated herein by reference. After 5 thrown batches, 20 MDI batches were loaded into one Andersen impactor. The number of batches used to determine the DPI formulations was determined by the drug concentration and ranged from 10 to 20 device activations.

Extraction procedure. Extraction from all the plates, the introduction part and the actuators were done in closed vials with 10 ml each of odgoavarajubeg solvent. The filter was installed, but not tested, because the polyacrylic binder would interfere with the analysis. The mass balance and the tendency of the particle size distribution indicated negligible sedimentation in the filter. Methanol was used for the extraction of beclomethasone dipropionate. Deionized water was used for albuterol sulfate and cromolyn sodium. For MDI albuterol, 0.5 ml of 1N sodium hydroxide was added to the plate extract, which was used to convert albuterol to the phenolate form.

Quantification procedure. All drugs were quantified by absorption spectroscopy (Beckman DUB40 spectrophotometer) against an external standard curve with an extraction curve as a blank. Beclomethasone dipropionate was quantified by measuring the absorbance of the plate extract at 238 nm.

MDI albuterol was quantified by measuring the absorbance of the extract at 243 nm, while cromolyn sodium was quantified by using the absorption peak at 326 nm.

Calculation procedure. For each MDI, the masses of the drug in the base (component -31, to the actuator (-21). introductory

part (-1) and plates (0 - 7) were quantified as described above. Grades -3 and -2 were not quantified at DPI, as this device was a prototype. The main interest was determining the aerodynamic properties of the powder leaving the device. Fine particle dose and Fine-particle fraction were calculated according to the USP procedure, referenced above. Throat deposition was defined as the mass of drug found in the inlet and on plates 0 and 1. Mass mean aerodynamic diameter (MMAD) and geometric standard diameter were determined. by creating a cumulative experimental function with a normal logarithmic distribution, using a two-parameter insertion procedure. The results of these tests will be given in the following examples.

XVI

Preparation of metered dose inhalers containing hollow porous particles

Previously measured amounts of hollow porous particles prepared in Examples 1, X, XI and XII were placed in 10 ml aluminum vessels, and dried in a vacuum oven in a stream of nitrogen for 3-4 hours at 40' C. The amount of filled powder in the vessels was determined by the amount of the drug required for a certain therapeutic effect. After that, the vessels were sealed using a DF31/50act 50 valve (Valois of America, Greenwich, CT, USA) and filled with HFA-134a (DuPont, Wilmington, DE, USA) propellant, higher pressure through the neck. The amount of propellant can be determined by measuring the vessel before and after filling.

XVII

Effect of powder porosity on MDI performance

In order to examine the effect of powder porosity on the stability of suspensions and aerodynamic diameters, MDI devices were prepared as in Example XVI with various preforms peforized microstructure containing gentamicin formulations, as described in Example I MDI with a content of 0.48% by weight. spray-dried powders in HFA 134a were studied. As noted in Example I, spray-dried powders exhibit varying porosity. Formulations are filled in transparent glass vials for visual observation.

A strong dependence of suspension stability and mean measured aerodynamic diameter was observed as a function of PFC/PC ratio and/or porosity. Mean measured aerodynamic diameter (VMAD) decreased and suspension stability increased with increasing porosity. Powders that appeared solid and smooth by SEM and TEM had the worst suspension stability and the highest mean MDI aerodynamic diameter. filled with highly porous and hollow perforated microstructures showed the highest resistance to densification and the smallest aerodynamic diameters. The measured VMAD values for the dry powders produced according to Example I are shown in Table III immediately below

XVIII

Comparison of thickening rates of cromolyn sodium formulations

A comparison of the densification rates of commercial Intal formulations (Rhone-Poulenc, France) and hollow porous particles spray-dried in HFA-134a, according to Example XII (ie, see Fig. 3) is shown in Figs. 4A to 4D. In each of these images, taken at 0 s., 30 s., 80 s. and 2 hours after churning, the commercial formulations are on the left and the perforated microstructures according to this invention are on the right. While the commercial Intal formulations show densification within 30 seconds of the start of shaking, almost no densification was observed in the spray-dried particles even after 2 hours. Moreover, there was very little densification in the perforated microstructures after 4 hours (not shown). This example clearly illustrates the density balance that can be achieved when hollow porous particles are filled with suspension media (ie creating homodispersion).

XIX

Anderson cascade impactor test results for cromolyn sodium formulations

The results of cascade impactor tests with a commercially available product (Intal(R), Rhone-Poulenc, France) and an analogous spray-dried hollow porous powder in HFA-134a prepared in accordance with Examples XII and XVI are shown below in Table IV. conducted using the protocol shown in Example XV.

MDIs formulated with perforated microstructures were shown to have significantly better aerosol properties compared to lntal(^). At a comparable fines dose, the spray-dried cromolyn formulation had a significantly higher fraction of fines (67%) and significantly reduced throat deposition (8-fold), along with lower MMAD values. It is important to note that efficient delivery using the present invention enabled a dose of fine particles, which was approximately the same as with commercial formulations according to the prior art, although the amount of perforated microstructures administered (300 pg) was only about 1/3 of the dose of lntal(R) -a (800 pg).

XX

Comparison of Andersen cascade impactor results with albuterol sulfate microspheres from DPI and MDI

In vitro aerodynamic properties of albuterol sulfate hollow porous microspheres were determined using a Mark II Cascade Impactor (Andersen Sampler, Atlanta, GA, USA) and an Amherst Aerosizer (Amherst Instruments, Amherst, MA, USA).

DPI Test, Approximately 300 pg of spray-dried microspheres were loaded into a conventional inhaler device. Activation and creation of a dry powder mist was then achieved by activating 50 pl of HFA 134a under pressure through a long inlet tube. Pressurized HFA 134a pushed air through the inlet tube towards the sample chamber and then aerosolized a dry powder mist into the air. One actuation is discharged from the device into the impactor. Between two activations, a load interval of 30 s was left. Results were quantified as described in Example XV.

Examination of MDI. A preparation of albuterol sulfatase MDI microspheres was prepared as in Example XVI and one run was discharged into the sample chamber of an Aerosizer for particle size analysis. 20 actuations are discharged from the device into the impactor. A time interval of 30 s is left between each activation. Again, the results were quantified as described in Example XV.

A comparison of the particle size analysis results of pure albuterol sulfate powder and albuterol sulfate powder expelled from a single DPI or MDI is given in Table V below. The albuterol sulfate powder from the DPI was indistinguishable from the pure powder, indicating that little or no aggregation during activation. On the other hand, some aggregation was observed when working with MDI, which was shown in the larger aerodynamic diameter of the particles ejected from the device.

Similar results were observed when comparing the two dosage forms using the Andersen Cascade lmpactor (SI.5) Spray-dried albuterol sulfate powder from DPI had better deep penetration into the patient's lungs and minimized throat deposition compared to that from MDI. MDI formulations had a fine particle fraction (FPF) of 79% and a fine particle dose (FPD) of 77 p.g per 1 actuation, while DPI had an FPF of 87% and an FFD of 100 pcj/actuation

SI.5 and the example above demonstrate the excellent aerodynamic properties and flowability of the DPI spray-dried powders described herein. Indeed, one of the primary advantages of this invention is the ability to produce small, aerodynamically light particles that aerosolize easily and possess excellent inhalability. These powders possess unique properties that allow them to be delivered efficiently and effectively from either an MDI or DPI device. This principle is further illustrated by the following example.

XXI

Comparison of Anderson Cascade Impactor Results for Beclomethasone Diproionate Microspheres from DPI and MDI Devices

In vitro aerodynamic properties of hollow porous microspheres of declomethasone diproionate (BDP). prepared according to Example XI obtained using an Anderson Mark II Cascade sampler (Anderson Sampler. Atlanta, GA, USA) and an Amherst Aerosizer (Amherst instruments, Amherst, MA. USA).

DPI testing. Approximately 300 pg of spray-dried microspheres were loaded into a proprietary inhaler. Activation and subsequent misting of the dry powder was achieved by activating 50 pl of HFA 134a through a long inlet tube. HFA 134a under pressure forced air through the inlet pipe towards

chamber with the sample and then it is aerosolized into a mist of dry powder and expelled into the air. The dry powder mist was then introduced into the cascade impactor by an air stream through the test device. One actuation was discharged into the sample chamber of the Aerosizer for particle size analysis. 20 actuations are discharged from the device into the impactor. After each activation, a time interval of 30 s was left.

F^tBbaaatgMMDI beclomethasone dipropionate (BDP) in the form of microspheres was prepared as in Example XVI. One actuation was discharged into the sample chamber of the Aerosizer for particle size analysis. 20 activations were discharged from the device into the impactor. A time interval of 30 s was left between each activation.

The results of a comparison of the particle size of pure BDP powder and the same ejected from a DPI or MDI device are shown in Table VI immediately below.

As in Example XX, the BDP powder ejected from the DPI was indistinguishable from the clean powder and indicated that there was little or no aggregation during activation. On the other hand, some aggregation was observed when ejecting from the MDI, confirmed by the larger aerodynamic diameters of the particles ejected from the device.

The spray-dried BDP powder released from the DPI had improved deep lung penetration and minimal throat deposition compared to MDI. The MDI formulation had an FPF of 87% and FPD to g&RtKirana.

The preceding example serves to illustrate the inherent versatility of the present invention as a drug delivery base capable of effectively containing one or more pharmaceutical agents and delivering them efficiently from various types of delivery devices (here MDIs and DPIs) now in use in the field of pharmacy. The excellent aerodynamic properties and fluidity of dry powder, shown in the given examples, will be further illustrated in the following example.

XXII

Comparison of Anderson Cascade Impactor Results for Albuterol Sulfate Microspheres and Ventolin Rotacaps from a Single Rotahaler Device

The following procedure was applied to compare the inhalation properties of Ventolin Rotaps (commercial

available formulation) compared to hollow porous microspheres of albuterol phosphate in accordance with the present invention. Both preparations were introduced from one Rotahaler device into an 8-stage Andersen Mark II Cascade Impactor at a flow rate of 80 l/min. The prepared albuterol sulfate microspheres described in Example X with deposition of albuterol sulfate in a cascade impactor were analyzed as described in Example XV. Approximately 300 pg of albuterol sulfate microspheres were manually loaded into empty Ventolin Rotocaps gelatin capsules. The described filling procedure described in the packaging and activation of drug capsules in the Rotohaler device was then carried out. 10 activations were ejected from the device into the impactor. A time interval of 30 s is left between each activation.

The results of a comparison of the cascade impactor analysis with Ventolin Rotocaps and albuterol sulfate hollow porous microspheres ejected from the Rotohaler device are shown in Table VII immediately below

The hollow porous albuterol sulfate powder ejected from the Rotohaler device had a significantly higher fraction of fine particles and a lower MMAD compared to Ventolin Rotacaps. In this regard, commercially available Ventolin Rotocaps formulations had a fine particle fraction (FPF) of 20% and a fine particle dose (FDP) of 15 pg/actuation, while albuterol sulfate hollow porous microspheres had an FPF of 83% and an FPD of 80 pg/actuation. .

The preceding example illustrates the excellent aerodynamic properties and flowability of spray-dried powders from the Rotohaler. What's more, this example shows that fine powders can be administered efficiently without carrier particles. ,

XXIII '

Misting of porous particle structures with phospholipid and chromolinate content in perfluorooctylethane using MicroMist - fogger

40 mg of lipid-based microspheres with a content of 50% by weight. cromolyn sodium (as in Example XII) was dispersed in 10 ml of perfluorooctylethane (PFOE) by shaking, creating a suspension. This suspension was misted until the hydrocarbon liquid was exhausted or evaporated using a MicroMist (de Vilbiss) disposable fogger using a PulmoAide air compressor (de Vilbiss). As described above in Example XV, an Anderson Cascade impactor was used to measure the resulting particle size distribution. In more detail, the cromolyn sodium content was measured by ultraviolet (UV) adsorption at 326 nm. The fraction of fine particles is the ratio of particles precipitated in degrees 2 to 7 in relation

to those, precipitated in all stages of the impactor. The mass of fine particles is the weight of material deposited in stages 2 to 7. The fraction for penetrating deep into the lungs is the ratio of particles deposited in stages 5 to 7 of the impactor (which corresponds to those deposited in the alveoli to those deposited in all other stages) Mass deposited deep in in the lungs, the weight of the material is deposited in grades 5 to 7. Table VIII immediately below shows the sum of these results

XXIV

Fogging of porous particle structures with phospholipids and cromolyn sodium in perfluorooctylethane using a Raindrop fogger

A quantity of lipid-based microspheres containing 50% cromolyn sodium, as in Example XII, weighing 40 mg, was dispersed in 10 ml of perfluorooctylethane (PDFE) by shaking, thereby creating an emulsion. The suspension was fogged until the fluorocarbon liquid was consumed or evaporated using a Raindrop-Fog-Disposable Impactor (Nellcor Puritan Bennet, attached to a PulmoAid - compressor (de Vilbiss). An Anderson Cascade Impactor was used to measure the resulting particle size distribution as described in Examples XV and XXIII Table IX immediately below summarizes the results.

Table IX

XXV

Clouding of an aqueous solution of cromolyn sodium

The bag of a plastic unit dose inhalation solution containing 20 mg cromolyn sodium in 2 ml purified water (Dey Laboratories) was misted with a disposable MicroMist nebulizer (de Vilbiss) using a PulmoAid air compressor (de Vilbiss). The cromolyn sodium solution was nebulized for 30 minutes. An Anderson Cascade impactor was used to measure the resulting size and distribution of nebulized particles, using the procedure described above in Example XV. Table X immediately below provides a summary of the results

In view of the present results, it will be clear that the formulations nebulized from the fluorocarbon suspensions of Examples XXIII and XXIV give a higher % deposition deep into the lung, compared to the aqueous solutions. Such high deposition values deep into the lungs are particularly desirable when administering agents into the patient's systemic circulation.

It will further be apparent to those skilled in the art that this invention may be embodied in other specific forms in the spirit of its basic idea. In this respect, the foregoing descriptions of the present invention disclose only exemplary embodiments thereof, and it is to be understood that other variations are contemplated and considered within the scope of the present invention. Therefore, the present invention is not limited to the particular embodiments described in detail herein. Moreover, reference should be made to the attached Claims, indicative of the scope and explanation of this invention.

Claims (61)

1. Use of a bioactive agent in the production of a drug for pulmonary administration, specified time. that the drug consists of a large number of perforated microstructures that are aerosolized using an inhalation device in order to obtain an aerosolized drug containing the mentioned bioactive agent. Wherein the said aerosolized drug is in a form for administration to at least one part of the nasal or pulmonary airways of the patient who needs it. 2. Use of Claims 1. specified time. that the mentioned inhalation device consists of a metered dose inhaler. dry powder inhalers or nebulizers. 3. Use of Claim 1, specified time. which are the mentioned perforated microstructures in the form of dry powder. 4. The use of Claim 1, the specified time, which is the mentioned perforated microstructures dispersed in a non-aqueous suspension medium. 5. Use of any of Claims 1 to 4. it is significant that the mentioned pearlized microstructures contain some surfactant. 6. Use of Claim 5, it is indicated that the mentioned surfactant is selected from the group consisting of phospholipids, non-ionic detergents, non-ionic block polymers. of ionic surlactans. biocompatible fluorinated surlactans and their combinations. 7. Use of requirements 5 or 6, specified times. which said surfactant is a phospholipid 8. Use of Claim 7, specified time. said phospholipid is selected from the group consisting of dilauroylphosphate dilcholine, dioleoylphosphate dilcholine, dipalmitoylphosphate dilcholine, disteroylphosphate dilcholine, dibehenoylphosphatylcholine, diarachidoylphosphate dilcholine and combinations thereof. 9. Use of any of claims 1 to 8, specified times. which is the mean aerodynamic diameter of perforated microstructures between 0.5 and 5 f.lm. 10. Use of any one of Claims 1 to 9, provided that the aforementioned perforated microstructures have a bulk density of less than about 0.5 g/cm3 11. Use of any of Claims 1 to 1O. a significant time. that the mentioned pearlized microstructures have a mean geometric diameter smaller than about 5 f.lm. 12. The use of any one of Claims 1 to 11, in which the said bioactive agent is selected from the group consisting of antiallergic agents. bronchodilators. pulmonary surfactants, antibiotics, leukotriene inhibitors. or antagonists, antihistamines, anti-inflammatory agents. antineoplastics, anticholinergics, anesthetics, antituberculin, cardiovascular agents, enzymes. steroid viral vectors. antidote agents, proteins, peptides and their combinations. 68 13. Procedure for forming pearlescent microstructure. important time. which consists of the following steps: creating a liquid starting material containing an active agent: atomizing said liquid starting material to create dispersed liquid droplets drying said liquid droplets under certain predetermined conditions to form perforated microstructures containing said active agent. and collection of the mentioned periorized microstructures. 14. Procedure from Claim 13, specified time. that the mentioned starting material contains some propellant. 15. Procedure from requirement 14, significant time. that said propellant coagulates non-fluorinated oil. 16. Procedure according to Request 14. significant time. that the mentioned propellant creates a fluorinated compound. 17. Procedure according to Request 16. significant time. that the mentioned propellant has a boiling point higher than 60°C. 18. Procedure according to any of Claims 13 to 17. significant time. which mentions that the starting material contains a colloidal system. 19. Procedure according to any of Claims 13 to 18. significant time. that the mentioned starting material creates a surfactant. 20. Procedure according to Request 19. significant time. that said surfactant is selected from the group consisting of phospholipids. nonionic detergents. of nonionic block polymers. of ionic surfactants. biocompatibilities of fluorinated surfactants and their combinations. 21. Procedure according to request 19 or 20. n a n a c e n t i m e . which is the mentioned surfactant phospholipid. 22. Procedure according to Request 21. significant time. wherein said phospholipid is selected from the group consisting of dilauroylphosphatedylcholine. dioleylphosphatedylcholine. dipalmitoylphosphatedylcholine. distaroylphosphatedylcholine. dibe henoylphosphatedylcholine, diarachidoylphosphatedylcholine and their combinations. 23. Procedure according to any of Claims 13 to 22. significant time. which are mentioned- gathered perforated microstructures of hollow porous microspheres. 24. Procedure according to any of Claims 13 to 23. significant time. that the mean aerodynamic diameter of the collected puerforized microstructures ranges between 0.5 and 5.11m 25. Procedure according to any of Claims 13 to 24. significant time. that the mentioned perforated microstructures have a mean geometric diameter smaller than about 5 11m. 26. 69 Procedure according to any of Claims 13 to 2 5. the specified agent contains one bioactive agent, as mentioned active 27. Procedure according to Request 26. n a n c e n t i m e . The bioactive agent mentioned is selected from the group consisting of antiallergic agents, txonhodilators, pulmonary surfactants. analgesics. antibiotics, leukotriene inhibitors and antagonists, antihistamines, anti-inflammatory agents, antineoplastics, anticholinergics, anesthetics, anthtuberculin, contrast agents. of cardiovascular compounds, enzymes. steroids. genetic material, viral vectors, antisense compounds, proteins, peptides and their combinations. 28. Procedure according to any of Claims 13 to 27. It is important to note that the aforementioned step of atimization is performed using a sprayer. 29. Perforated microstructure, significant times. which is formed according to any of Claims 1 3 to 28. 30. The procedure for increasing the dispersibility of the powder, the specified time, which contains the steps of: creating a liquid starting material with an active agent content: and spray drying said liquid starting material in order to produce a powder of perforated microparticles with a volume density of less than 0.5 glcm3, whereby said powder shows reduced van der Waals forces in comparison with relatively non-porous powders of the same composition. 31. The procedure from Claim 30, it is important that the mentioned liquid starting material contains one bioactive agent. 32. The procedure from Claim 31, it is important that the mentioned propellant contains one non-fluorinated oil. 33. Procedure from Claim 31, specified time. that said propellant contains one fluorinated compound. 34. The procedure from Claim 33, characterized in that the mentioned fluorinated compound has a boiling point higher than 60'. 35. Procedure according to any of Claims 30 to 34. important points • that the mentioned starting material contains surfactant. 36. The procedure from Claim 35, characterized in that the mentioned surfactant is selected from the group consisting of phospholipids, non-ionic detergents. nonionic block polymer a. ionic surfactants, biocompatible fluorinated surfactants and their combinations. 37. The procedure from Claim 35 or 36, the main point being that the mentioned surfactant is phospholipid. 38. The procedure according to Claim 37, it is important that the mentioned phospholipid is selected from group 70 consisting of: dilauroylphosphatidylcholine, diol and phosphatidylcholine. dipalmitoilf osfatidylcholine, dister oilf ospha thydylcholine. dibehenoylphosphatidylcholine, diarachidoylphosphatidylcholine, and their combinations. 39. Procedure according to any of Claims 30 to 38. n a _significant time. the aforementioned perforated microstructures consist of hollow porous microspheres. 40. Procedure. according to any of Claims 30 to 38. it is significant that the mentioned active agent contains one bioactive agent. 41. Procedure according to request 40. it is significant that the mentioned bioactive agent is selected from the group consisting of antiallergic agents, bronchodilators, pulmonary surfactants. analgesics. antibiotics. leukotriene inhibitors and antagonists, antihistamines, anti-inflammatory agents, antineoplastics, anticholinergics, anesthetics, anti-tuberculin, contrast agents, cardiovascular agents, enzymes. ster oid. genetic material, viral vectors. antidote agents, proteins, peptides and their combinations. 42. Powder made of perforated microstructure. significant time. which is formed according to any of Claims 30 to 41. 43. Powder. increased dispersivity, significant time. which consists of a large number of perforated microstructures with a bulk density of less than 0.5 g/cm3, whereby the powder of said perforated microstructure contains one active agent. 44. The powder from Claim 43, specified time. that the mentioned powder consists of hollow porous microspheres. 45. Powder from Claim 43 or 44. significant time. which is the mean aerodynamic diameter of the mentioned perforated microstructures between 0.5 and 5 f.lm 46. Powder according to any one of Claims 43 to 46. significant time. that the mentioned pearlized microstructures have a mean geometric diameter of less than about 5 µm. 47. Powder. according to any one of Claims 43 to 46, n a n c e n t i m e . that the aforementioned peforized microstructures will form a surfactant. 48. Powder. according to Request 47. It is important that the mentioned surfactant is selected from the group consisting of phospholipids, non-ionic detergents, and non-ionic block copolymers. of ionic surfactants. of biocompatible fluorinated surlactans and their combinations. 49. Powder from Claims 47 or 48, n a c e n t i m e . - that said surfactant is a phospholipid. 50. Powder from Request 49. significant time. said phospholipid is selected from the group consisting of dilauroylphosphatidylcholine. dioleylphosphatidylcholine, dipalmitoylphosphatidylcholine, disteroylphosphatidylcholine. dibehenoyl phosphatidylcholine. diarachidoylphosphatidylcholine. and their combinations. 51. Powder according to any one of Claims 43 to 50, n e c h e n t i m e . which is the mentioned active agent 71 one bioactive agent. 52. Powder according to claim 51, n a n a c e n t i m e . that the mentioned bioactive agent is selected from the group consisting of antiallergic agents, bronchodilators. pulmonary surfactants. analgesics, antibiotics. inhibit o ra and antagonist of leukotrienes. antihistamines, anti-inflammatory agents, antineoplastics, anticholinergics. anesthetics, anti-tuberculin. contrast agents. cardiovascular agents, enzymes. steroids. genetic material, viral vectors, countermeasures. proteins, peptides and their combinations 53. Inhalation system for pulmonary administration of a bioactive agent to the patient. significant time. which consists of: an inhalation device with a tank and a burst in that tank. wherein said powder consists of a large number of perforated microstructures with a volume density of less than about 0.5 g/cm3 and wherein said powder of perforated microstructures contains one bioactive agent, whereby said inhalation device enables aerosol administration of said powder in at least one part of the patient's nasal or pulmonary airways. who needs it. 54. The system from Claim 53, characterized in that the mentioned inhalation device consists of a dry powder inhaler, a metered dose inhaler or a fogger. 55. System from Claim 53, significant. that the mentioned perforated microstructures are dispersed in a non-aqueous suspension medium. 56. System from Request 55. significant time. that said non-aqueous suspension medium contains one fluorinated compound. 57. The system according to any one of Claims 54 to 56, characterized in that said perforated microstructures contain a surfactant. 58. System from requirement 57. significant time. that said surfactant is selected from the group consisting of phospholipids, nonionic detergents, nonionic block copolymers, ionic surfactants, biocompatible fluorinated surfactants and their combinations. 59. System from Claim 57 or 58, characterized in that said surfactant is a phospholipid. 60. The system according to any one of Claims 54 to 59. significant time. that the mentioned bioactive agent is selected from the group consisting of antiallergic agents, bronchodilators, pulmonary surlactans. analgesics. antibiotics. leukotriene inhibitors and antagonists. antihistamines, anti-inflammatory agents. antineoplastic, anticholinergic. anesthetics, anti-tuberculin, contrast agents, cardiovascular agents, enzymes. steroids, genetic material, viral vectors. antidote agents, proteins. peptides and their combinations. 61. Procedure for pulmonary administration of one or more bioactive agents. significant time. which 72 consists of the following steps: creation of a powder consisting of a large number of pearlized microstructures with a volume density of about 0.5 g/cm3, whereby the aforementioned perforated microstructures are now a bioactive agent: aerosolization of the aforementioned powder from perforated microparticles to obtain an aerosolized drug; and INHALE THERAPEUTIC SYSTEMS INC. Agents, administering a therapeutically effective amount of said aerosolized drug to at least one portion of the nasal or pulmonary airways of a patient in need thereof.