HK1260049B - Method for filling a container with a foamable composition - Google Patents

Description

Method for filling a container with a foaming composition

This application is a divisional application of an invention application filed on April 26, 2013, with Chinese national application number 201380022644.4 and the invention name “Method for filling a foaming composition into a container”.

Technical Field

The present invention relates to a method for preparing a composition comprising gaseous microbubbles. More particularly, the present invention relates to a method for filling the composition into a container. The composition prepared is preferably an ultrasound contrast agent composition that can be provided in a container, wherein the headspace of the container contains the same gas as the gas in the microbubbles, and wherein the gas is different from air.

Background Art

It is well known that ultrasound imaging constitutes a valuable diagnostic tool, for example, for the study of the vascular system, particularly for cardiography, and for the study of tissue microvasculature. A variety of ultrasound contrast agents have been proposed to enhance the acoustic images thus obtained, including suspensions of solid particles, emulsified droplets, gas bubbles, and encapsulated gases and liquids. Generally, the most successful ultrasound contrast agents consist of dispersions of small, intravenously injectable gas bubbles. If properly stabilized, microbubbles can allow for efficient ultrasound visualization of, for example, the vascular system and tissue microvasculature, often at advantageously low doses. Such contrast agents typically include materials that stabilize the gas dispersion, such as emulsifiers, oils, thickeners, or sugars, or stabilize the gas dispersion by generating or encapsulating the gas in various systems, for example, as gas-containing porous microparticles or as encapsulated gaseous microbubbles. The microbubbles include a gas having properties essential to the performance of the ultrasound contrast agent, and various gas-enhancing properties have been discovered, such as microbubble stability and the duration of the echogenic effect. A group of ultrasound contrast agents are prepared and delivered as finished formulations in a container containing a liquid composition of gaseous microbubbles.

In such liquid-liquid combinations containing gaseous microbubbles, the microbubbles typically contain another gas other than air, referred to herein as a dispersed gas, such as a fluorinated gas. To compensate for or prevent the dispersed gas from escaping the microbubbles during storage, the headspace of the container is filled with a headspace gas, typically the same gas used in the microbubbles. Otherwise, over time and as the microbubbles leak, a certain amount of gas within the microbubbles will contain a significant amount of air rather than the desired dispersed gas. Approved liquid ultrasound contrast agents typically include instructions specifying the desired percentage of headspace gas to be used as microbubble gas. Therefore, when preparing contrast agents, the filling process typically includes the following steps: after filling the contrast agent, a purge gas, referred to as the headspace gas, is introduced into the container to expel the air from the headspace, and then the container is capped. However, the applicant has faced a challenge in preparing contrast agents in this manner. It has been found difficult to ensure that absolutely all containers filled with contrast agent contain the desired amount of headspace gas in the headspace. When non-compliance with the instructions is observed, the container, and often the entire batch, must be discarded. In existing preparation methods, a contrast medium composition containing a suspension of microbubbles is pumped from a bulk container and dispensed into vials. Before the stopper and cap are placed into the vial mouth, the air in the vial is evacuated by allowing a heavier-than-air headspace gas to flow into and surround the vial. However, the applicant faces a problem: when the contrast medium is filled into the container, foam and large air-containing gas bubbles may occasionally form due to the Venturi effect, and these large air bubbles continue to exist during the process of feeding the headspace gas into the container. As a result, the desired amount of headspace gas cannot always be achieved in the headspace. Various methods have been tried without success to remove these large air bubbles, such as replacing the air in the bubbles with a dispersed gas. Therefore, there remains a need in the art to provide a method for preparing a container filled with a composition containing gaseous microbubbles in a liquid carrier, wherein the desired amount of headspace gas in the headspace is met.

Summary of the Invention

In response to this need in the art, the present invention provides a method comprising filling a container with a composition comprising gaseous microbubbles, ensuring that, for each filled container, a specification regarding the amount of headspace gas within the container headspace is met. The applicant surprisingly discovered that, rather than replacing air from the headspace of the filled container with headspace gas after the contrast agent is filled into the container, it is advantageous to first introduce the headspace gas into the empty container, thereby replacing the air throughout the container with the headspace gas, before filling the container with the composition.

In a first aspect, the present invention thus provides a method for preparing a container filled with a composition comprising gaseous microbubbles in a liquid carrier, the method comprising the following sequential steps:

a) Using the headspace gas, the air is removed from the container, and then

b) filling the container with the composition.

By using such a filling method, including flushing the empty containers with a headspace gas pre-purge, no air bubbles were generated and it was found that all containers filled with the composition met the specification requirements for the gas in the headspace.

The method further comprises the optional step of closing the container after step b), such as by inserting a stopper into the mouth of the filled container, and/or applying a cap, and/or by crimping a cover onto the stopper and/or cap. The container used in the method of the present invention is a vial, bottle, or bag. The container can be made of glass or plastic, such as transparent or opaque plastic, and can be a rigid or flexible plastic container. The container can be, for example, sized from 3 ml to 50,000 ml, and preferably a vial or bottle of 3 to 500 ml. Most preferably, the container contains one or at least one dose.

When filled into the container, the composition is a finished formulation, i.e., the composition is preferably a dispersion of gaseous microbubbles in a physiologically acceptable aqueous carrier (e.g., water for injection). The composition is ready for injection into a human or animal patient, but may require gentle shaking prior to injection to provide a uniform suspension. The composition can be used for therapeutic or diagnostic purposes, or a combination; and is preferably used as an ultrasound contrast agent for diagnostic purposes. Contrast agents containing gaseous microbubbles are preferred because, if properly stabilized, microbubble dispersions are particularly effective backscatterers of ultrasound due to their low density and compressibility. Ultrasound contrast agents in which the microbubbles contain a carrier with affinity for a biological target are also included.

The gaseous microbubbles used in the methods of the present invention are stabilized by a stabilizer that surrounds the gaseous microbubbles, hindering diffusion of the gas into the surrounding liquid and preventing fusion between the microbubbles. A variety of compositions are encompassed, including, for example, those using gelatin or albumin microbubbles, which initially form in a liquid suspension and encapsulate the gas during solidification. Alternatively, a thick shell can be prepared, such as a sugar or other viscous material, or solid particles or emulsified droplets. Another type of stabilizer encapsulates the gas within the phospholipid layer of the liposome, as described in, for example, US Pat. No. 5,334,381.

Such a stabilizer may be a surfactant or a relatively strong shell material and is, for example, selected from polymers such as polysaccharides, lipids and protein-based materials. The stabilizing material most preferably comprises a phospholipid or a protein-based material, more preferably a heat-denatured biocompatible protein, most preferably human serum albumin.

A biocompatible gas can be used in the microbubbles of the composition and in the first step of the present invention. The headspace gas used in the first step of the present invention is preferably the same as the dispersed gas in the microbubbles. It should be understood that the terms "gas," "dispersed gas," and "headspace gas" include any substance (including mixtures) that is substantially or completely in the form of a gas (including vapor) at the normal body temperature of 37°C. Thus, the gas may include, for example, nitrogen, oxygen, carbon dioxide, hydrogen, nitrous oxide; inert gases such as helium, argon, xenon, or krypton;

Sulfur fluorides, such as sulfur hexafluoride, disulfur decafluoride or trifluoromethyl sulfur pentafluoride;

Selenium hexafluoride;

Optionally halogenated silanes, such as tetramethylsilane;

Low molecular weight hydrocarbons (e.g., containing up to 7 carbon atoms), such as alkanes, such as methane, ethane, propane, butane, or pentane; cycloalkanes, such as cyclobutane or cyclopentane; alkenes, such as propylene or butene; or alkynes, such as acetylene;

ether; ketone; ester;

Halogenated low molecular weight hydrocarbons, e.g., containing up to 7 carbon atoms; or mixtures of any of the foregoing.

Compositions comprising halogenated low molecular weight hydrocarbons are preferred. Advantageously, at least some of the halogen atoms in the halogenated gas are fluorine atoms. Thus, the biocompatible halogenated hydrocarbon gas can be selected from, for example: bromochlorodifluoromethane, chlorodifluoromethane, dichlorodifluoromethane, bromotrifluoromethane, chlorotrifluoromethane, chloropentafluoroethane, dichlorotetrafluoroethane and perfluorocarbons, for example, perfluoroalkanes such as perfluoromethane, perfluoroethane, perfluoropropane, perfluorobutane (e.g., perfluoro-n-butane, optionally mixed with other isomers such as perfluoroisobutane), perfluoropentane, perfluorohexane and perfluoroheptane; perfluoroolefins such as perfluoropropylene, perfluorobutene (e.g., perfluorobut-2-ene) and perfluorobutadiene; perfluoroalkynes such as perfluorobut-2-yne; and perfluorocycloalkanes such as perfluorocyclobutane, perfluoromethylcyclobutane, perfluorodimethylcyclobutane, perfluorotrimethylcyclobutane, perfluorocyclopentane, perfluoromethylcyclopentane, perfluorodimethylcyclopentane, perfluorocyclohexane, perfluoromethylcyclohexane and perfluorocycloheptane. Other halogenated gases include fluorinated (e.g., perfluorinated) ketones such as perfluoroacetone and fluorinated (e.g., perfluorinated) ethers such as perfluoroethyl ether. It can be further advantageous to use the method of the present invention with compositions containing fluorinated gases such as sulfur fluoride or fluorocarbons (e.g., perfluorocarbons), which are known to form particularly stable microbubble suspensions, of which SF ₆ , perfluoropropane and perfluorobutane are preferred, and perfluoropropane is particularly preferred.

More preferably, the method of the present invention is used to prepare a composition comprising microbubbles comprising protein, most preferably albumin, encapsulating a perfluorocarbon gas, most preferably perfluoropropane, also known as octafluoropropane (OFP) or perfluoropropane.

Methods of the present invention are preferred in which the headspace gas is heavier than air. The headspace gas is preferably the same as the dispersed gas so that if or when the dispersed gas leaks from the microbubbles during storage, the headspace gas of the container compensates for this. If the headspace gas is different from the dispersed gas, then over time a certain number of microbubbles will contain the headspace gas instead of the desired dispersed gas. In certain embodiments of the present invention, the headspace gas is alternatively different from the dispersed gas. For example, the gas in the headspace may contain a gas with a lower boiling point than the dispersed gas. This is to avoid condensation of the headspace gas upon cooling, such as when the container is placed in a refrigerator. In this embodiment, the two gases should be similar, such as two different perfluorocarbons with different boiling points. In another embodiment, the dispersed gas is air and the headspace gas is another gas, preferably a heavier gas, such as a fluorinated gas. During storage, a certain number of microbubbles advantageously contain the headspace gas instead of the original air.

The method of the present invention is particularly useful for preparing an aqueous composition of microbubbles, wherein the microbubbles comprise a gas other than air. For purposes of illustration and not limitation, examples of specific ultrasound contrast agents that can be prepared according to the present invention are BR14, MP1950, Optison ^™ , and PESDA, with Optison ^™ being particularly preferred.

The composition used in the method of the present invention can be prepared by different methods to produce a dispersion of gaseous microbubbles, such as by ultrasonic treatment, spray drying or by mechanical mixing, such as using a colloid mill (rotor stator). In one embodiment of the present invention, the method includes a processing step before step a), wherein the composition is prepared by the following method, wherein a solution of the stabilizing material (preferably an aqueous solution of human serum albumin) and the gas to be dispersed are conveyed into a colloid mill, where they are thoroughly mixed. When the uniform dispersion of gaseous microbubbles is prepared, it is sent to a bulk container. The bulk container is, for example, a flexible large bag with a volume of, for example, 10 to 100 L. In step b) of the method of the present invention, the composition is dispensed from the bulk container to the container in which the air in step a) has been replaced by the headspace gas.

Different gas-containing contrast agents may require different amounts (i.e., percentages) of gas in the headspace of the container, depending on, for example, the type of gas contained in the microbubbles, the stabilizing material used, and the ease with which the gas diffuses from the bubbles. Using the method of the present invention, the specification for the amount of dispersed gas in the headspace of each filled container is met. The gas content in the headspace of filled containers is typically measured by gas chromatography, for example, by measuring the concentration of gas in a statistical number of prepared containers. In one embodiment of the present invention, the method of the present invention achieves a gas content of 40-100% by volume of the headspace, such as at least 50%, or preferably at least 60%, such as at least 70%. For the preparation of the ultrasound contrast agent Optison ^™ (which is a preferred embodiment), the specification requirement of at least 60% perfluoropropane in the headspace is met when using the method of the present invention. In containers filled according to the method of the present invention, the headspace is typically about 20-50% of the total volume of the container. When filled with the composition, preferably about 40% of the total volume of the container is headspace. For example, in a 5 mL vial, there is about 3 mL of the composition and about 2 mL of headspace. Furthermore, as described above, when the container is filled with the composition, 40% to 100% of this headspace comprises the headspace gas.

In the method of the present invention, a purge needle connected to a gas cylinder containing the headspace gas is placed within the container, and the empty container is pre-purged with the headspace gas. When purging air, the needle is preferably directed toward the bottom of the container. When the needle is withdrawn from the container, purging is preferably continued to prevent air from entering the container during removal of the purge needle. The empty container is purged with the headspace gas at a rate of, for example, 200 to 800 cc/minute, such as 400 to 600 cc/minute, and preferably approximately 500 cc/minute. The required gas flow rate also depends on the size of the vial used. Because the headspace gas is preferably heavier than air, it will remain within the container during filling of the composition. During filling of the composition, no foam or large bubbles are generated, and at the end of filling, the headspace gas will be located neat at the top of the composition. If bubbles are generated during filling, they contain only the purge gas used and do not reduce the headspace gas content. The step of filling the container with the composition is preferably completed after the step of purging the air from the container, and for example, within 10 seconds, for example, within 5 seconds, after the purging of the air is completed. Preferably, the container is then closed. When using the method of the present invention, filling can be completed quickly and without any problems with foaming, and a large number of packages including containers containing the composition can be produced per day. Using the method of the present invention, approximately 2,000 to 3,000 containers can be filled per hour, depending on several factors, such as the size of the container. If 5 mL vials filled with the composition are produced, then approximately 20 to 50,000 vials can be filled per day, providing an economically viable method.

When using the method of the present invention, the requirement for a certain amount of headspace gas in the headspace is met without any interruption to filling due to foaming, and without any container needing to be discarded. An equilibrium exists between the gas in the headspace and the gas in the microbubbles, and the microbubbles remain stable during storage. After filling and capping, the microbubbles can float, forming a layer on the surface. Resuspension by gentle shaking may be necessary prior to injection into the patient to provide a uniform suspension.

In a second aspect, the present invention provides a container containing a composition prepared according to the method of the first aspect. The composition can be used for therapeutic or diagnostic purposes, or a combination thereof, and is preferably used as an ultrasound contrast agent for diagnostic applications. A variety of imaging techniques can be used in ultrasound applications, including, for example, fundamental and harmonic B-mode imaging and fundamental and harmonic Doppler imaging; if desired, three-dimensional imaging techniques can be used. The contrast agent can also be used in ultrasound imaging methods based on related art.

In another aspect, the present invention provides a device for use in a method of preparing a container filled with a composition comprising microbubbles in a liquid carrier, the device comprising:

i) Pre-purge and flushing device;

ii) a dispensing mechanism for dispensing the composition into the container.

The flushing device preferably includes at least one purge needle connected to a gas tank containing the headspace gas for delivering the headspace gas to the container. For example, the dispensing mechanism includes a conduit connected to a bulk container, wherein a pump pumps the composition from the bulk container through the conduit and dispenses it into the container. The conduit may further be connected to a needle for filling the container. The device preferably further includes a conduit comprising two walls held together by a top, wherein the top comprises one or more openings, preferably at least two openings. The conduit has been found to be useful for reducing the Venturi effect. The purge needle is designed to be inserted into an opening in the top and into the container mouth. Prior to step a) of the method of the present invention, the empty containers are placed on a conveyor belt, which transports them to the conduit of the apparatus, wherein the purge needle is first inserted into the opening in the conduit and into the container mouth, the needle being positioned toward the bottom of the container and the headspace gas being used to expel air from the container. The purge needle is then withdrawn and purge is continued, and subsequently, and preferably within seconds of the end of the purge, the composition is filled into the container using the dispensing mechanism of the device. The conduit of the dispensing mechanism, or alternatively, a filling needle connected to the conduit, is inserted through the other opening of the conduit and into the pre-deaerated container opening. When the pre-deaeration of a batch of containers is completed, the containers are filled and the new batch of containers is purged. Thereafter, the containers are stoppered and capped. This aspect includes the same features as the first aspect, with respect to the choice of gas and stabilizing material.

The invention will now be described with reference to the following non-limiting examples.

DETAILED DESCRIPTION

Example

Example 1: Control Example - Filling of Optison ^™ into Containers with Post-Air Expulsion Vials filled with Optison ^™ were aseptically dispensed, stoppered, capped and crimped using a Groninger filling machine.

The Optison solution was pumped from the bulk container using a peristaltic pump and dispensed into 500 3 mL vials. The pump speed was set to 140 rpm and the pump acceleration was 100%. The vials were then evacuated of air by flowing perfluoropropane (OFP) gas at a flow rate of 300 cc/min through and under the pipes. The Groninger filler then added stoppers, caps, and compression seals.

During a perfluoropropane headspace test for a product batch, 90 samples were tested, and three of them failed the headspace standard of at least 60% headspace. The three failed samples were carried over to the end of the run. To validate the test results, repeat and additional experimental tests were performed. These tests included retesting the three failed headspace samples as well as several passing samples. Based on the test results, both the passing and failed samples were identical to the original test. Using this method, the average perfluoropropane headspace content was 65%.

During the filling of the Optison composition into the vials, large bubbles were observed in the vials. The gas in the large bubbles was not replaced with perfluoropropane during the post-purge process. During storage, the large bubbles collapsed and the gas within them mixed with the headspace gas. Since the gas within the large bubbles was air, the total perfluoropropane gas content in the headspace decreased. After the bubbles collapsed, the perfluoropropane headspace content of the vials containing large bubbles was measured. All of the vials containing large air bubbles did not meet the perfluoropropane headspace specification, with values as low as 40% perfluoropropane in the headspace.

Example 2: Filling of Optison ^™ into containers using the claimed method using pre-exhausted air Vials filled with Optison ^™ were aseptically dispensed, stoppered, capped and crimped using a Groninger filling machine.

Referring to Example 1, the investigation showed that the use of a post-fill purge did not optimize the PFPA headspace content. However, it was determined that a pre-fill PFPA purge of the empty vials prior to filling significantly improved the PFPA headspace content at a purge rate of 500 cc/min.

Five hundred 3 mL vials were pre-deaerated by flowing perfluoropropane gas into and surrounding the empty vials at a flow rate of 500 cc/min. The Optison solution was then pumped from the bulk container and dispensed into the vials using a peristaltic pump. The pump speed was set to 100 rpm with a pump acceleration of 50%. The Groninger filler then added stoppers, caps, and compression seals.

During the process, 90 vials out of 500 were sampled for headspace analysis and inspected for any large bubbles that had formed.

To facilitate the pre-fill purge process, the product filling needle is moved down to the location of the previously used post-fill PFPA purge needle. During the purge process, the purge needle lowers to the bottom of the vial. This positioning of the pre-fill purge needle and product filling needle further optimizes PFPA headspace.

Using this pre-purge method, an average perfluoropropane headspace content of 75% was achieved. Thus, by pre-purging empty vials with 500 cc/min of perfluoropropane gas instead of purging dispensed vials after filling at 300 cc/min, an improvement from an average of 65% to 75% was demonstrated. All vials met the headspace standard of at least 60% headspace. Furthermore, the perfluoropropane headspace was found to have less variability, with the standard deviation reduced from 7.4 to 1.9.

It is important that the purge needle be lowered to the bottom of the vial during the purge process, allowing the air to be purged. If the needle is lowered only to the top of the vial neck, the PFPA will mix with the gas in the vial without purging the air. Using this method, any large bubbles created during the filling process will contain PFPA, not air, and will not reduce the PFPA headspace content.

Method capability calculations were performed using 6σ limits based on the data from the filled vials and concluded that the filling method was stable and that no vials would fail using the recommended pre-purge parameters.

Claims (11)

1. A method for preparing a container filled with an ultrasound contrast agent composition, wherein 40-100% of the headspace volume comprises headspace gas, the composition contains gaseous microbubbles in a liquid carrier, the composition is readily injectable into a patient, wherein the microbubbles comprise a stable material selected from lipids or protein-based materials, the method comprising the following steps in sequence: a) Using the headspace gas, air is expelled from the container, and then... b) Fill the container with the composition, and then seal the container. The headspace gas is a biocompatible halogenated hydrocarbon gas heavier than air, and in step a), the empty container is purged with the headspace gas at a rate of 400-600 cc/min, and the headspace gas used in step a) is the same as the gas in the microbubbles. 2. The method according to claim 1, wherein the protein-based material is a heat-denatured biocompatible protein. 3. The method of claim 1, wherein the protein-based material is human serum albumin. 4. The method according to any one of claims 1-3, wherein the headspace gas is a fluorinated gas. 5. The method according to any one of claims 1-3, wherein the headspace gas is sulfur fluoride or a fluorocarbon. 6. The method according to any one of claims 1-3, wherein the headspace gas is perfluorocarbon. 7. The method according to any one of claims 1-3, wherein the headspace gas is _SF6 , perfluoropropane, and perfluorobutane. 8. The method according to any one of claims 1-3, wherein the headspace gas is perfluoropropane. 9. The method according to any one of claims 1-3, wherein the protein-based material is albumin and the headspace gas is perfluoropropane. 10. The method according to any one of claims 1-3, wherein a purge needle connected to a gas canister containing the headspace gas is placed inside the container, and the empty container is pre-purged using the headspace gas. 11. The method of claim 10, wherein the purge needle is directed toward the bottom of the container when air is vented.