HK1060523B - Oral dosage self-emulsifying formulations of pyranone protease inhibitors - Google Patents

Description

Oral self-emulsifying pyranone protease inhibitor formulations

This application is a continuation-in-part application of prior provisional application USSN 244434 filed on 31/10/2000.

Technical Field

The present invention relates to unique oral formulations of 5, 6-dihydro-4-hydroxy-2-pyrone compounds. In particular, the present invention relates to substantially alcohol and propylene glycol free microemulsified formulations of 5, 6-dihydro-4-hydroxy-2-pyrone protease inhibitors that significantly improve bioavailability and stability at room temperature.

Background

Since the identification of acquired immunodeficiency syndrome (AIDS) in the early 80 s, AIDS and its devastating consequences have been the subject of intense coverage on news reports and scientific literature papers. It is widely believed that this syndrome results from an infection with a retrovirus commonly referred to as the Human Immunodeficiency Virus (HIV). Since its identification, AIDS has progressed from a medical novelty that only infects a small population to a problem that infects a large proportion of the population for more than two decades. Millions of people in the united states alone are considered seropositive for HIV.

The first drug approved for the treatment of HIV-infected patients at 3/20 in 1987 was Azidothymidine (AZT). Recently, zidovudine (or AZT) has been approved for the treatment of AIDS patients with recent episodes of Pneumocystis carinii pneumonia or patients infected with virus and having an absolute CD4 lymphocyte count in the peripheral blood of less than 200/mm³The patient of (1). AZT is believed to act by inhibiting viral reverse transcriptase, an enzyme required for human immunodeficiency virus replication.

After a short period of time, the number of approved antiretroviral drugs has increased from one drug of general activity to twelve with real efficacy. Approved antiretroviral drugs fall into three categories: nucleoside analog reverse transcriptase inhibitors; non-nucleoside analog reverse transcriptase inhibitors; and protease inhibitors. Highly effective antiretroviral therapy (commonly referred to as "HAART") almost always involves protease inhibitors in combination with one or more other classes of drugs. Protease inhibitors have been shown to have potent antiretroviral activity as a phylum.

The first protease inhibitor was approved by the U.S. Food and Drug Administration (FDA) in 1995, and it can be said that this drug revolutionized the treatment of HIV infection. Protease inhibitors are characterized by converting what was once considered uniformly incurable disease into a more benign chronic infectious disease. Five protease inhibitors have been currently approved by the U.S. food and drug administration: amprenavir, indinavir, nelfinavir, ritonavir and saquinavir.

Retroviral proteases are enzymes essential for the maturation of viral particles to their infectious stage. Inhibition of the protease or its absence or non-functionality results in the inability of the virus to replicate efficiently, thereby preventing the production of infectious viral particles. For example, the retroviral protease "gag-protease", which is also one of the smallest enzymes (comprising only 99 amino acids and demonstrating homology to aspartyl proteases such as pepsin and renin), is responsible for the correct proteolytic cleavage of the precursor protein made from the genomic region encoding the "group-specific antigen" ("gag"). It is believed that the protease is encoded by the "pol" region of the viral genome, which also includes regions of reverse transcriptase and integrase. The Gag-proteases preferentially cleave the major core protein p24 of HIV-1 and HIV-2 at the N-terminus of proline residues, for example in the bivalent residues Phe-pro, Leu-pro or Tyr-pro. During the cleavage, the structural proteins of the viral core are released. In summary, gag-protease is necessary to process HIV-fusion polypeptide precursors to allow maturation of gag and gag/pol fusion polypeptides, including capsid and replicase (e.g., reverse transcriptase, integrase).

Many highly potent HIV protease inhibitors have been described in the literature. Protease inhibitors refer to a group of compounds that inhibit aspartic proteases of viral origin and are useful in the prevention or treatment of viral infections caused by retroviruses, such as HIV, in mammals. It can be said that protease inhibitors have revolutionized the treatment of HIV infection, since combination therapy with such compounds in combination with inhibitors of viral DNA polymerase reverse transcriptase has led to the apparent complete inhibition of viral replication. Resistance to protease inhibitors is thought to be caused by mutations in the protease coding domain of retroviruses. Unfortunately, most of these mutations promote cross-resistance for the five protease inhibitors currently approved in the United states (Swanstrom et al, Pharmacol. Ther., 86 (2): 145-170 (2000)).

HIV protease inhibitors may be peptidomimetic or non-peptidomimetic in nature.

Compounds of reduced peptidic or non-peptidic nature generally have improved pharmacokinetic profiles over their peptide analogs. Peptide HIV protease inhibitors often have low bioavailability and rapid excretion due to rapid gastrointestinal breakdown. In general, non-peptidic compounds have better bioavailability and do not excrete rapidly.

Existing non-peptide protease inhibitors are characterized by being hydrophobic and/or lipophilic in nature. Conventional solid and liquid pharmaceutical formulations comprising these inhibitors cannot be absorbed in a satisfactory manner due to this solubility characteristic, i.e. poor water solubility. Among the various factors that can affect the bioavailability of a drug when administered orally, including water solubility, drug absorption through the gastrointestinal tract, dose concentration, and first pass effect, water solubility is generally considered to be one of the most important factors. Poorly water soluble compounds often have unstable or incomplete absorption, thus producing less than desirable reactions.

5, 6-dihydro-4-hydroxy-2-pyrone compounds are well known as potent inhibitors of retroviral proteases. Thus, they are useful for the inhibition of human immunodeficiency virus (HIV-1 or HIV-2 strain and/or human T cell leukemia virus (HTLV-I or HTLV-II)) and for the prevention of AIDS. However, such protease inhibitors typically have very poor water solubility. For example, the free acid form of the 5, 6-dihydro-4-hydroxy-2-pyrone sulfonamide compound tipranavir has very low water solubility, about 10ug/ml at a pH of about 6-7. Approximately 15 capsules of disodium salt (4.5 grams) per dose must be taken twice daily to achieve therapeutic drug levels. Attempts to find other solid state salts of such compounds with significantly improved water solubility have not been successful. Salt formulations of these compounds are generally prone to precipitation of the parent free acid in the gastrointestinal tract.

Many attempts have been made to improve the bioavailability of non-peptide protease inhibitors in general, and 5, 6-dihydro-4-hydroxy-2-pyrone peptidase inhibitors in particular. There is a recognized need in the art to develop improved oral forms of HIV protease inhibitors that will have suitable oral bioavailability, stability and side effects. Because of the low solubility of many non-peptide protease inhibitors in free and salt form, many attempts have been made to deliver drugs in so-called "emulsified" dosage forms, i.e., dosage forms comprising a drug, a hydrophilic phase and a lipophilic phase. This strategy may be similar and in view of the strategy adopted in the solubilization of cyclic poly-N-methylated undecamide polypeptides of the cyclosporin class, by mixing them in an emulsion comprising a lipophilic phase of fatty acid triglycerides of medium chain length, a hydrophilic surfactant such as Cremophor RH40 (BASF corporation) and propylene glycol (see european patent EP0539319B1), significantly improving their bioavailability. So-called SEDDS (self emulsifying drug delivery system) formulations employ high liquid and surfactant content in order to adequately disperse the drug upon mixing with an aqueous medium.

International application PCT/US97/20794(WO 98/22106) to Abbott laboratories discloses an oral liquid SEDDS pharmaceutical composition that is said to improve the oral bioavailability of HIV protease inhibitors, including certain protease inhibitors of 5, 6-dihydro-4-hydroxy-2-pyrone. Such compositions include pharmaceutically acceptable emulsified compositions comprising a long chain fatty acid composition, or a mixture of a pharmaceutically acceptable long chain fatty acid with a pharmaceutically acceptable alcohol and optionally a surfactant (e.g., cremophor el, BASF). Preferred compositions comprise ethanol or propylene glycol or both. It is said that the preferred long chain fatty acid composition comprises about 40 to 70% long chain fatty acid by total weight of the solution, about 5 to 10% surfactant by total weight of the solution, and about 1 to 15% ethanol or propylene glycol by total weight of the solution. The beagle dog and human studies showed that the mean bioavailability of at least five HIV protease inhibitors was improved over the free base and ditosylate salts of the HIV protease inhibitor ritonavir.

U.S. patent No. 5484801 issued to Abbott laboratories relates to a pharmaceutical composition of an HIV protease inhibiting compound in a pharmaceutically acceptable organic solvent, the composition having: (a) a solvent selected from the group consisting of propylene glycol and polyethylene glycol (in an amount of about 10 to 50% by weight of the total solution) or (b) a solvent selected from the group consisting of polyoxyethylene glycerol, triricinoleate, polyethylene glycol 40 hydrogenated castor oil, fractionated coconut oil, polyoxyethylene sorbitan monoceate and 2- (2-ethoxyethoxy) ethanol (in an amount of about 5 to 35% by weight of the total solution) or (c) a mixture thereof, and ethanol or propylene glycol (in an amount of about 5 to 45% by weight of the total solution).

International application PCT/EP96/02431(WO 96/39142) and US 6008228 to Hoffmann-La Roche AG describe a pharmaceutical composition which is said to also improve the bioavailability of protease inhibitors. The composition comprises a pharmaceutically acceptable carrier comprising a fatty acid glyceride of single medium chain length, preferably comprising a single C₆～C₁₂And has an acid number of less than or equal to about 2.5. It is said that it is preferred that the ratio of mono-medium chain length fatty acid glycerides to protease inhibitors is at least about 1.5.

International patent No. PCT/US95/0529 to UpJohn discloses the use of 5, 6-dihydro-4-hydroxy-2-pyrone compounds to treat retroviral infections, but does not recognize the inherent bioavailability difficulties of such compounds. The patent teaches that such compounds can be prepared in the form of the disodium salt in conventional compressed tablets (mixing the compound with conventional ingredients such as talc, magnesium stearate, etc.), or in conventional syrups and elixirs.

International patent applications PCT/US98/14816(WO99/06043), PCT/US98/14817(WO99/06044), PCT/US98/14818(WO99/06024), and US 6121313 to Pharmacia & UpJohn, Inc. teach self-emulsifying dosage forms containing a basic active compound which are said to enhance the oral bioavailability of such compounds. The compositions disclosed therein comprise mixtures of diglycerides and monoglycerides or basic amines with one or more pharmaceutically acceptable surfactants and solvents, which are said to enhance absolute oral bioavailability. The preferred surfactant is Cremophor EL or Cremophor RH40 and the preferred solvent is propylene glycol or a mixture of propylene glycol and 95% (v/v) ethanol.

With respect to 5, 6-dihydro-4-hydroxy-2-pyrone protease inhibitors, PCT/US98/14816 states that the solvents used may comprise polypropylene glycol, propylene glycol, polyethylene glycol, glycerol, ethanol, triacetin, dimethyl isosorbide, ethylene glycol furfural (glycofurol), propylene carbonate, water, dimethylacetamide or mixtures thereof. The preferred solvent for such compounds is said to be propylene glycol or a mixture of propylene glycol and 95% (v/v) ethanol. In the mixture of propylene glycol and ethanol, the amount of propylene glycol is said to be about 50-95%. Surfactants which can be used with such compounds are disclosed TO be nonionic surfactants including Polyoxyl 40 hydrogenated castor oil (e.g. Cremophor RH40), Polyoxyl 35 castor oil (e.g. Cremophor EL or Cremophor EL-P), polysorbates, Solutol HS-15, Tagat TO, Peglicol 6-oleate, polyoxyethylene stearates, saturated polyglycolyzed glycerides or poloxamers (poloxamers). For such emulsified compositions, it is specified that the preferred surfactant is Cremophor RH40 or Cremophor EL. It is disclosed that when amines are employed in the composition, such amines should include lower alkylamines such as ethanolamine, diethanolamine, triethanolamine, dimethylaminoethanol, tris (hydroxymethyl) aminomethane or ethylenediamine; quaternary amines such as choline hydroxide; and basic amino acids such as arginine, lysine or guanidine. Preferred lower alkylamines are dimethylaminoethanol or tris (hydroxymethyl) aminomethane. When a mixture of diglycerides and monoglycerides is included in the composition, such mixture preferably includes diglycerides and monoglycerides in a weight ratio of about 9: 1 to 6: 4, wherein the diglycerides and monoglycerides are mono-or di-unsaturated fatty acid esters of glycerol having a chain length of 16 to 22 carbon atoms. A typical pyrone composition of this invention is said to comprise 1-40% by weight of a drug, 5-35% by weight of a mixture of diglycerides and monoglycerides, and about 10-50% by weight of a pharmaceutically acceptable solvent. The basic amine may optionally be added in an amount of about 0.1 to 10% by weight of the total composition.

Among the known 5, 6-dihydro-4-hydroxy-2-pyrones having protease inhibitory activity, 5, 6-dihydro-4-hydroxy-2-pyrone sulfonamides are particularly found to have high protease inhibitory activity (Turner et al, JMed. chem., 41 (3): 3467-3476 (1998)). In particular, one of them has excellent potency against the viral aspartic proteases of various HIV type 1 laboratory strains and clinical isolates, including those strains and clinical isolates resistant to the reverse transcriptase inhibitors zidovudine and delavirdine, a non-peptidic compound HIV protease inhibitor, tipranavir, (6R) -3- [ (1R) -1- [3- ({ [ 5- (trifluoromethyl) (2-pyridyl) ] sulfonyl } amino) phenyl ] propyl } -4-hydroxy-6- (2-phenylethyl) -6-propyl-5, 6-dihydro-2H-pyran-2-one (also disclosed in the nomenclature of U-140690 and PUN-140690):

formula IV

Tipranavir (formula IV) (m.w.: 602.98) is known to have high activity against HIV-1 variants that are resistant to peptidomimetics (peptidomimetics) protease inhibitors (Poppe et al, anti. agents chemie, 41 (5): 1058-1063 (1997)). In vitro testing of this drug demonstrated Ki values of about 8pM (i.e., higher enzyme inhibition) and IC90 values of about 100nM in antiviral cell cultures (Turuer et al, J.Med.chem., 41 (18): 3467-. It has a LogP of about 6.1, and a pKAs of 6.2-8.2. It is hypothesized that tipranavir binds to the active site of proteases in a soft material, making it a better protease inhibitor than existing protease inhibitors (Larder et al, IAPAC 3rd International Workshop on HIV Drug Resistance and treatment strategies, June 23-26 (1999)).

In an in vitro culture study of 134 clinical isolates with a wide variety of resistances to existing peptidomimetic protease inhibitors, it was determined that 105 viruses were more than ten-fold resistant to three or four protease inhibitors, and that on average 6.1 mutations in the protease gene were 90% sensitive to tipranavir (Larder et al, AIDS, 14 (13): 1943-. In another study, tipranavir has been shown to retain sustained antiviral activity against isolates resistant to the three protease inhibitors indinavir, ritonavir and nelfinavir currently available (Rusconi et al, antibiotic. Agents Chemother., 44 (5): 1328-1332(2000) similar sustained activity on saquinavir resistance has also been reported (Larder et al, IAPAC 3)^rd International Workshop on HIV Drug Resistance andTreatment Strategies，June 23-26(1999))。

It has been found that 5, 6-dihydro-4-hydroxy-2-pyrone protease inhibitors, particularly 5, 6-dihydro-4-hydroxy-2-pyrone sulfonamide inhibitors such as tipranavir, are particularly difficult to formulate into oral dosage forms. A great deal of effort has been devoted to formulating such drugs into oral products with a modest bioavailability. For example, Tipranavir forms highly hygroscopic salts, reducing the stability of the drug. After many years of effort, the innovations of tipranavir identified the best oral formulation, and currently an emulsified formulation comprising the drug, a lipophilic phase comprising diglycerides and monoglycerides, a surfactant, a basic amine, and an aqueous phase comprising propylene glycol and an alcohol, all packaged in a soft gelatin capsule was prepared. While such formulations provide good oral bioavailability of the drug, they also have a number of disadvantages, including: the tendency of the capsules to soften and stick to each other over time; the bioavailability is significantly reduced after sealing in soft gelatin capsules; the formulations have to be refrigerated before use to prevent changes in the composition in the capsule; and require complex manufacturing processes that must be employed to produce consistent capsule fills due to the volatile nature of ethanol.

There is therefore a need for improved oral dosage forms of protease inhibitors in general, and in particular of 5, 6-dihydro-4-hydroxy-2-pyrone protease inhibitors, especially of 5, 6-dihydro-4-hydroxy-2-pyrone sulfonamide protease inhibitors such as tipranavir.

Summary of The Invention

Oral formulations of improved pyranone protease inhibitors and methods of making such formulations are disclosed. The formulation improves the solubility, stability and/or bioavailability of the pyranone drug substance, reduces the number of cumbersome manufacturing steps in the filling process, and allows the capsules to be stored at room temperature. Of particular advantage, the present invention provides oral formulations of tipranavir.

"pyrone" compounds refer to compounds of formula I below:

formula I

Wherein R is¹Is H-; r₂Is C₃-C₅Alkyl, phenyl- ((CH)₂)₂-，het-SO₂NH-((CH₂)₂-, cyclopropyl ((CH)₂)₂-, F-phenyl- ((CH)₂)₂-，het-SO₂NH-phenyl-, or F₃C-((CH₂)₂-; or R₁And R₂Bonding to a double bond; r₃Is R₄-(CH₂)_n-CH(R₅)-，H₃C-[O((CH₂)₂]₂-CH₂-，C₃-C₅Alkyl, phenyl- ((CH)₂)₂-，het-SO₂NH-((CH₂)₂-，(HOCH₂)₃C-NH-C(O)-NH-(CH₂)₃-，(HO₂C)(H₂N)CH-((CH₂)₂-C(O)-NH-(CH₂)₃-, piperazin-1-yl-C (O) -NH- (CH)₂)₃，HO₃S((CH₂)₂-N(CH₃)-C(O)-(CH₂)₆-C(O)-NH-(CH₂)₃-, cyclopropyl- ((CH₂)₂-, F-phenyl- ((CH)₂)₂-，het-SO₂NH-phenyl, or F₃C-((CH₂)₂-; n is 0, 1 or 2; r₄Is phenyl, het, cyclopropyl, H₃C-[O((CH₂)₂]₂-，het-SO₂NH-，Br-，N₃-, or HO₃S((CH₂)₂-N(CH₃)-C(O)(CH₂)₆-C(O)-NH-；R₅is-CH₂-CH₃or-CH₂-a cyclopropyl group; r₆Is cyclopropyl, CH₃-CH₂-, or tert-butyl; r₇is-NR₈SO₂-het，-NR₈SO₂-phenyl, optionally substituted with R₉substituted-CH₂-SO₂-phenyl, optionally substituted with R₉Substituted, or-CH₂-SO₂-het；R₈is-H, or-CH₃；R₉is-CN, -F, -OH, or-NO₂(ii) a Wherein het is a 5-, 6-or 7-membered saturated or unsaturated ring containing 1 to 3 heteroatoms selected from nitrogen, oxygen and sulfur; and includes bicyclic groups in which any of the above heterocycles are fused to a benzene ring or other heterocycle, optionally substituted with-CH₃，-CN，-OH，-C(O)OC₂H₅，-CF₃，-NH₂or-C (O) -NH₂Substituted; or a pharmaceutically acceptable salt thereof; and compounds of the following formula II and formula III:

formula II formula III

Wherein R is₁₀Is H-, CH₃O-, or CH₃O-[((CH₂)₂O]₃-；R₁₁Is cyclopropyl, or-CH₂-CH(CH₃)₂；R₁₂is-NR₁₄SO₂-phenyl, optionally substituted with R₁₅Substituted, -NR₁₄SO₂-het，-CH₂-SO₂-phenyl, optionally substituted with R₁₅Substituted, or-CH₂-SO₂-het；R₁₃is-H' - ((CH)₂)₂-CH₃，-CH₂Cyclopropyl, or-CH₂-a phenyl group; r₁₄is-H, or-CH₃；R₁₅is-CN, -F, -CH₃-COOH, or-OH; wherein het is a 5-, 6-or 7-membered saturated or unsaturated ring containing 1 to 3 heteroatoms selected from nitrogen, oxygen and sulfur; and includes bicyclic groups in which any of the above heterocycles are fused to a benzene ring or other heterocycle; optionally substituted by one or two-CH₃，-CN，C(O)OC₂H₅or-OH; or a pharmaceutically acceptable salt thereof.

It has been found that it is difficult to use ethanol and propylene glycol in current oral formulations of pyranone protease inhibitors. As discussed above with respect to the prior art, while other solvents have been proposed for forming microemulsions of pyranone protease inhibitor compounds, it has been thought that the incorporation of ethanol and propylene glycol in such microemulsion formulations is preferred and results in an optimal formulation. It has been found that while these solvents work well to form emulsions of pyranone protease inhibitors, they can migrate into the gel shell surrounding such microemulsion formulations, thereby causing changes in the phase composition of the formulation, the solubility of the drug, and adversely affecting the structural integrity of the capsule. As a result, the capsules become sticky at room temperature, and therefore require refrigeration conditions.

New self-emulsifying formulations have been found which do not require the inclusion of ethanol or propylene glycol in the formulation. Since these formulations are particularly stable at room temperature, the oral pharmaceutical formulations of pyranone protease inhibitors can be greatly improved. Such formulations enable the patient to access the pyranone protease inhibitor and release its activity through a facility that is within the reach of the patient to provide sufficient refrigeration. Moreover, such formulations have a more consistent bioavailability than current formulations using large amounts of ethanol or propylene glycol in the formulation.

The present invention relates to formulations that are substantially free of substantial amounts of ethanol and propylene glycol (preferably less than about 0.5%, more preferably less than about 0.1% ethanol or propylene glycol or both) which provide more stable formulations of pyranone protease inhibitors, particularly sulfonamide pyranone protease inhibitors such as tipranavir. Such formulations comprise from about 1 to about 40% by weight of the total composition of a pyranone protease inhibitor, from about 1 to about 35% by weight of the total composition of a lipophilic phase, preferably a mixture of diglycerides and monoglycerides, from about 20 to about 60% by weight of the total composition of a surfactant, from about 10 to about 40% by weight of the total composition of a polyethylene glycol having an average molecular weight of greater than about 300 but less than 600, and from about 0.1 to about 10% by weight of the total composition of one or more basic amines.

Surprisingly, the present inventors have determined that polyethylene glycols having an average molecular weight greater than about 300 but less than 600 (preferably about 400) can be used in self-emulsifying microemulsion formulations to solubilize pyranone protease inhibitors, particularly sulfonamide pyranone protease inhibitors, without the need for alcohol or propylene glycol, and that such polymers do not migrate into or adversely affect gelatin capsules.

There are many alternative possibilities for formulating pyranone protease inhibitors without alcohol or propylene glycol, and many microemulsion phase studies employ different combinations of materials in order to identify workable formulations with clinically effective bioavailability. After many attempts have failed, it has been found that certain polyethylene glycols having suitable molecular weights can effectively replace propylene glycol and/or ethanol used in conventional formulations of pyranone protease inhibitors. Such replacement is relatively inexpensive and effective, and has been unexpectedly found to significantly improve bioavailability and stability.

In a preferred embodiment, a pharmaceutical composition is disclosed that is substantially free of alcohol and propylene glycol, comprising, as an active agent, a pyrone compound of formula I, II, or III, one or more pharmaceutically acceptable surfactants, and a polyethylene glycol having an average molecular weight greater than 300 but less than 600. The medicament preferably comprises a compound of formula I, II or III in an amount of about 1 to 40% by weight of the total composition, and further comprises a basic amine in an amount of about 0.1 to 10% by weight of the total composition. The basic amine is preferably a lower alkylamine, a basic amino acid or choline hydroxide, preferably the lower alkylamine is selected from ethanolamine, diethanolamine, triethanolamine, ethylenediamine, dimethylaminoethanol or tris (hydroxymethyl) aminomethane. The pharmaceutical composition may further comprise a mixture of monoglycerides and diglycerides in an amount of about 5 to 35% by weight of the total composition, preferably comprising Capmul MCM. The compositions are particularly effective with tipranavir (the compound of formula IV). Also preferred is an amount of polyethylene glycol of about 10 to 40% by weight of the total composition. More preferably, the polyethylene glycol has an average molecular weight of about 400. Preferably, the pharmaceutically acceptable surfactant is present in an amount of about 20 TO 60% by weight of the total composition and is selected from Polyoxy 40 hydrogenated castor oil, Polyoxy 35 castor oil, Solutol HS-15, Tagat TO, Peglicol 6-oleate, polyoxyethylene stearate, poloxamer, polysorbate, or saturated polyglycolyzed glycerides. Preferably, the Polyoxyyl 35 castor oil is Cremophor EL or Cremophor EL-P.

In another embodiment of the present invention, a pharmaceutical composition is disclosed that is substantially free of alcohol and propylene glycol, comprising tipranavir (formula IV) in an amount of about 1-40% by weight of the total composition; a lipophilic phase in an amount of about 5 to 35% by weight of the total composition; polyethylene glycol in an amount of about 10 to 40% by weight of the total composition and having an average molecular weight greater than about 300 but less than about 600; a pharmaceutically acceptable surfactant in an amount of about 20-60% by weight of the total composition, preferably selected from polyoxyl (polyoxyl) castor oil, polyoxyethylene glycerol triricinoleate, and saturated polyglycolized caprylic-capric glycerides; and a basic amine in an amount of about 0.1 to 10% by weight of the total composition, preferably the basic amine is selected from the group consisting of lower alkyl amines, basic amino acids or choline hydroxide. Preferably, the lipophilic phase comprises a mixture of medium chain length monoglycerides and diglycerides such as Capmul MCM.

In yet another embodiment of the present invention, a pharmaceutical composition substantially free of alcohol and propylene glycol is disclosed, comprising: tipranavir (formula IV) in an amount of about 1-40% by weight of the total composition; an oleophilic phase in an amount of about 5 to 35% by weight of the total composition, preferably the oleophilic phase is selected from the group consisting of Capmul MCM, Labrafil M-1944CS, Miglyol-812, and combinations thereof; polyethylene glycol in an amount of about 10 to 40% by weight of the total composition and having an average molecular weight greater than about 300 but less than about 600; and a pharmaceutically acceptable surfactant in an amount of about 20-60% by weight of the total composition, preferably the surfactant is selected from polyoxyl castor oil, polyoxyethylene glycerol triricinoleate and saturated polyglycolized caprylic-capric glyceride. Preferably, such compositions further comprise a basic amine selected from the group consisting of a lower alkyl amine, a basic amino acid, or choline hydroxide in an amount of about 0.1 to about 10% by weight of the total composition.

Drawings

The foregoing and further objects, features and advantages of the invention will be more completely understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which:

FIG. 1 is a phase diagram of a microemulsion comprising a surfactant Cremophor EL, a hydrophilic phase propylene glycol, and a lipophilic phase Capmul MCM at different concentration ratios from one another.

FIG. 2 is a phase diagram of a microemulsion comprising surfactant Cremophor EL, hydrophilic phase PEG400, and lipophilic phase Capmul MCM at different concentration ratios from each other.

FIG. 3 is a phase diagram of a microemulsion comprising the surfactant Cremophor EL, the hydrophilic phase PEG400, and the lipophilic phase Labrafil M-1944CS at different concentration ratios from each other.

FIG. 4 is a phase diagram of a microemulsion comprising a surfactant Labrasol, a hydrophilic phase PEG400, and a lipophilic phase Capmul MCM at different concentration ratios from one another.

Fig. 5 is a graph of the in vitro dissolution of tipranavir in the two microemulsion formulations set forth in tables 1 and 2.

Fig. 6 is a graph of the in vitro dissolution profiles of tipranavir in a self-emulsifying formulation as described in table 2 encapsulated in a hydrophilic soft gelatin sleeve at different temperatures and/or relative humidities after 3 months storage.

Fig. 7 is a graph of the in vitro dissolution profile of tipranavir encapsulated in a lipophilic soft gelatin sleeve in a self-emulsifying formulation as described in table 2 at different temperatures and/or relative humidities after 3 months storage.

Detailed description of the invention

The present invention overcomes many of the difficulties associated with the required low stability and formulation characteristics of pyranone protease inhibitors. The present invention provides novel formulations of pyranone protease inhibitors that significantly improve the solubility and bioavailability of oral forms of such protease inhibitors.

In any oral formulation, solubility properties are important factors. However, formulations must also be considered economically viable methods to produce a wide variety of physicochemically stable and effective oral formulations. Furthermore, any of the components of the formulation must have satisfactory processability. The present invention provides a method for economically preparing and handling oral dosage forms of pyranone protease inhibitors having improved bioavailability and stable physicochemical properties.

The compounds of formulae I, II, III and IV of the present application are disclosed and claimed in International patent application PCT/US95/05219 and may be prepared according to the procedures described in International patent application WO 95/30670, the disclosure of which is incorporated herein by reference in its entirety. By "pyranone protease inhibitor" is meant any compound defined by formulas I, II, III and IV that inhibits the retroviral protease.

The self-emulsifying formulation of the present invention refers to a composition comprising a pyrone protease inhibitor, a lipophilic phase, a hydrophilic phase, preferably a hydrophilic phase with polyethylene glycol, one or more pharmaceutically acceptable surfactants and a basic amine in an amount of 0.1 to 10% by weight of the total composition. "self-emulsifying formulation" means a condensed composition that forms an emulsion or microemulsion when mixed with sufficient aqueous medium. The emulsions or microemulsions produced by the present invention are solutions comprising a hydrophilic phase and a lipophilic phase. Microemulsions are also characterized by their thermodynamic stability and small average droplet size (typically less than about 0.15 microns).

"basic amine" means a lower alkylamine such as ethanolamine, diethanolamine, triethanolamine, dimethylaminoethanol, tris (hydroxymethyl) aminomethane or ethylenediamine; quaternary amines such as choline hydroxide; basic amino acids such as arginine, lysine or guanidine. Preferred lower alkylamines are dimethylaminoethanol or tris (hydroxymethyl) aminomethane.

The term "pharmaceutically acceptable surfactant" refers to nonionic surfactants including Polyoxyl 40 hydrogenated castor oil, especially sold under the trade name Cremophor RH 40; polyoxyl 35 castor oil, especially sold under the trade name Cremophor EL or Cremophor EL-P (BASF corporation); a polysorbate; solutol HS-15; tagat TO; peglicol 6-oleate; polyoxyethylene stearate; saturated polyglycolized caprylic-capric acid glyceride sold under the tradename Labrasol (Gattefosse, Westwood NJ); saturated polyglycolyzed glycerides; or poloxamers, of all the commercially available surfactants Cremophor EL is preferred.

"lipophilic component" or "oleophilic phase" is meant to include many components having lipid-like properties and high solubility in lipid compounds, including caprylic/capric triglyceride, especially the trans-esterification product of olive oil and PEG (or unsaturated pegylated glyceride obtained by partial alcoholysis of olive oil comprising glycerides and PEG esters), sold under the trade name Labrafil M1944 CS (Gattefosse, Westwood, NJ), sold under the trade name Captex 300(Abitec, Columbus OH); mono-and di-glycerides of caprylic and capric acid in glycerol, especially under the trade name Capmul MCM (Abitec, Columbus OH); and fractionated oils comprising caprylic-capric triglyceride (such as coconut oil), especially under the trade name Miglyol 812.

The term "monoglyceride" refers to a fatty acid ester of glycerol, which has the formula HOCH₂-CH(OH)-CH₂(O₂CR) or HOCH₂-CH(O₂CR)-CH₂OH, wherein R is a mono-or di-saturated alkyl group having 8 to 10 carbon atoms. The term "diglyceride" refers to a fatty acid ester of glycerol having the formula HOCH₂-CH(O₂CR)-CH₂(O₂CR) -or (RCO)₂)CH₂-CH(OH)-CH₂(O₂CR) wherein R is a mono-or di-saturated alkyl group having 8 to 10 carbon atoms. Mixtures of diglycerides and monoglycerides may be prepared by mixing the individual diglycerides and monoglycerides in the appropriate relative proportions and/or by partial hydrolysis of triglycerides, or by transesterification of triglycerides, diglycerides and glycerol.

Polyethylene glycol or PEG refers to a compound having the general formula HOCH₂(CH₂)CH₂)mCH₂A polymer of OH, wherein m represents the average number of oxyethylene groups. The numbers after PEG indicate the average molecular weight of the polymer. Commercially, PEG is available from Union Carbide, Inc. as well as other sources.

With respect to the compositions of formula IV (tipranavir), it is particularly preferred that the compositions of the present invention provide a PEG-based self-emulsifying vehicle comprising about 10-40% PEG400 (more preferably about 15-30% PEG400), about 20-60% Cremophor EL (more preferably about 35-50% Cremophor EL), about 5-35% Capmul MCM (more preferably about 7-15% Capmul MCM), and about 0.1-10% basic amine.

It has been noted that self-emulsifying formulations of conventional pyranone protease inhibitors comprising propylene glycol and/or an alcohol, which are stored in soft gelatin capsules for a period of time, have a slow and less complete dispersibility in aqueous media, with a solubility reduction of about 40% compared to freshly prepared formulations. It is also noted that the bioavailability of these drugs in humans is lower than that of bulk solutions of similar formulations filled into gelatin capsules just prior to administration. It is hypothesized that this effect may be due to migration of the solvent in the formulation into the capsule.

Preliminary studies were conducted to modify the gelatin formulation of the capsule to prevent migration of solvent from the emulsified formulation into the capsule. This attempt was not successful. A study was then conducted to determine whether the propylene glycol and alcohol solvents used in conventional formulations could be completely or partially replaced by another solvent.

A microemulsion phase diagram was constructed for systems containing various lipophilic phases, hydrophilic phases, and surfactants. It has been determined after extensive research that many pyranone protease formulations, including tipranavir, are soluble in polyethylene glycols within a defined average molecular weight range and can be used to replace propylene glycol and ethanol in conventional microemulsion formulations of this drug.

FIG. 1 is a phase diagram of a microemulsion comprising Cremophor EL surfactant, Capmul MCM oleophilic phase (as in conventional pyrone protease inhibitor formulations) and propylene glycol hydrophilic phase at different concentration ratios from each other. It can be seen that this composition provides a stable microemulsion over a wide range of component concentrations. However, since propylene glycol is soluble in the capsules surrounding the formulation, the point in the phase diagram at which the formulation is defined can vary significantly as more propylene glycol is removed from the emulsion over time. Thus, the solubility of the drug in the formulation can change dramatically over time.

FIG. 2 is a phase diagram of a microemulsion including Cremophor EL surfactant, Capmul MCM lipophilic phase, PEG-400 hydrophilic phase at different concentration ratios relative to each other. The phase diagram using PEG-400 (instead of propylene glycol as in fig. 1) is characterized in that it is similar to that which can be seen in fig. 1.

The effect of lipophilic phase on the phase stability of the microemulsion of figure 2 was determined by studies that show that the preferred lipophilic phase comprises a mixture of medium chain length mono-and di-glycerides, such as those found in CapmulMCM. FIG. 3 is a phase diagram of a microemulsion comprising the surfactant Cremophor EL, the hydrophilic phase PEG400, and the lipophilic phase Labrafil M-1944CS at different concentration ratios from each other. Labrafil-M-1944 is a trans-esterification product of olive oil and PEG, i.e. unsaturated polyglycolyzed glycerides obtained by partial hydrolysis of almond oil, comprising glycerides and PEG esters. The stability of the microemulsion was found to be more limited over a wide range of component concentrations than the microemulsion system of fig. 2 using Capmul MCM oleophilic phase. Capmul MCM is a mixture of mono-and di-glycerides of caprylic-capric acid in glycerol.

It was found that by using Labrasol as the surfactant instead of Cremophor EL, the stability of the microemulsion of figure 2 was slightly improved. FIG. 4 is a phase diagram of a microemulsion comprising Labrasol surfactant, PEG400 hydrophilic phase, and Capmul MCM lipophilic phase at different concentrations relative to each other. Although Labrasol provides improved stability, Labrasol has the disadvantage that the safety of long-term oral use in humans has not been demonstrated.

Fig. 5 is a graph of the in vitro dissolution profile of tipranavir from two self-emulsifying formulations listed in tables 1 and 2. The formulation in table 2 differs from the formulation in table 1 in that PEG400 is used instead of ethanol and propylene glycol.

TABLE 1

Components	Measurement of	％w/w
			Tipranavir	250	25
Ethanol	100	10
			Propylene glycol	73	7.3
Cremophor EL	455	45.5
			Capmul MCM	75	7.5
Tromethamine USP	15	1.5
			Pure water USP	30	3.0
Propyl gallate	2	0.2
			Soft gelatin capsule	-	-
Total of	1000	100

TABLE 2

Components	Measurement of	Weight percent of
			Tipranavir	250	25
PEG 400	173	17.3
			Cremophor EL	455	45.5
Capmul MCM	75	7.5
			Tromethamine USP	15	1.5
Pure water USP	30	3.0

Propyl gallate	2	0.2
			Soft gelatin capsule	-	-
Total of	1000	100

It was found that the in vitro dissolution of the formulation of table 2 (using PEG400 instead of the ethanol and propylene glycol hydrophilic solvents used in the formulation of table 1) was almost identical to the formulation of table 1 when it was freshly filled into soft gelatin capsules. On the other hand, in vitro dissolution of the formulation of table 2 was found to be much longer in dissolution time than the dissolution time of the formulation of table 1 when frozen in soft gelatin capsules at 4 ℃ for 14 months.

The self-emulsifying formulation of table 2 was found to provide extremely good stability at room temperature as well as under refrigeration, whether stored in hydrophilic or lipophilic soft gel capsules, which were retained in induction sealed HDPE bottles.

Fig. 6 is a graph of the in vitro dissolution of tipranavir in the formulation of table 2 encapsulated in hydrophilic softgel capsules and stored in induction sealed HDPE bottles after storage for various periods of time at various temperatures and/or relative humidities. All three of the formulations, stored at 5 ℃ for 3 months at 60% relative humidity, at room temperature (25 ℃) for 3 months, and at 30 ℃ and 70% relative humidity for 3 months, all gave almost the same dissolution profile.

Fig. 7 is a graph of the in vitro dissolution of tipranavir from the formulation of table 2 after storage at different temperatures and/or relative humidities for different periods of time. Almost the same pattern can be seen as encapsulated in hydrophilic softgel capsules. The formulation of table 2 encapsulated in lipophilic softgel capsules demonstrated significant stability of the dissolution profile when stored for 3 months in induction sealed HDPE bottles at 5 ℃ or 30 ℃ and 70% relative humidity.

EXAMPLE 1 preparation of PEG-based Tipranavir SEDDS formulation

455mg of Cremophor EL, 75mg of Capmul MCM, and 173mg of PEG400 were added to the mixing vessel and mixed (700rpm) while 2mg of propyl gallate was added as an antioxidant. Mixing was continued until the solution became clear, then 15mg of Tris (hydroxymethyl) aminomethane (Tris) was added (pre-dissolved in water in a ratio of 1: 2). Mixing was continued at high speed (1600rpm) while tipranavir (250mg) was added to the solution. When tipranavir was completely dissolved, mixing was stopped and the solution was allowed to stand for degassing.

EXAMPLE 2 bioavailability of PEG-based self-emulsifying formulation of Tipranavir

In vivo oral bioavailability studies were performed using male beagle dogs. In beagle dogs, the PEG-based tipranavir formulation shown in table 2 was compared to the propylene glycol/ethanol formulation shown in table 1, sealed in a soft gel capsule. The bioavailability of both formulations was found to be statistically the same.

In addition, stability studies were performed on the formulations shown in table 2 in standard soft gelatin capsules. This study shows that the formulations of the present invention provide fewer impurities and are therefore more stable than the formulations in standard soft gelatin capsules shown in table 1. In addition, soft gelatin capsules having the self-emulsifying formulation according to the present invention are not sticky even when stored at 30 ℃ and 70% relative humidity for 6 months.

Although the present invention has been described in terms of preferred embodiments, those skilled in the art will readily appreciate that various changes and/or modifications may be made to the invention without departing from the spirit and scope of the invention as defined by the appended claims. All documents cited herein are incorporated by reference in their entirety.

Claims (18)

1. A pharmaceutical composition having less than 0.5% ethanol and propylene glycol comprising: (a) a pyrone compound of the formula IV,

formula IV or a pharmaceutically acceptable salt thereof;

(b) one or more pharmaceutically acceptable surfactants; and

(c) a polyethylene glycol solvent having an average molecular weight greater than 300 but less than 600.

2. The pharmaceutical composition of claim 1, wherein the amount of the compound of formula IV is 1-40% by weight of the total composition.

3. The pharmaceutical composition of claim 1, further comprising 0.1 to 10% by weight of a basic amine, based on the total weight of the composition.

4. The pharmaceutical composition of claim 3, wherein the basic amine is a lower alkylamine, a basic amino acid, or choline hydroxide, wherein the lower alkylamine is selected from ethanolamine, diethanolamine, triethanolamine, ethylenediamine, dimethylaminoethanol, or tris (hydroxymethyl) aminomethane.

5. The pharmaceutical composition of claim 1, further comprising a mixture of diglycerides and monoglycerides in an amount of 5 to 35% by weight of the total composition.

6. The pharmaceutical composition of claim 5, wherein the mixture of diglycerides and monoglycerides is Capmul MCM.

7. The pharmaceutical composition of claim 5, wherein the diglyceride and monoglyceride are mono-or di-saturated fatty acid esters of glycerol having 8 to 10 carbons in chain length.

8. The pharmaceutical composition of claim 1, wherein the amount of the polyethylene glycol is 10-40% by weight of the total composition.

9. The pharmaceutical composition of claim 8, wherein the polyethylene glycol has an average molecular weight of 400.

10. The pharmaceutical composition of claim 1, wherein the surfactant is present in an amount ranging from 20 to 60% by weight relative to the total weight of the composition.

11. The pharmaceutical composition of claim 10, wherein the surfactant is Polyoxyl 40 hydrogenated castor oil, Polyoxyl 35 castor oil, Solutol HS-15, Tagat TO, Peglicol 6-oleate, polyoxyethylene stearate, poloxamer, polysorbates, or saturated polyglycolyzed glycerides.

12. The pharmaceutical composition of claim 11, wherein said Polyoxyl 35 castor oil is Cremophor EL or Cremophor EL-P.

13. A pharmaceutical composition having less than 0.5% ethanol and propylene glycol comprising:

(a) pyranone compounds of formula IV

The amount of the formula IV is 1-40% of the total weight of the composition;

(b) oleophilic phase in an amount of 5-35% of the total weight of the composition;

(c) polyethylene glycol with the average molecular weight of more than 300 but less than 600, wherein the amount of the polyethylene glycol is 10-40% of the total weight of the composition;

(d) a surfactant selected from polyoxyl castor oil, polyoxyethylene glycerol triricinoleate and saturated polyethylene glycol caprylic capric acid glyceride, wherein the amount of the surfactant is 20-60% of the total weight of the composition; and

(e) a basic amine selected from the group consisting of a lower alkylamine, a basic amino acid or choline hydroxide, wherein the lower alkylamine is selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, ethylenediamine, dimethylaminoethanol or tris (hydroxymethyl) aminomethane in an amount of 0.1 to 10% by weight of the total composition.

14. The pharmaceutical composition of claim 13, wherein the lipophilic phase comprises a mixture of diglycerides and monoglycerides.

15. A pharmaceutical composition having less than 0.5% ethanol and propylene glycol comprising:

(a) pyranone compounds of formula IV

The amount of the formula IV is 1-40% of the total weight of the composition;

(b) an oleophilic phase selected from the group consisting of Capmul MCM, Labrafil M-1944CS, Myglol-812, and combinations thereof in an amount of 5 to 35% of the total weight of the composition;

(c) polyethylene glycol with the average molecular weight of more than 300 but less than 600, wherein the amount of the polyethylene glycol is 10-40% of the total weight of the composition;

(d) and the surfactant is selected from polyoxyl ester castor oil, polyoxyethylene glycerol triricinoleate and saturated polyethylene glycol caprylic capric glyceride, and the amount of the surfactant is 20-60% of the total weight of the composition.

16. The composition of claim 15, further comprising a basic amine selected from the group consisting of a lower alkyl amine, a basic amino acid, or choline hydroxide, wherein the lower alkyl amine is selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, ethylenediamine, dimethylaminoethanol, or tris (hydroxymethyl) aminomethane in an amount of 0.1 to 10% by weight of the total composition.

17. The composition of claim 15 in the form of a liquid that can be encapsulated in a soft elastic capsule.

18. The composition of claim 15 in liquid form that can be encapsulated in a hard gelatin or non-gelatin capsule.