HK1180541B - Stabilized statin formulations - Google Patents

Abstract

The present invention is directed to statin formulations having improved solubility and/or stability and methods for the same.

Description

Stabilized statin formulations

Technical Field

The present invention relates to statin formulations with improved solubility and/or stability and processes for preparing the same.

Background

It has been clear for decades that high blood cholesterol is a major risk factor for Coronary Heart Disease (CHD), and many studies have shown that the risk of CHD events can be reduced by lipid lowering therapies. Prior to 1987, lipid lowering treatments (armamentarium) were essentially limited to diet adjustments to a low saturated fat and cholesterol diet, a bile acid sequestrant (cholestyramine)And colestipol), nicotinic acid (niacin), fibrates, and probucol. Unfortunately, all of these treatments have limited efficacy or tolerance or both. By introducing lovastatinSee U.S. patent No. 4,231,938) -the first inhibitor of HMG-CoA reductase available for prescription in 1987-physicians were able to achieve considerable plasma cholesterol reduction for the first time with very little adverse effect.

HMG CoA reductase inhibitors, commonly known as statins, are divided into two groups: obtained from fermentation and synthesis. In addition to the natural product lovastatin, several semi-synthetic and fully synthetic HMG-CoA reductase inhibitors have been approved for prescription use, including simvastatinSee U.S. Pat. No. 4,444,784), Pravastatin sodium saltSee U.S. Pat. No. 4,346,227), fluvastatin sodium saltSee U.S. Pat. No. 5,354,772), atorvastatin calcium saltSee U.S. Pat. No. 5,273,995) and the sodium salt of cerivastatinSee U.S. Pat. No. 5,177,080). Other HMG-CoA reductase inhibitors are also known in development, such as pitavastatin also known as NK-104 (see PCT International publication No. WO 97/23200); and rosuvastatin also known as ZD-4522See U.S. patent No. 25,260,440 and drug soft Future, 1999, 24(5), page 511-513). The structural formulae of these and additional HMG-CoA reductase inhibitors are described in M.Yalpani, "Cholesterol Power Drugs," Chemistry&Industry, pages 85-89 (1996, 2/5), page 87. The above-mentioned HMG-CoA reductase inhibitors belong to the structural class of compounds comprising a moiety which may be in the form of a 3-hydroxy lactone ring or in the form of the corresponding ring-opened dihydroxy-opening acid (open-acid), and are commonly referred to as "statins".

U.S. patent No. 5,356,896 describes pharmaceutical dosage forms comprising an HMG-CoA reductase inhibitor compound such as fluvastatin sodium that are stabilized against pH related degradation by a basic stabilizing medium capable of administering a pH of at least 8 to an aqueous solution or dispersion of the composition. The' 896 patent states that preferably using a water-based or other solvent-based manufacturing process, it is necessary to bring the drug and the basic medium into intimate contact association, whereby "the drug and basic medium are blended together in the presence of a lesser amount of, for example, water to provide particles of drug and basic substance contained in an intimate mixture". The resulting granules are dried and then blended with fillers and remaining excipients that are set aside to constitute the "outer phase" of the granules to produce compositions suitable for encapsulation, tableting, and the like.

In another embodiment described in the' 896 patent, a solvent-based process is used to facilitate subsequent drying in a fluidized bed, whereby the drug and alkaline medium are wet granulated by known techniques, i.e., blended in the wet state with a quantity of filler material and the resulting granules, combined after drying with any remaining filler and other residues (set-side) such as binders, lubricants, and may thus be tableted, encapsulated, or otherwise formed into dosage forms.

The' 896 patent states that in order to achieve an extended shelf life of the composition, it is important that the "granules prepared by grinding or wet granulation or other water-based process are substantially completely dried, i.e., achieve a loss on drying (l.o.d.) of no greater than 3% and preferably no greater than 2%". The' 896 patent also describes drying by tray drying or conventionally conducted in a fluidized bed, preferably the latter with drying typically conducted at about 50 ℃ inlet temperature and below 50% RH. The' 896 patent further describes an alternative preparation procedure to the above-described milling or wet granulation techniques, wherein the drug substance and the basic stabilizing medium can be co-lyophilized, i.e., freeze-dried, from an aqueous solution as an in situ step of the drug manufacturing process.

Most statins are relatively insoluble and are considered by those skilled in the art to be unstable in solution, and therefore such drugs are manufactured in solid form. However, there are those patients who cannot ingest, digest, or otherwise orally ingest a drug orally, and there is a need for intravenous administration of the drug. The following clinical indications exist: statins by anti-inflammatory and possibly other mechanisms can reduce the incidence of heart attacks, strokes, and other inflammatory mediated conditions.

Summary of The Invention

It is an object of the present invention to provide a stable product comprising statins which can be administered intravenously.

It is a further object of the present invention to provide a solid statin formulation that can be reconstituted in an aqueous solution suitable for injection into a mammal.

It is another object of the present invention to provide lyophilized particles having a statin and a solubilizing or complexing agent.

It is a further object to provide a process for the preparation of lyophilized particles with a statin and a solubilizing or complexing agent.

It is a further object to provide methods of treating human patients with statins using the formulations and methods described herein.

These objects and others are achieved by the present invention which is directed, in part, to a water-insoluble statin complexed in a solution having a pH of about 7 to about 9 with an amount of a pharmaceutically acceptable complexing agent sufficient to provide a solubilized statin concentration of at least about 3.32 mg/ml. The present invention also relates to a pharmaceutical formulation comprising an effective amount of a complexed statin as described above.

In certain embodiments, the solubilized statin concentration is about 1mg/ml to about 25 mg/ml. In certain preferred embodiments, the solubilized statin concentration is about 5mg/ml to about 15 mg/ml. In certain preferred embodiments, the solubilized statin concentration is about 10 mg/ml.

In some embodiments, the statin may be selected from lovastatin, simvastatin, mevastatin, atorvastatin, cerivastatin, and rivastatin.

In some embodiments, the complexing agent is a cyclodextrin. In certain preferred embodiments, the complexing agent is hydroxy-propyl- β -cyclodextrin.

In some embodiments, the complexed statin is lyophilized.

The present invention also relates in part to solid particles comprising a water-insoluble statin, which can be readily dissolved in an aqueous solution suitable for injection into a mammal, said particles being lyophilized particles comprising a pharmaceutically acceptable statin and a sufficient amount of a pharmaceutically acceptable complexing agent.

The present invention also relates in part to lyophilized particles comprising a statin that is insoluble in water and an amount of a complexing agent effective to provide water solubility to the statin and stability to the formulation when reconstituted in an aqueous environment.

In certain embodiments, the lyophilized particles are prepared by first adding the water-insoluble statin to the complexing agent, followed by mixing the combination. In some embodiments, the formulation is subsequently lyophilized to obtain lyophilized particles.

In certain preferred embodiments of the present invention, the lyophilized particles comprising a water-insoluble statin and a complexing agent are stable. By "stable" is meant that substantially no degradation of the lyophilized particles (product) is observed after 1 month of storage at 40 ℃. In a preferred embodiment, the term "stable" with respect to lyophilized particles comprising a water-insoluble statin and a complexing agent means that less than about 0.1% degradation is observed after 1 month of storage at 40 ℃.

In some embodiments of the invention, a pharmaceutically acceptable buffer or alkalizing agent is used to adjust the pH to about 7 to about 9, and suitable alkalizing agents and buffers include, but are not limited to, NaOH, KOH, triethylamine, meglumine, L-arginine, sodium phosphate buffers (trisodium phosphate, disodium phosphate, sodium dihydrogen phosphate, or orthophosphoric acid), sodium bicarbonate, and mixtures of any of the foregoing. In one embodiment of the invention, the lyophilized particles comprise one of the following statins: lovastatin, simvastatin, pravastatin, mevastatin, fluvastatin, atorvastatin, rosuvastatin, cerivastatin, and rivastatin. In certain embodiments, the lyophilized particles may comprise cyclodextrin as a complexing agent, and in certain preferred embodiments, the cyclodextrin is hydroxy-propyl- β -cyclodextrin.

The present invention also relates in part to a process for preparing lyophilized particles comprising a pharmaceutically acceptable statin and a pharmaceutically acceptable complexing agent, wherein the statin is added to a mixture of the complexing agent and a suitable solvent, followed by mixing the combination. In certain embodiments, a pharmaceutically acceptable buffer is then used to adjust the pH to a pH range of about 7 to about 9. The mixture can then be lyophilized to obtain lyophilized particles. The pharmaceutically acceptable statin is preferably water insoluble and may be selected from, for example, the group consisting of: lovastatin, simvastatin, mevastatin, atorvastatin, cerivastatin, and rivastatin. In certain embodiments, the complexing agent is a cyclodextrin.

While in certain preferred embodiments, the present invention contemplates the use of statins that are water insoluble, in other embodiments of the invention, the statins may be water insoluble or water soluble. Examples of suitable water-soluble statins include, but are not limited to, rosuvastatin, fluvastatin and pravastatin.

Thus, in certain embodiments, the present invention relates to stable formulations of soluble statins and methods for preparing the same. In such embodiments, the soluble statin is stabilized via a lyophilization step as described herein.

The present invention also relates to a process for preparing a stable pharmaceutical formulation comprising lyophilized particles of a statin, wherein the statin is complexed with an effective amount of a pharmaceutically acceptable complexing agent in an aqueous solution and the pH is adjusted to about 7 to about 9 prior to lyophilization.

In certain embodiments, the lyophilized particles are reconstituted in an effective amount of a pharmaceutically acceptable solution for injection into a human patient. In certain additional embodiments, the reconstituted lyophilized particles are injected into a human patient.

The invention also relates in part to a method of treatment comprising the steps of: (a) preparing lyophilized particles by adding statin to a mixture of a complexing agent and a suitable solvent and lyophilizing the mixture to obtain lyophilized particles; (b) reconstituting the lyophilized particles in a pharmaceutically acceptable solution for injection; and (c) administering a suitable amount of the solution to a human patient in need of treatment to provide an effective amount of statin. In certain embodiments, the statin is administered in an amount effective to reduce the lipid level of the patient and/or produce a desired (therapeutically effective) anti-inflammatory effect or other therapeutic effect.

In some embodiments, after the statin is added to the mixture of complexing agent and solvent, the mixture is vortexed and sonicated, and the pH of the mixture is adjusted to about 7 to about 9 using a pharmaceutically acceptable buffer.

In certain embodiments, the statin is selected from the group consisting of: lovastatin, simvastatin, pravastatin, mevastatin, fluvastatin, atorvastatin, rosuvastatin, cerivastatin, and rivastatin, and the complexing agent is cyclodextrin.

In certain embodiments of the invention, the complexing agent comprises at least about 13.5% of the formulation.

In certain embodiments of the invention, a solubilized statin concentration of at least about 3.3mg/ml is provided.

As mentioned above, objects of the present invention also include pharmaceutical compositions comprising at least a compound of the invention of formula (I) and non-toxic adjuvants and/or carriers commonly employed in the pharmaceutical field.

Brief Description of Drawings

FIG. 1 shows a linear regression analysis of the minimal amount of HP β -CD required to solubilize AS-Ca.

Detailed Description

The present invention is directed, in part, to pharmaceutical formulations comprising an effective amount of a pharmaceutically acceptable statin complexed with a sufficient amount of a pharmaceutically acceptable complexing agent and processes for preparing the same.

The present invention also relates in part to formulations comprising a water-insoluble statin complexed with a pharmaceutically acceptable complexing agent in an amount sufficient to render the water-insoluble statin soluble in an aqueous environment, the formulations further being lyophilized to provide a stable formulation of the water-insoluble statin that can be dissolved in an aqueous environment.

Suitable water-insoluble statins for use in the present invention include, but are not limited to, lovastatin, simvastatin, mevastatin, atorvastatin, cerivastatin, and rivastatin, pharmaceutically acceptable salts thereof, and pharmaceutically acceptable complexes thereof. The term "water insoluble" as used herein means the USP definition range from minimally soluble to insoluble (solubility no greater than (NMT) 1: 1000). Furthermore, the present invention is intended to cover compositions comprising other HMG-CoA reductase inhibitor compounds of formula I herein, including both red racemates and the constituent isomers thereof (i.e., the 3R, 5S and 3S, 5R isomers, preferably the 3R, 5S isomer).

These compounds are disclosed, for example, in the following commonly issued patents, published patent applications and publications, all of which are hereby incorporated by reference herein: U.S. Pat. No. 4,739,073 and EP- ｃA-114,027(R ═ indolyl and derivatives thereof); EP- ｃA-367,895(R ═ pyrimidinyl and derivatives thereof); U.S. patent No. 5,001,255 (R ═ indenyl and derivatives thereof); U.S. patent No. 4,613,610 (R ═ pyrazolyl and derivatives thereof); us patent No. 4,851,427 (R ═ pyrrolyl and derivatives thereof); U.S. Pat. nos. 4,755,606 and 4,808,607 (R ═ imidazolyl and derivatives thereof); us patent No. 4,751,235 (R ═ indolizinyl and derivatives thereof); U.S. patent No. 4,939,159 (R ═ azaindolyl and derivatives thereof); U.S. patent No. 4,822,799 (R ═ pyrazolopyridinyl and derivatives thereof); us patent No. 4,804,679 (R ═ naphthyl and derivatives thereof); U.S. patent No. 4,876,280 (R ═ cyclohexyl and derivatives thereof); U.S. patent No. 4,829,081 (R ═ thienyl and derivatives thereof); U.S. patent No. 4,927,851 (R ═ furyl and derivatives thereof); U.S. patent No. 4,588,715 (R ═ phenylsilyl and derivatives thereof); and F.G.Kathawa, Medicinal Research reviews, Vol.11 (2), pp.121-146 (1991), and F.G.Kathawa, Atherosporasis Research Review, p.1992, p.6, B73-B85.

Further compounds of formulｃA I are disclosed in e.g. EP- ｃA-304,063(R ═ quinolinyl and derivatives thereof) incorporated herein by reference; EP- ｃA-330,057 and U.S. patent nos. 5,026,708 and 4,868,185 (R ═ pyrimidinyl and derivatives thereof); EP- ｃA-324,347(R ═ pyridazinyl and derivatives thereof); EP- ｃA-300,278(R ═ pyrrolyl or derivatives thereof); and us patent No. 5,013,749 (R ═ imidazolyl and derivatives thereof).

A "complexing agent" is a small molecular weight molecule that can form an inclusion complex and, after a suitable curing time, can solubilize a drug and can impart additional stability to the drug. Thus, for the purposes of the present invention, the term "complexing agent" is intended to include agents that complex and/or solubilize water-insoluble statins. In certain embodiments of the invention, the pharmaceutically acceptable complexing agent is dextrin. Other suitable dextrins include cyclodextrins such as hydroxy-propyl- β -cyclodextrin and sulfobutyl-ether- β -cyclodextrin. Additional cyclodextrins can include alpha-cyclodextrin, beta-cyclodextrin, gamma-cyclodextrin, beta-cyclodextrin ethers comprising one or more hydroxybutyl sulfonate moieties, and cyclodextrins as described in U.S. Pat. No. 6,610,671 or U.S. Pat. No. 6,566,347 (both of which are incorporated by reference).

Additional complexing agents include, but are not limited to, the group consisting of: phenols, phenolates, aromatic acids and esters, carboxylic acids and their salts and esters, inorganic acids and inorganic bases, and amino acids and their esters and salts: methyl paraben, propyl paraben, potassium methylparaben, parabens, ascorbic acid and its derivatives, methyl anthranilate, salicylic acid, acetylsalicylic acid, tocopherol, organic acids, carboxylic acids, aromatic esters, acid salts of amino acids, benzaldehyde, cinnamaldehyde, imidazole, menthol, thiophenol, meta-aminobenzoic acid, anthranilic acid, picolinic acid and its alkyl esters, acyl toluidine, sodium benzoate, sodium metabisulfite, malic acid, erythorbic acid, citric acid, tartaric acid, sodium sulfite, sodium bisulfite, water and fat soluble derivatives of tocopherol, sulfite, bisulfite and sulfurous acid, propyl/gallate, nordihydroguaiaretic acid, phosphoric acid, sorbic acid and benzoic acid, methyl paraben, sodium benzoate, Sodium methyl paraben, p-aminobenzoic acid and esters, sorbic acid and benzoic acid, 2, 6-di-tert-butyl-alpha-dimethylamino-p-cresol, tert-butylhydroquinone, di-tert-amylhydroquinone, di-tert-butylhydroquinone, Butylhydroxytoluene (BHT), Butylhydroxyanisole (BHA), pyrocatechol, pyrogallol, esters, isomeric compounds thereof, pharmaceutically acceptable salts thereof, and mixtures of any of the foregoing.

In certain embodiments of the invention, the complexing agent comprises at least 13.5% of the formulation.

In certain embodiments, the statin and the complexing agent are combined by adding the statin to a mixture of the complexing agent in an aqueous solution. The aqueous solution may be a suitable pharmaceutically acceptable solvent, such as water for injection or Na2HPO4 in water for injection. After complexation of the statin, the pH may be adjusted to a pH above 6.5. In certain embodiments, the pH is adjusted to about 7 to about 9. Suitable agents for adjusting the pH include sodium phosphate buffer (trisodium phosphate (Na)₃PO₄) Or disodium phosphate (Na)₂HPO₄) Orthophosphoric acid, NaOH and L-arginine (L-dArg).

In certain embodiments of the invention, the mixture is mixed by a variety of means, including vortexing and sonication. Mixing may be repeated more than 1 time. It may be desirable to adjust the volume of the solution and/or its pH between each mixing step.

In one embodiment of the invention, the mixture of statin and complexing agent is lyophilized.

The stability of the formulations of the present invention is determined by any suitable method known to those skilled in the art. An example of a suitable method of testing stability is using high performance liquid chromatography or other common analytical techniques.

The daily dose of the active ingredient may be administered as a single dose. The dosage regimen and frequency of administration for the treatment of the mentioned diseases with the compounds of the invention and/or with the pharmaceutical compositions of the invention will be selected in accordance with a variety of factors including, for example, the age, weight, sex and medical condition of the patient and the severity of the disease, pharmacological considerations, the half-life of the drug, and possible concomitant treatment with other drugs. In some cases, dosage levels below or above the aforementioned ranges and/or more frequent may be sufficient, and this will logically be within the judgment of the physician and will depend on the disease state.

When the active ingredient is atorvastatin, the total daily dose may be in an amount of preferably 10 to 80mg, but may be lower or higher as desired. The preferred starting dose of atorvastatin is 10 or 20mg once daily, but can start with 40mg once daily if a large LDL-C reduction is required. The pediatric starting dose of atorvastatin is 10mg once daily and the maximum dose is 20mg once daily. For HMG CoA reductase inhibitors other than atorvastatin, it would be within the understanding of those skilled in the art to calculate the conversion dose based on the preferred dose of atorvastatin. Furthermore, such calculated translation tables are readily available for many of the known statins.

The compounds of the invention in the final formulation containing the required conventional non-toxic pharmaceutically acceptable carriers, adjuvants and vehicles may be administered orally, parenterally, rectally or topically, by inhalation or by aerosol. Topical administration may also include the use of transdermal administration, such as a transdermal patch or iontophoresis device. The term "parenteral" as used herein includes subcutaneous injections, intravenous, intramuscular, intramembranous injections or infusion techniques.

Injectable preparations, for example, sterile injectable aqueous or oleaginous suspensions may be formulated according to the known art using suitable dispersing or wetting agents and suspending agents. The sterile injectable preparation may also be a sterile injectable solution or suspension in a non-toxic parenterally-acceptable diluent or solvent. Water, ringer's solution and isotonic sodium chloride are among the acceptable carriers and solvents. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose, any bland fixed oil may be employed including synthetic mono-or diglycerides in addition to the fatty acids such as oleic acid found in the preparation of injectables.

Liquid dosage forms for oral administration may include pharmaceutically acceptable emulsions, solutions, suspensions, syrups and elixirs containing inert diluents commonly used in the art, such as water. Such compositions may also contain adjuvants such as wetting agents, emulsifying and suspending agents, and sweetening, flavoring, and the like.

Newer statin nitro derivatives, in addition to lowering lipids, have enhanced anti-inflammatory, anti-platelet, and anti-thrombotic efficacy compared to natural statins. Furthermore, they may also be effective in other pathologies such as acute coronary syndrome, stroke, peripheral vascular diseases such as peripheral ischemia, all conditions associated with endothelial dysfunction such as vascular complications in diabetic patients and atherosclerosis, neurodegenerative diseases such as Alzheimer's Disease (AD) and Parkinson's Disease (PD), autoimmune diseases such as multiple sclerosis.

In an alternative embodiment of the treatment methods described herein, the pharmaceutical formulation comprising a statin is administered to the patient via an injection method. In such embodiments, the pharmaceutical formulation of a statin is a formulation suitable for administration to a patient via an injection method. In addition to intravenous injection, suitable methods of injection include intra-arterial infusion, intramuscular injection, transdermal injection, and subcutaneous injection.

Suitable carriers for intravenous administration include physiological saline or Phosphate Buffered Saline (PBS) and solutions containing solubilizing agents such as glucose, polyethylene glycol and polypropylene glycol and mixtures thereof.

The formulation may comprise an aqueous vehicle. Aqueous vehicles include, by way of example and not limitation, sodium chloride Injection, ringer's Injection, isotonic dextrose Injection, sterile water Injection, dextrose, and sodium lactate ringer Injection (Lactated Ringers Injection). Non-aqueous parenteral vehicles include, by way of example and not limitation, vegetable-derived fixed oils, cottonseed oil, corn oil, sesame oil and peanut oil. Antimicrobial agents, either in bacteriostatic or fungistatic concentrations, must be added to parenteral formulations packaged in multi-dose containers, including phenols or cresols, mercurials, benzyl alcohol, chlorobutanol, methyl and propyl parabens, thimerosal, benzalkonium chloride and benzethonium chloride. Isotonic agents include, by way of example and not limitationSodium chloride and dextrose. Buffers include phosphates and citrates. The antioxidant comprises sodium bisulfate. Local anesthetics include procaine hydrochloride. Suspending and dispersing agents include sodium carboxymethylcellulose, hydroxypropylmethylcellulose and polyvinylpyrrolidone. The emulsifier comprises polysorbate 80Sequestering or chelating agents for metal ions include EDTA. Pharmaceutical carriers also include, by way of example and not limitation, ethanol, polyethylene glycol and propylene glycol for water-miscible vehicles, and sodium hydroxide, hydrochloric acid, citric acid or lactic acid for pH adjustment.

Typically, a therapeutically effective dose is formulated to comprise a statin concentration of at least about 0.1% w/w up to about 90% w/w or more, e.g., greater than 1% w/w. In certain embodiments, the solubilized statin concentration of the formulation will be at least about 3.3 mg/ml.

All numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of significant digits and ordinary rounding approaches.

In certain embodiments, the invention relates to a method of reducing the risk of MI, stroke, revascularization surgery, angina in patients who do not have CHD but have multiple risk factors, reducing the risk of MI and stroke in patients who do not have CHD but have multiple risk factors, reducing the risk of non-fatal MI, fatal and non-fatal stroke, revascularization surgery, hospitalization for CHF, and angina in patients who have CHD, reducing high total cholesterol, LDL-cholesterol, apolipoprotein-B, and triglyceride levels in patients who have primary hyperlipidemia (heterozygous familial and non-familial and mixed dyslipidemia), reducing high triglyceride levels in patients who have hypertriglyceridemia and primary abnormal beta-lipoproteinemia, reducing total cholesterol and LDL-cholesterol in patients who have homozygous familial hypercholesterolemia, reducing the risk of heterozygous familial hypercholesterolemia, mixed dyslipidemia after failure to properly attempt diet therapy; and high total cholesterol, LDL-cholesterol, apolipoprotein-B levels in boys of 10 to 17 years of age, and girls after menarche of homozygous familial hypercholesterolemia as an adjunct to other lipid-lowering therapies (e.g., LDL apheresis) or if such therapies are ineffective.

In particular, non-statin drugs useful in the practice of the present invention are any of the PPAR receptor agonists, including those that are selective for one PPAR receptor subtype and those that are active for two or more receptor subtypes. More particularly, the non-statin drug is a PPAR α agonist such as a fibric acid derivative; PPAR gamma agonists; and dual PPAR alpha/gamma agonists, i.e., those having dual activity for both the alpha and gamma receptor subtypes.

When it is stated that a statin and a non-statin competitively bind to an enzyme or enzyme isoform (i.e., an isoenzyme), it is meant that both the statin and the non-statin bind to the same enzyme or isoenzyme. Poor pharmacokinetic drug interaction is intended to mean an in vivo interaction between a statin and a co-administered non-statin drug in a mammal, particularly a human, that will raise the plasma level of the active open-ring acid statin above that when the statin is administered alone, i.e., in the absence of the co-administered non-statin.

Detailed description of the preferred embodiments

The following examples illustrate various aspects of the present invention. They should not be construed as limiting the claims in any way.

Examples 1 to 3

Examples 1-3 the solubilization method was compared to assess the effect of pH, buffer strength and different mixing methods. In example 1, 100mM disodium phosphate (Na) at pH5.5, 6.5, 7.5 and 8.5₂HPO₄) To prepare a sample. Vortex only the sample. In example 2, 100mM Na at pH5.5, 6.5, 7.5 and 8.5₂HPO₄The sample is prepared and then both vortexed and sonicated. In example 3, 25 or 50mM Na at pH7.5 or 8.5₂HPO₄To prepare a sample.

Example 1

10mg of atorvastatin calcium trihydrate ("AS-Ca") was added to approximately 0.9ml of a solution containing 0.8ml of 34.7% hydroxy-propyl- β -cyclodextrin ("HP β -CD") and 0.1ml of 1M Na2HPO4 in ultrapure water, followed by vortexing at maximum speed for 5 minutes. The pH of the sample was then adjusted to pH5.5, 6.5, 7.5, or 8.5 using 0.85% orthophosphoric acid or 0.1M NaOH. Each sample was vortexed and then ultrapure water was added in an amount sufficient (q.s) to 1.0ml, after which the samples were filtered through a 0.45 μm nylon filter and analyzed by HPLC (see table 1).

Example 2

The formulations of example 2 were prepared in the same manner as those of example 1, except that after vortexing, the formulations of example 2 were additionally sonicated. Samples were analyzed by HPLC (see table 1).

Example 3

10mg of AS-Ca was added to a solution containing 0.8ml of 34.7% HP β -CD and 0.025 or 0.050ml of 1M Na in ultrapure water₂HPO₄About 0.9ml solution, then vortexed for 5 min. The pH of the sample was adjusted to 7.5 or 8.5 using 0.1M NaOH, then ultrapure water was added in sufficient quantity to 1.0ml, after which the sample was vortexed for 5min, filtered, and then analyzed by HPLC (see table 1).

TABLE 1

As a result: the solubility of AS-Ca was greatly improved by adjusting the pH to 6.5 and above.

Examples 4 to 5

The solubility of AS-Ca in the formulations of examples 4 and 5 was compared using different pH adjustment methods to assess the complexation efficiency. In example 4, the pH was adjusted to 9 using NaOH, and then phosphoric acid was added to reduce the pH back to pH 7.0-8.5. In example 5, the pH was adjusted to a pH between 7.0 and 8.5 using 0.85% orthophosphoric acid or 0.1M NaOH.

Example 4

20mg/ml AS-Ca mixture was prepared by adding 20mg AS-Ca to 27.78% HP β -CD, 50mM Na₂HPO₄And ultrapure water, and then phosphoric acid and/or NaOH was added in a sufficient amount to 1 mL. The 20mg/ml mixture of AS-Ca was then vortexed for 5min and sonicated for 15 min.

The pH of the sample was adjusted to pH9.0 using 0.1M NaOH, followed by pH7.0, 7.5, 8.0, or 8.5 using 0.85% orthophosphoric acid. Each sample was vortexed, made up to 1.0ml with ultra pure water, filtered, and then analyzed by HPLC.

Example 5

A mixture of 20mg/ml AS-Ca was prepared by adding 20mg of AS-Ca to about 0.8ml of a mixture of 27.78% HP β -CD, 50mM Na2HPO4 and ultrapure water, followed by addition of phosphoric acid and/or NaOH in a sufficient amount to 1 ml. The 20mg/ml mixture of AS-Ca was then vortexed for 5min and sonicated for 15 min.

The pH of the samples was adjusted to pH7.0, 7.5, 8.0 or 8.5 using 0.85% orthophosphoric acid or 0.1M NaOH. Each sample was vortexed, made up to 1.0ml with ultra pure water, filtered, and then analyzed by HPLC.

As a result: the results are provided in table 2 below.

TABLE 2

Example 6

The relationship between AS-Ca and HP β -CD was investigated by evaluating the complexation efficiency of different concentrations of HP β -CD. Stock solutions of HP β -CD were first prepared at 34.7% and serially diluted to 0.5375% HP β -CD.

Samples were prepared by adding 20mg AS-Ca to 0.8ml HP β -CD dilution (final concentration in 1ml was 27.78% to 0.5375% HP β -CD) and 0.05ml1M Na₂HPO₄To prepare the compound. Each sample was adjusted to ph9.0 using 0.1M NaOH, then vortexed for 5 minutes, and then sonicated for 15 minutes. The pH was then adjusted to 7.5 or 8.5 using 0.85% orthophosphoric acid. The sample was vortexed and sonicated again, then filtered and analyzed by HPLC (seeTable 3).

As a result: the solubility of AS-Ca increased linearly with HP β -CD concentration. Linear regression analysis showed that the minimum amount of HP β -CD required to solubilize AS-Ca to 10mg/ml was 14.4% at pH7.5 and 13.5% at pH 8.5. (see FIG. 1).

TABLE 3

Example 7

Forced degradation and preliminary stability studies showed that AS-Ca solubilized with HP β -CD did not exhibit good stability. Therefore, manifold freeze-dryers were used to evaluate lyophilization to determine if stability could be improved by this method.

100mg of AS-Ca was added to a solution containing 5.333ml of 37.5% HP β -CD and 0.5ml of 1MNa₂HPO₄About 9ml of solution. The samples were vortexed for 5 minutes and then sonicated for 15 minutes. The pH was then adjusted to 9.0 using 0.1M NaOH, after which the samples were vortexed and sonicated again.

Next, the pH of the sample was adjusted to pH8.5 using 0.85% orthophosphoric acid, followed by vortexing and sonication. The sample was made up to 10ml using NaOH and 1% phosphoric acid and brought to a pH of 8.47, filtered and then analyzed by HPLC. The final formulation contained 10mg/ml AS-Ca2+, 20% HP β -CD, 50mM Na₂HPO₄Sufficient volume, ph8.47, was achieved using 0.1M NaOH and 1% phosphoric acid.

As a result: for stability, AS-Ca solubilized with HP β -CD was lyophilized and then placed at 40 ℃ for 1 month along with a control solution of the same mixture. Degradation of freeze-dried AS-Ca is 3.5 percent and degradation of AS-Ca in the solution is 15.5 percent. Thus, the samples are unstable in solution or when lyophilized using a manifold freeze dryer.

Example 8

Atorvastatin was prepared as described in example 6, except it was prepared at 20mg/mL in 30% HP β -CD in 100mM sodium phosphate adjusted to a final pH of 8.5. The sample was then diluted 1: 1 into 8% sucrose solution and transferred to a 5mL vial. Vials were capped with a lyophilization stopper.

The samples were frozen in a rack freezer at-40 ℃ and subsequently held for 60 min. After the freezing step, the condenser was adjusted to-85 ℃ and maintained at this temperature throughout the experiment. The pressure is about 20 millitorr. The shelf temperature was then adjusted to-20 ℃, -10 ℃ and 0 ℃ and held at each temperature for 180min while maintaining the vacuum. Next, the temperature was raised to 10 ℃ and then to 20 ℃ (240 minutes for each step). The temperature was then adjusted to 40 ℃ and held at 40 ℃ until the vacuum was released, the vial removed and visually inspected.

As a result: when AS-Ca was solubilized by HP β -CD and then lyophilized using a shelf freeze-dryer, no degradation (less than 0.1%) was observed after 1 month of storage at 40 ℃. While not wishing to be bound by this theory, the enhanced stability may be due to the rapid removal of water and the low residual moisture level obtained by the conditions of the lyophilization cycle.

Examples 9 and 10

In examples 9 and 10, thiobutyl-ether- β -cyclodextrin ("SBE- β -CD") was evaluated AS a possible alternative to HP β -CD by means of the complexation of AS-Ca with SBE- β -CD. The effect of sodium phosphate and ultrapure water on solubilization of AS-Ca with SBE-. beta. -CD at different pH's was also evaluated.

Example 9

In example 9, the complexation of AS-Ca with SBE-beta-CD was at different pHSodium phosphate buffer of value. 20mg/ml AS-Ca was added to 50-100mM NaH₂PO₄(pH2.13 sample) or Na₂HPO₄(pH7.07, 8.75 and 11.75 samples) in 27.78% SBE- β -CD. Each sample was then vortexed and sonicated, after which the pH was adjusted to 2.13 and 7.07 using 0.85% orthophosphoric acid or 8.75 and 11.50 using 0.1M NaOH. The sample was then vortexed, sonicated, and brought to 1.0ml in sufficient volume using ultrapure water, then filtered and analyzed by HPLC (see table 4 below).

As a result: the solubility of AS-Ca was about 10-fold lower when complexed with SBE- β -CD than when complexed with HP β -CD.

TABLE 4

pH of the sample	Atorvastatin (mg/ml)
		2.13	0.228
7.07	1.993
		8.75	1.267
11.75	1.927

Example 10

In example 10, complexation of AS-Ca with SBE- β -CD was performed in ultra-pure water to investigate the effect of phosphate buffer salts on the ability of SBE- β -CD to complex AS-Ca. Based on the results of the solubility study of example 8, the formulations were tested at neutral and basic pH.

Neutral pH: 20mg/ml AS-Ca was added to 27.78% SBE- β -CD in ultrapure water. After vortexing and sonication of the sample, the pH was determined to be 7.09. The sample was then brought to a volume of 1.0ml with ultra pure water, filtered and analyzed by HPLC. (see Table 5)

Alkaline pH: 20mg/mL AS-Ca was added to 27.78% SBE- β -CD in about 0.8mL of ultrapure water. The samples were treated as described above except that 0.1M NaOH was used to adjust the pH to 11.0 and was sufficient to 1.0 mL.

As a result: the phosphate buffer did not show a significant effect on the solubility of atorvastatin combined with SBE- β -CD.

TABLE 5

pH of the sample	Atorvastatin (mg/ml)
		7.09	1.392
11.0	1.927

Example 11

Additional AS-Ca formulations were prepared using other cyclodextrins, including gamma-cyclodextrin and hydroxy-propyl-gamma-cyclodextrin. The solubility was found to be less than that achieved with SBE-beta-CD or HP beta-CD.

Example 12

In example 12, AS-Ca was solubilized with a co-solvent to assess co-solvent/water solubility AS a function of pH. The dependence of pH on propylene glycol and ethanol co-solvent formulations was specifically examined.

10mg of AS-Ca was added to about 0.9ml of a solution containing 4.0ml of propylene glycol and 1.0ml of ethanol in ultrapure water. Samples were vortexed and sonicated, as described above, and then adjusted to ph9.0 using 0.1M NaOH. The sample was vortexed and sonicated again, and then the pH was adjusted to pH7.0, 7.5, 8.0, or 8.5 using 0.85% orthophosphoric acid, or maintained at pH 9.0. The sample was vortexed, sonicated, and the sample was brought to 1.0ml with ultrapure water, filtered, and then analyzed by HPLC. (see Table 6)

As a result: there was no difference in solubility when the pH was changed from 7.0 to 9.0. However, samples adjusted to pH7.5 and 8.0 precipitated when the samples were diluted 1: 1 into water. Thus, when the product is to be diluted in an aqueous vehicle, a pH > 8.0 is preferred.

TABLE 6

pH of the sample	Atorvastatin (mg/ml)
		9.00	9.280
8.50	9.506
		8.00	8.641
7.50	9.361

7.00

8.876

Example 13

Example 13 the amount of solvent required to solubilize AS-Ca was examined by assessing the co-solvent/water solubility AS a function of the co-solvent ratio.

10mg of atorvastatin calcium was added to about 0.9ml of a solution in ultrapure water containing the following solvent ratios:

a.40/10, 4.0ml of propylene glycol and 1.0ml of ethanol

b.30/10, 3.0ml of propylene glycol and 1.0ml of ethanol

c.20/10, 2.0ml of propylene glycol and 1.0ml of ethanol

d.40/5, 4.0ml of propylene glycol and 0.5ml of ethanol

e.40/0, 4.0ml of propylene glycol and 0.0ml of ethanol.

Samples were vortexed for 5min each, and then sonicated for 15 min. The samples were first adjusted to ph9.00 using 0.1M NaOH, vortexed, and then sonicated. The pH of the sample was adjusted to pH8.50 using 0.85% orthophosphoric acid, and the sample was vortexed and sonicated again. The sample was made up to 1.0ml with ultra pure water, filtered and then analyzed by HPLC (see Table 7).

As a result: the best solubility was achieved with 40% propylene glycol (v/v) and 10% ethanol (v/v). Forced degradation studies have shown that any solution of less than 40% propylene glycol and 10% ethanol causes atorvastatin to precipitate when diluted with normal saline.

TABLE 7

Sample (I)	PG/EtOH	Concentration mg/ml
			A	40/10	21.27
B	30/10	17.87
			C	20/10	16.80
D	40/5	18.11
			E	40/0	16.06

Example 14

Forced degradation studies also showed that significant degradation occurred using the cosolvent/aqueous vehicle. Thus, the non-aqueous co-solvents were examined.

10mg of AS-Ca was added to 1.0ml of propylene glycol and ethanol (4/1). The sample was vortexed and then the pH of the sample was adjusted to pH11.0 using 0.1M NaOH. The sample was then filtered and analyzed by HPLC.

As a result: the sample was completely soluble (9.34 mg/ml). When the solution was diluted 1: 3 in saline, the solution precipitated.

Example 15

Forced degradation analysis showed that AS-Ca was relatively stable at high pH. Therefore, L-arginine (L-Arg), NaOH or sodium phosphate buffer (trisodium phosphate (Na) was used₃PO₄) Or Na₂HPO₄) To adjust the pH.

20mg of AS-Ca was added to about 0.8mL of the lower solution 1-5 followed by vortexing and sonication. The pH of the sample was adjusted to basic pH, followed by a volume of 1mL with ultrapure water, vortexing, sonication, filtration, and HPLC analysis.

Solution 1: 20mg of AS-Ca was added to water containing 16.54mM L-Arg (1: 1 atorvastatin: L-Arg molar ratio). The pH was adjusted to 10.98 using 10% L-Arg. The AS-Ca concentration obtained was 0.46 mg/ml.

Solution 2: 20mg of AS-Ca was added to water and the pH was adjusted to 11.68 using 0.1M NaOH. The AS-Ca concentration obtained was 0.222 mg/ml.

Solution 3: 20mg of AS-Ca was added to a solution containing 0.1M Na₃PO₄In the water of (2). The measured pH was 11.75. The AS-Ca concentration obtained was 0.46 mg/ml.

Solution 4: 20mg of AS-Ca was added to a solution containing 0.1M Na₃PO₄And 16.54mM L-Arg in water. The measured pH was pH 10.79. The AS-Ca concentration obtained was 3.17 mg/ml.

Solution 5: 20mg of AS-Ca was added to a solution containing 0.1M Na₂HPO₄And 16.54mM L-Arg in water. The measured pH was 10.79. The AS-Ca concentration obtained was 3.43 mg/ml.

As a result: the solubility of AS-Ca in alkaline solutions without HP β -CD varied from-0.2 mg/mL to 3.5 mg/mL. 16.54mM L-Arg and 0.1M Na were used₃PO₄Or Na₂HPO₄Resulting in AS-Ca concentrations of > 3 mg/mL. Thus L-Arg and Na are used₃PO₄Or Na₂HPO₄The combination of (a) also provides sufficient solubility to prepare AS-Ca in solution.

Examples 16 to 19

Atorvastatin free acid solubility ("AS") was tested AS a replacement for the calcium trihydrate form.

Example 16

Solubility of complexed AS was determined by examining AS-Ca in 50mM Na adjusted to pH10.35 and 10.65, respectively, using 0.1M NaOH₂HPO₄27.78% HP-beta-CD or SBE-beta-CD. The same solubilization method as in example 4 was used.

As a result: AS solubility was 13.3mg/ml for HP β -CD and 1.96mg/ml for SBE- β -CD.

Example 17

In example 17, the use of co-solvents to solubilize AS was evaluated by testing whether AS could be dissolved in a non-aqueous co-solvent at high pH, then diluted into brine without precipitation. The previous data (example 13) show that AS-Ca precipitates when prepared in a non-aqueous cosolvent and then diluted into brine.

20mg AS (20mg) was added to about 0.9ml propylene glycol and ethanol (4/1 ratio) co-solvent. The measured pH was 6.64. The pH was adjusted to pH11.0 using 0.1M NaOH and sufficient ultrapure water was used to give a volume of 1 mL. The sample was then vortexed, filtered, and then analyzed by HPLC.

As a result: the sample degraded rapidly (about 50% in 2 hours). The peak area is conserved between atorvastatin and its degradation peak (conserve). The AS concentration was estimated to be about 20 mg/ml.

Example 18

In example 18, the AS solubility in 100% propylene glycol or 100% ethanol was similar to the AS solubility in propylene glycol/ethanol (4/1) solvent using the same solubilization procedure described above. Atorvastatin free acid is completely soluble in 100% propylene glycol or 100% ethanol, similar to the propylene glycol/ethanol (4/1) solvent. Both solutions precipitated when diluted 1: 1 with saline and were found to be unstable.

Example 19

In example 19, the solubility of AS was determined by using L-arginine (L-Arg), NaOH or sodium phosphate buffer ((Na)₃PO₄) Or Na₂HPO₄) Adjust to high pH for testing.

20mg of AS was added to about 0.8ml of the lower solution followed by vortexing and sonication. The pH of the sample was adjusted to alkaline pH, followed by a volume of 1mL with ultrapure water. The sample was then vortexed, sonicated, filtered, and analyzed by HPLC.

Sample 1: 20mg of AS was added to a 16.54mM L-Arg solution. The measured pH was 10.35, and then the pH was adjusted to 10.71 using L-Arg. The AS-Ca concentration obtained was 1.91 mg/ml.

Sample 2: 20mg of AS was added to ultrapure water, and the pH was adjusted to 11.15 using 0.1M NaOH. The AS concentration obtained was 0.06 mg/ml.

Sample 3: 20mg of AS was added to 16.54mM L-Arg and 0.1M Na3PO 4. The measured pH was 11.42. The AS concentration obtained was 0.44 mg/ml.

Sample 4: 20mg of AS was added to 0.05M Na₃PO₄In (1). The measured pH was 11.55. The AS concentration obtained was < LOQ (limit of quantitation).

As a result: AS in the presence of Na₃PO₄NaOH or Na₃PO₄And L-Arg has a solubility in an alkaline solution of < 1.0 mg/mL. When L-Arg alone was used, AS solubility was 1.91 mg/mL. Thus the use of L-Arg at elevated pH provides sufficient solubility.

Conclusion

Non-aqueous formulations consisting essentially of propylene glycol/ethanol (4/1) at ph11.0 were tested to reduce the degradation observed. However, the formulation precipitates when diluted 1: 1 into normal saline. To improve stability, preliminary lyophilized formulations of AS-Ca and HP β -CD were tested. The initial stability of the formulation was shown to exceed the stability in leaving the sample in solution.

It will be readily apparent to one of ordinary skill in the relevant art that other suitable modifications and adaptations to the methods and applications described herein are suitable and can be made without departing from the scope of the invention or any embodiment thereof. While the invention has been described in connection with certain embodiments, it is not intended to be limited to the specific form set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the following claims.

Claims (16)

1. A liquid pharmaceutical formulation comprising an effective amount of atorvastatin complexed with hydroxy-propyl-E-cyclodextrin in an aqueous solution comprising an effective amount of a pharmaceutically acceptable buffer and/or an alkalinizing agent to provide a pH from 7 to 9, the solubilized atorvastatin concentration in said aqueous solution being from 1mg/ml to 25 mg/ml.

2. The formulation of claim 1, wherein the complexed atorvastatin is lyophilized.

3. The formulation of claim 1, the liquid pharmaceutical formulation having a solubilized atorvastatin concentration of at least 3.32 mg/ml.

4. The formulation of claim 1, wherein the buffer comprises a sodium phosphate buffer or a sodium bicarbonate buffer.

5. The formulation of claim 1, wherein the hydroxy-propyl-E-cyclodextrin comprises at least 13.5% of the formulation.

6. The formulation of claim 1, wherein the solubilized atorvastatin concentration is 5 to 15 mg/ml.

7. The formulation of claim 6, wherein the solubilized atorvastatin concentration is about 10 mg/ml.

8. The formulation of claim 1, wherein the alkalizing agent is NaOH, KOH, triethylamine, meglumine, or L-arginine.

9. The formulation of claim 1, wherein the atorvastatin is atorvastatin calcium trihydrate.

10. A lyophilized particle comprising atorvastatin complexed with a sufficient amount of hydroxy-propyl-E-cyclodextrin, and a pharmaceutically acceptable buffer and/or alkalizer for adjusting the pH to a pH of from 7 to 9 when the lyophilized particle is reconstituted in a pharmaceutically acceptable solution for injection such that the atorvastatin is dissolved in water to provide a solubilized atorvastatin concentration of from 1mg/ml to 25 mg/ml.

11. The lyophilized particles of claim 10, which degrade less than about 0.1% after 1 month of storage at 40 ℃.

12. The lyophilized particles of claim 10, wherein the buffer comprises a sodium phosphate buffer or a sodium bicarbonate buffer.

13. The lyophilized particle of claim 10, wherein the alkalizing agent is NaOH, KOH, triethylamine, meglumine, or L-arginine.

14. The lyophilized particles of claim 10, wherein the atorvastatin is atorvastatin calcium trihydrate.

15. The lyophilized particles of claim 10, which are reconstituted to an atorvastatin concentration of 5 to 15 mg/ml.

16. The lyophilized particles of claim 10, which are reconstituted to an atorvastatin concentration of about 10 mg/ml.