In-vial deposition of stable, sterile and crystalline o-acetyl salicylic acid (aspirin)

Abstract

To provide improved, stable aspirin formulations for intravenous use, as well as applications thereof.SOLUTION: A lyophilized aspirin composition is provided, the composition comprising a lyophilized mixture of crystalline aspirin in the free acid form, a bulking agent, and a surfactant. Also provided is the use of the lyophilized aspirin composition in the manufacture of a medicament for aspirin therapy by intravenous administration to a mammal in need thereof, the manufacture comprising reconstituting the lyophilized aspirin composition with water comprising a basic agent in an amount sufficient to provide an aspirin solution having a pH of at least 5.5.SELECTED DRAWING: None

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 512,367, filed May 30, 2017, the contents of which are incorporated herein by reference.

[0002] The present invention is directed to stable forms of injectable aspirin, kits containing same, and methods of treatment using same. [Background technology]

[0003] Aspirin (O-acetylsalicylic acid, ASA) has been used therapeutically for over 100 years. As a salicylic acid derivative, aspirin possesses three properties of nonsteroidal anti-inflammatory drugs (NSAIDs): analgesic, antipyretic, and anti-inflammatory, in the treatment of arthritis, neuralgia, and muscle pain. In addition to these three properties, aspirin is also effective in inhibiting platelet aggregation.

[0004] The primary therapeutic effect of NSAIDs, such as aspirin, is their ability to inhibit prostaglandin production. Aspirin covalently modifies both COX-1 and COX-2, irreversibly inhibiting cyclooxygenase activity, unlike other NSAIDs that reversibly bind to COX. Inhibition of COX-1 inhibits platelet aggregation but may also stimulate the gastric lining and renal function. Inhibition of COX-2 results in anti-inflammatory, antipyretic, and analgesic effects.

[0005] Due to the multiple therapeutic activities of aspirin and salicylic acid (SA), including the treatment of mild to moderate pain and fever, chronic diseases such as reducing the risk of thrombotic cardiovascular events, and, as new evidence suggests, reducing the risk of colorectal cancer, aspirin has taken on many different shapes and sizes. Aspirin was first synthesized in 1897 and was sold as a tablet for several decades, but over the past 30 or 40 years, a variety of dosage forms have been introduced, including plain tablets, chewable tablets, effervescent tablets, sustained-release tablets, granules and suspensions, immediate-release / disintegrating tablets, suppositories, powders, creams, and lotions.

[0006] Aspirin is a drug that exists primarily in a slightly soluble, undissociated form in water (approximately 0.3%), insoluble at acidic pH, and its solubility increases significantly above pH 5.5. Aspirin solubility is greater than 100 mg / ml above pH 5.5. Aspirin hydrolyzes to form salicylic acid under all pH conditions. The rate of hydrolysis is slowest at approximately pH 2.5. Aspirin hydrolysis remains consistent across the pH range of 4.5 to 8.5. Its degradation half-life is approximately 6 days, insufficient for the development of a solution formulation. Lyophilization of concentrated bulk solutions is also not possible because aspirin's degradation half-life is so short that a 10% loss of potency can be observed in approximately 1.3 hours. To lyophilize any drug, the bulk solution must remain potent for at least 12 hours under ambient conditions. Even at pH 2.5, where aspirin hydrolysis is slowest, aspirin degrades at a rate of approximately 2% per day. The low solubility combined with poor solution stability precludes the development of a commercially viable lyophilizate, making it extremely difficult to develop an aspirin injection in the form of a solution in an aqueous medium or in a lyophilized form.

[0007] Due to these solubility and stability problems in injectable dosage forms, only oral aspirin is widely used to treat the various indications mentioned above. However, orally administered aspirin is not completely absorbed and has a slow onset of pharmacological action. Meanwhile, the efficacy of intravenously administered aspirin solution has been reported to be four times greater than that of an equivalent amount of orally administered acetylsalicylic acid.

[0008] This degradation reaction was known to be pH dependent: a decrease in pH caused the released lysine to become increasingly protonated, making it unavailable or only available to a very limited extent for subsequent reaction with O-acetylsalicylic acid.

[0009] All attempts to develop a stable injectable formulation of O-acetylsalicylic acid (ASA) have failed, despite extensive development efforts over the past 50 years. In the opinion of the inventors, salts of O-acetylsalicylic acid with amino acids containing two basic groups are unstable due to disproportionation of the salt components. When the salt is dissolved in water, it may remain, resulting in ionization equilibrium and the formation of aspirin and amine salt formers.

[0010] The aqueous solubility of the aspirin thus formed is very low compared to that of the salt, and it tends to precipitate, so an equilibrium occurs to restore it, but at the same time, more amine salt formers are formed. In this way, the pH of the solution increases and it becomes more unstable. Under high pH conditions, O-acetylsalicylic acid is deamidated to form O-acetylsalicylic acid and amino acid derivatives of O-salicylic acid. The presence of such impurities in an injectable formulation of aspirin is undesirable.

[0011] Since the discovery of aspirin in 1859 and its subsequent worldwide commercialization by Bayer in 1899, O-acetylsalicylic acid (ASA, aspirin; Aspirin® is a registered trademark of Bayer) has been a medical backbone drug for the treatment of pain, fever, inflammation, and the inhibition of platelet aggregation in thrombotic (blood clot) situations.

[0012] Aspirin is the only common small molecule drug that also has the inherent ability to inhibit platelet aggregation in the blood and therefore prevent, reduce, or eliminate platelet-based clots in blood vessels, tissues, and vital organs. Aspirin is only available as an oral tablet or capsule that must be taken by mouth and then absorbed by the stomach and GI tract, with the onset of inhibition of platelet aggregation occurring approximately 40 minutes after oral administration.

[0013] Treating platelet thrombosis in the setting of a heart attack or stroke can be lifesaving within minutes. Compared to fast-acting IV thrombolytic drugs, such as TPA, low molecular weight heparin, and glycoprotein IIb / IIIa inhibitors, oral tablet aspirin administered in an ambulance or ER is not fast acting.

[0014] Hundreds of millions of people experience acute (sudden) pain in the setting of headaches, migraines, arthritis, musculoskeletal or skin trauma, fractures, dental and surgical wound pain, and from complications of cancer and diabetes. Many painkillers, including aspirin, are available as oral tablets and require approximately 30 minutes for the onset of pain relief. Opioid analgesics are currently available in immediate- and sustained-release dosage forms and require approximately 30 minutes for the onset of pain relief. However, opioids are widely known to be highly addictive and can cause cardiorespiratory failure at standard or excessive doses. Summary of the Invention [Problem to be solved by the invention]

[0015] Thus, there is a continuing search for effective, "fast-acting," predictably tolerable agents for the inhibition of platelet-mediated thrombosis, as well as non-addictive drugs for the treatment of acute pain, fever, and inflammation. Thus, there is a great medical need for a parenteral dosage form of aspirin that provides immediate therapeutic action in acute coronary syndromes and other vascular indications. [Means for solving the problem]

[0016] In one embodiment of the present invention, a liquid aspirin-containing composition with enhanced stability is provided. The bulk solution composition comprises aspirin and a co-solvent containing an organic solvent and water, the ratio of organic solvent to water being about 95 / 5 to 50 / 50.

[0017] Another aspect of the present invention provides the use of a liquid aspirin-containing composition as a bulk solution for producing lyophilized aspirin. A still further aspect of the present invention includes a method for producing lyophilized aspirin. The method includes obtaining a liquid aspirin-containing composition described herein, lyophilizing the composition, and recovering the resulting lyophilized aspirin. The liquid aspirin-containing composition may contain about 20 to about 100 mg / ml of aspirin, and the cosolvent may include t-butyl alcohol and water. Lyophilized aspirin produced by the methods described herein is also an aspect of the present invention. Such lyophilized aspirin has a shelf life of at least two years under ambient storage conditions.

[0018] A still further embodiment of the present invention includes a kit for aspirin therapy, comprising a first container containing a therapeutic amount of lyophilized aspirin and a second container containing water and a basifying agent, and optionally a surfactant, e.g., polysorbate 80. Suitable basifying agents include amino acids or organic bases, and inorganic bases or basic salts of alkali and alkali metals, with a pKa of 8.5 or greater. The amount of basifying agent is sufficient to provide a solution obtained by combining the contents of the first and second containers with a pH of at least about 5.5 and preferably 6.0, or about physiological pH.

[0019] Another aspect of the invention is an intravenous liquid aspirin-containing composition prepared by combining the contents of the first and second containers of the kit described herein.A method of providing aspirin therapy comprising intravenously administering to a mammal in need thereof an effective amount of an intravenous liquid aspirin-containing composition described herein. [Brief explanation of the drawings]

[0020] [Figure 1a] FIG. 1 shows X-ray diffraction patterns of aspirin API and lyophilisates made at various concentrations according to the present invention and Example 18. [Figure 1b] FIG. 1 shows X-ray diffraction patterns of aspirin API and lyophilisates made at various concentrations according to the present invention and Example 18. [Figure 1c] FIG. 1 shows X-ray diffraction patterns of aspirin API and lyophilisates made at various concentrations according to the present invention and Example 18. [Figure 1d] FIG. 1 shows X-ray diffraction patterns of aspirin API and lyophilisates made at various concentrations according to the present invention and Example 18. [Figure 2] FIG. 1 shows an XRD overlay of the test sample of Example 21. DETAILED DESCRIPTION OF THE INVENTION

[0021] The aqueous solubility of aspirin is approximately 3 mg / ml. This concentration is too low to administer a sufficient dose of aspirin. For example, to administer 100 mg, approximately 33.3 ml of aspirin solution is required. This volume is too large for a bolus injection. A diluted solution must be administered via rapid injection. The larger the dose, the larger the volume of aspirin solution required. Furthermore, the solution is acidic, with a pH of approximately 2.5. Therefore, aspirin solutions must be formulated at approximately physiological pH to avoid injection site pain and hemolysis. Because aspirin solutions are inherently acidic, one method for neutralizing acidic solutions is treatment with an inorganic base. A second approach known in the art is to prepare basic organic salts of aspirin. Over the past 40 years, several scientists have focused on preparing basic salts of aspirin. A notable or widely popular salt form of aspirin is the lysine salt. Extensive research and development efforts were conducted on this salt form, but it was found to be less stable than aspirin. Therefore, clinical use of this salt form was limited to a few hospitals in Germany. Bayer sells this product to a few hospitals with a one-year shelf life. The product sold by Bayer is a sterile dry powder consisting of 500 mg of aspirin and 906 mg of aspirin lysine salt, equivalent to 406 mg of l-lysine. Additionally, the product offered on the market contained approximately 50-100 mg of glycine as a stabilizer. The product is considered to be a sterile, dry-filled mixture of aspirin lysine salt and glycine. This sterile dry mixture was combined with 5 ml of water for injection to obtain a solution containing 100 mg / ml of ASA. The 5 ml solution was injected in less than two minutes. Thromboxane B2 was inhibited by more than 95% within five minutes of bolus injection. Because thromboxane inhibition prevents platelet aggregation, injectable ASA is expected to be life-saving for people suffering from heart attacks.

[0022] Our goal was to develop a stable, sterile, injectable form of pure aspirin in a vial that could be reconstituted with a special diluent to obtain a 100 mg / ml ASA solution. Extensive studies were conducted on physical mixtures of aspirin with amino acids, co-lyophilization with amino acids, and non-aqueous lyophilization. Among the amino acids tested were arginine, lysine, and glycine. Inorganic basifying agents, such as dibasic and tribasic sodium phosphate, sodium hydroxide, magnesium hydroxide, and calcium hydroxide, were also tested. Combinations of amino acids to deprotonate acetylsalicylic acid and inorganic basifying agents to control the pH of the bulk solution were also tested.

[0023] In a first aspect of the present invention, a liquid aspirin-containing composition with enhanced stability is provided. This composition is useful as a bulk solution for producing lyophilized aspirin. The composition comprises aspirin and a co-solvent containing an organic solvent and water. The ratio of the organic solvent to the water is about 95 / 5 to 50 / 50.

[0024] The organic solvent is preferably an alcohol, such as a C2-C4 alcohol. For example, suitable alcohols include t-butyl alcohol (TBA), n-butanol, ethanol, and mixtures thereof. In many embodiments of the present invention, the alcohol is t-butyl alcohol. The ratio of alcohol to water can be from about 60:40 to about 80:20. In some embodiments, it is preferably from about 65:35 to about 75:25.

[0025] The concentration of aspirin in the composition can be from about 25 mg / ml to about 115 mg / ml, and in some embodiments, it is preferably from about 45 mg / ml to about 75 mg / ml or about 50 mg / ml.

[0026] The liquid aspirin-containing composition may further comprise a surfactant, preferably in an amount of about 0.05 to about 0.5 mg / ml. Suitable surfactants include any pharmaceutically acceptable surfactant known to be useful in lyophilized formulations. In some embodiments, the surfactant is polysorbate 80 or Tween 80.

[0027] The liquid aspirin-containing composition may also include a solubility enhancer, preferably in an amount of about 2 to about 30 mg / ml, preferably about 5 to about 20 mg / ml. Suitable solubility enhancers include, but are not limited to, sucrose or a sugar alcohol, such as mannitol, or other pharmaceutically acceptable sugar alcohols known to those of skill in the art.

[0028] The liquid aspirin-containing compositions of the present invention may also include buffers with a pKa above 8, such as Tris, i.e., tris(hydroxymethyl)aminomethane, glycine, or other amino bases.

[0029] The liquid aspirin-containing composition is suitable for use as a bulk solution in the manufacture of lyophilized aspirin. The resulting lyophilized composition is surprisingly stable, with minimal degradation of aspirin to salicylic acid. For example, compositions according to the present invention exhibit degradation levels of ≦about 2%, preferably ≦about 1%, ≦about 0.5%, or ≦about 0.25% after 24 hours at ambient temperature.

[0030] One preferred liquid aspirin-containing composition according to the present invention is one in which the co-solvent is a mixture of TBA and water in a ratio of about 65:35 to about 75:25, the aspirin is present in an amount of about 45 to about 75 mg / ml, and the composition further comprises about 0.05 to about 0.5 mg / ml polysorbate 80 and about 5 to about 25 mg / ml mannitol.

[0031] In another embodiment of the invention, the bulk liquid aspirin-containing composition comprises a co-solvent combination including TBA / water, n-butanol / water, ethanol / water, PEG-ethanol / water, DMSO / water, DMF / water, or PEG / n-butanol / water.

[0032] The present invention also includes a method for producing lyophilized aspirin. The method includes providing a liquid aspirin-containing composition as described above, lyophilizing the composition, and recovering the resulting lyophilized aspirin. Techniques for lyophilizing aspirin will be apparent to those skilled in the art based on the disclosures provided in the Examples. The liquid aspirin-containing composition prior to lyophilization may contain about 20 to about 100 mg / ml of aspirin, and the cosolvent may comprise t-butyl alcohol and water, with the ratio of t-butyl alcohol to water being about 80:20 to about 60:40. In some embodiments of the present invention, the lyophilized aspirin is crystalline and has a melting point in the range of 136°C to 144°C as determined by differential scanning calorimetry (DSC).

[0033] Lyophilized aspirin produced according to the present invention may have a shelf life of at least 2 years under ambient storage conditions, preferably having less than about 2.0% total degradants after 2 years at 25°C, and more preferably less than about 1.5% by weight or even less salicylic acid after 2 years at 25°C.

[0034] In many embodiments, the lyophilized aspirin of the present invention also has low levels of residual t-butyl alcohol in the lyophilized aspirin, less than about 0.5%, preferably in an amount of about 500 to about 10,000 ppm or about 1,000 to about 3,000 ppm.

[0035] Another feature of the lyophilized aspirin produced according to the present invention is that it has a concentration of about 50, 75, or 100 mg / ml when lyophilized from bulk solution. The lyophilized aspirin may have a particle size distribution, for example, as shown below:

[0036] [Table 1]

[0037] In an illustrative example of conversion of a bulk solution into individual containers containing unit doses of lyophilized aspirin, the bulk solution is shown to contain co-solvents in the following ratios:

[0038] [Table 2]

[0039] The vials containing the solution are then lyophilized. The fill amount is calculated based on 350 mg of aspirin per vial, which is reconstituted to 100 mg / ml with, for example, 3.5 ml of diluent in the second container of the kit. This excess amount allows the practitioner to retrieve 3.25 ml of solution, and therefore 325 mg of aspirin, from the vial.

[0040] The present invention also includes kits for aspirin therapy containing a first container containing a therapeutic amount of lyophilized aspirin, e.g., about 325 mg, and a second container containing water and a basifying agent for reconstituting the lyophilized aspirin. The second container further contains a surfactant, preferably at a concentration of about 0.01 to about 0.4 mg / ml, more preferably about 0.2 mg / ml. In many embodiments of the present invention, the surfactant is polysorbate 80.

[0041] The basifying agent can be selected from suitable amino acids, organic bases, and inorganic bases, or alkali and alkali metal basic salts, for example, those with a pKa of 8.5 or higher. Some suitable amino acids include arginine, lysine, and glycine. A suitable example is Tris. Examples of suitable inorganic bases or salt forms include sodium carbonate, sodium bicarbonate, and dibasic sodium phosphate.

[0042] The amount of basifying agent contained in the second container is sufficient to provide a solution obtained by combining the contents of the first and second containers at a pH of at least about 5.5, preferably about 6.0, and more preferably about 6.0 to about 7.4, or at about or near physiological pH.

[0043] The present invention further includes an intravenous liquid aspirin-containing composition prepared by combining the contents of the first and second containers of the kit. Such a composition preferably has an isotonicity of about 270 to about 1300 mOsm / kg.

[0044] In accordance with the foregoing, one liquid aspirin-containing composition for intravenous injection contains about 20 to about 140 mg / ml, preferably about 100 mg / ml, of aspirin, a sugar alcohol, preferably mannitol, and a surfactant, with less than about 0.1% TBA in the composition.

[0045] The present invention also includes methods for providing aspirin therapy. The methods involve intravenously administering an effective amount of an intravenous liquid aspirin-containing composition described herein to a mammal, e.g., a human, in need thereof. Indeed, the methods also involve combining the contents of two containers, preferably provided in kit form, optionally including instructions for use of the aspirin composition, and administering the resulting composition intravenously. The amount of aspirin administered intravenously can be from about 80 to about 1200 mg, preferably from about 300 to about 1000 mg. In some embodiments of the present invention, the container containing the lyophilized aspirin contains an amount sufficient to deliver 325 mg of aspirin in a 3.25 ml dose.

[0046] The aspirin concentration of the intravenously administered composition can be about 20 to about 100 mg / ml, or higher if desired, and the volume of the intravenously administered aspirin-containing composition is about 1 ml to about 10 ml. In some preferred embodiments, the concentration of aspirin administered is about 100 mg / ml.

[0047] The intravenous aspirin-containing composition can be administered intravenously over a period of about 120 seconds or less, preferably about 90 seconds or less. Such an administration method is particularly well suited for treating platelet thrombosis in the setting of a heart attack or stroke. Thus, the compositions of the present invention can be advantageously provided in ambulances and emergency carts used in hospitals and emergency rooms to provide immediate therapeutic action for acute coronary syndrome conditions.

[0048] Further treatment options The reconstituted aspirin compositions described herein can be used in any aspirin therapy known to those skilled in the art. For example, the aspirin therapy can be used to treat at least one of the following, but is not limited to: a) Vascular indications including ischemic stroke, TIA, acute MI, prevention of recurrent MI, unstable angina, and chronic stable angina; b) reduced risk of combined fatal and non-fatal stroke or transient cerebral ischemia due to fibrin-platelet embolism; c) reducing the risk of vascular mortality in patients with suspected acute MI; d) reduced risk of combined fatal and non-fatal MI in patients with a history of MI or unstable angina, and (4) reduced risk of combined MI and sudden death in patients with chronic angina; b) Revascularization (coronary artery bypass grafting (CABG), percutaneous transluminal coronary angioplasty (PTCA), and carotid endarterectomy): Aspirin is indicated for patients undergoing revascularization (i.e., CABG, PTCA, or carotid endarterectomy) if there is a history of aspirin already being indicated; c) Rheumatic Disease Indications (rheumatoid arthritis, juvenile rheumatoid arthritis, spondyloarthropathy, osteoarthritis, and arthritis and pleurisy due to systemic lupus erythematosus (SLE)): Aspirin is indicated for the relief of symptoms of arthritis and pleurisy associated with rheumatoid arthritis, juvenile rheumatoid arthritis, osteoarthritis, spondyloarthropathy, and SLE; and d) Kawasaki disease or mucocutaneous lymph node syndrome.

[0049] When the indication is Kawasaki disease, the amount of aspirin administered is about 80 to about 100 mg per kg of body weight per day, or about 3 to 5 mg per kg of body weight per day. Other dosing regimens will be apparent to those skilled in the art without undue experimentation. [Example]

[0050] [Example 1] First, the chemical stability of molar equivalent physical blends of aspirin and lysine and aspirin and glycine was evaluated. In the first experiment, 5 g of aspirin and 4.06 g of l-lysine were thoroughly mixed in a mortar and pestle, and the blend was passed through a 100-mesh screen. The physical blend (906 mg, equivalent to 500 mg of aspirin) was weighed into several 5 mL, type I flint glass vials, stoppered, and capped. These vials were placed at 40°C and 25°C and stored for up to 3 months before being analyzed for aspirin and salicylic acid (the major degradant of aspirin).

[0051] Similarly, a physical mixture of 5 g of aspirin and 2.08 g of glycine was prepared and the stability of this physical mixture was similarly evaluated. The stability data are shown in Table 1.

[0052] [Table 3]

[0053] Stability data suggests that the aspirin-lysine physical blend is not very stable, as a loss of approximately 6% potency was observed, along with a corresponding increase in salicylic acid, the primary degradant of aspirin. Stability assessment is based on the formation of salicylic acid during storage. The amount of salicylic acid should not exceed 3% over the shelf life. However, analysis of an aspirin-lysine physical blend stored at 25°C after 3 months showed the formation of approximately 5% salicylic acid, and approximately 7.5% salicylic acid at the end of 1 year of storage, indicating the physical blend is unstable.

[0054] However, the aspirin-glycine physical blend demonstrated no degradation after 3 months of storage at 40°C and 1 year at 25°C, suggesting that developing a robust formulation of an aspirin-glycine physical blend (1:1 on a molar basis) is feasible if sterile aspirin powder can be aseptically blended with sterile glycine and aseptically filled into vials. This is a labor-intensive and costly process, and it can be difficult to source sterile-grade aspirin and glycine. In principle, the physical blend could be non-sterilely filled into vials, and the finished product could be sterilized by gamma irradiation. However, we found in the literature (30) that three degradants were observed upon gamma irradiation of aspirin. Therefore, gamma irradiation is not a viable option for sterilizing aspirin-glycine physical blends.

[0055] [Example 2] Lyophilization of aspirin and lysine was also attempted. Equimolar amounts of aspirin and lysine were dissolved in water to a target aspirin concentration of 50 mg / mL. After 15 minutes of stirring, it was observed that some of the ASA did not dissolve. The pH of the solution was 4.5. An additional amount of lysine was added to raise the pH of the bulk solution to 6.5. When all of the drug dissolved, a clear solution resulted. The solution was then filtered, and 10 mL aliquots of the solution were placed in 20 cc vials and lyophilized to obtain a dose of 500 mg of ASA per vial. However, the product did not lyophilize properly; the lyophilized cake collapsed. HPLC analysis suggested that approximately 40% of the ASA was degraded during the lyophilization process. Based on these data and extensive laboratory studies conducted to produce stable lyophilized formulations using water and an organic base to dissolve the ASA, it was concluded that lyophilization of ASA and lysine or other organic bases using water as the dissolution medium is not feasible.

[0056] [Example 3] In a subsequent series of experiments, inorganic bases / buffers in water were investigated for dissolving ASA. 20 mg / ml ASA slurries were prepared in which ASA was solubilized by increasing the pH to 6.5 using three different techniques: Use of 3A sodium hydroxide pellets 3B Use of disodium hydrogen phosphate 3C: Use of sodium hydroxide powder to raise the pH to 5.0, then disodium hydrogen phosphate to adjust the pH to 6.5. This procedure provided better pH control than 3A.

[0057] All three solutions were filtered, and 5 ml of each was placed in a Type I flint vial and lyophilized. After lyophilization was completed, the vials were observed for physical appearance. The lyophilized cakes in all vials had shrunk and collapsed. HPLC analysis suggested that more than 10% of the ASA had been converted to its major degradant, salicylic acid. The lyophilization of the ASA-lysine solution was performed at approximately -30°C, so all of the water was removed by sublimation at this low temperature. It is unclear whether decomposition occurs during lyophilization, during bulk solution preparation, or a combination of both. Therefore, the bulk solution stability of Example 3C at 25°C was investigated. The stability data are shown in Table 2 below:

[0058] [Table 4]

[0059] As shown in the table above, when all the ASA was dissolved, approximately 3% salicylic acid was initially formed. The level of salicylic acid rose to approximately 9% within 4 hours. From these experiments, it was clear that aqueous lyophilization of ASA was not feasible. A robust manufacturing process should not observe any degradation of ASA in the bulk solution for lyophilization for at least 24 hours.

[0060] [Example 4] Because aqueous lyophilization of ASA is not possible in the weakly acidic (pH 4-6.5) and weakly basic (pH above 7.0) ranges, the use of nonaqueous solvents to improve the bulk solution stability of ASA was investigated. Aspirin is sufficiently soluble in ethanol (80 mg / ml), dimethyl sulfoxide (DMSO) (41 mg / ml), and dimethylformamide (DMF) (30 mg / ml). Pure ethanol cannot be used for lyophilization because it does not freeze and is very difficult to remove during the lyophilization process without damaging the final product. Both DMSO and DMF are caustic solvents, which can damage polymeric materials in the lyophilizer chamber, such as gaskets and other housing materials. Therefore, these two solvents have rarely been used in lyophilization processes. Although some products have used ethanol as a cosolvent with water in lyophilization processes, the ethanol level is limited to 10-15% by volume.

[0061] [Example 5] To overcome the problems associated with freeze-drying using the aforementioned solvents, the use of t-butyl alcohol (TBA) was investigated. However, TBA is not as strong an aprotic solvent as ethanol, DMSO, or DMF. In a first step, the saturated solubility of ASA was measured in pure t-butyl alcohol and in binary solvents containing various ratios of water and TBA. Surprisingly, aspirin was found to be highly soluble in TBA, much higher (approximately 1.5-4 times) than the reported solubility of aspirin in ethanol, DMSO, and DMF. The solubility of aspirin in other C3-C4 aliphatic alcohols, such as n-butanol, n-propanol, and isopropanol, was also measured. The solubility of aspirin in other aprotic solvents, such as propylene glycol and polyethylene glycol 400, was also measured. The data are summarized in Table 3.

[0062] The solubility of aspirin in a TBA / water (60 / 40) mixture was also higher than that of aspirin in pure ethanol. This is indeed an important invention or discovery, because the incorporation of water into the solvent mixture allows for the presence of water-soluble excipients, such as bulking agents, in the bulk solution for lyophilization. For example, if one wishes to co-lyophilize ASA with any basic amino acid or with some inorganic basifying or bulking agents, such as mannitol or sucrose, water is required in the solvent system to dissolve these excipients, since these excipients are insoluble in TBA alone. Table 3 shows the solubility data for ASA in various solvents and TBA / water systems.

[0063] [Table 5]

[0064] As shown in the table above, the solubility of ASA reached its target concentration of 100 mg / mL in an 80% / 20% TBA / water (v / v) system. Note that all references to TBA / water ratios in this literature are on a v / v basis. In general, as the proportion of water increases, the solubility of poorly water-soluble drugs decreases in mixed solvent systems. The same behavior was observed in the TBA / water system.

[0065] Solubility determination procedure: The aliquot of API was added to the vehicle, left on a magnetic stirrer, stirred at 500 RPM, and heated, if necessary, until dissolved. Once a clear solution was obtained, a small amount of additional drug was added to facilitate further dissolution of the drug. This process was repeated until saturated solubility was achieved. The solution was filtered, transferred to a vial, stoppered, crimped, and used for physical observation and HPLC analysis.

[0066] [Example 6] As mentioned previously, the primary criterion for lyophilization is the stability of ASA in bulk solution. A robust lyophilization method requires that the drug not degrade in the bulk solution for lyophilization for at least 24 hours. The 24-hour stability of ASA in 80 / 20, 70 / 30, and 60 / 40 TBA / water solutions was investigated. No appreciable degradation was observed over 24 hours of storage under ambient storage conditions in any of the systems tested. The stability data are shown in Table 4 below.

[0067] [Table 6]

[0068] The physical appearance of the bulk solution remains unchanged during storage: the solution is clear and colorless.

[0069] [Example 7] Based on the information obtained about the solubility and stability of ASA in TBA / water systems, the following lyophilization study was conducted. A 20 mg / ml batch of aspirin was prepared in 80% TBA / 20% water, where the apparent pH of the bulk solution was 2.9. The pH of the solution was raised to 6.5 using 1N sodium hydroxide. Phase separation was observed, likely due to salting out of the inorganic base from the TBA / water system. In a subsequent trial, the pH of the solution was first raised to 5.0 using 1N sodium hydroxide, and then to 6.5 using dibasic sodium phosphate. Dibasic sodium phosphate was used for better pH control. Since phase separation was still observed, it appears that inorganic bases or buffers are not compatible with the 80% TBA / 20% water system. Additional water, e.g., 70% TBA / 30% water, may be required in the system to dissolve the alkalinizing agent.

[0070] [Example 8] We then investigated the possibility of incorporating ASA with organic amino acid bases, such as arginine, lysine, or glycine, in the lyophilization process. Because both lysine and arginine are poorly soluble in an 80 / 20 TBA / water mixture, 70 / 30 TBA / water was used as the solvent for lyophilization. The solubility of arginine in this solvent system is approximately 10 mg / ml, that of lysine is 2 mg / ml, that of glycine is 3 mg / ml, and that of Tris is 5 mg / ml. Inorganic buffers, such as dibasic sodium phosphate, are insoluble in this solvent system. However, these solubility values ​​are not sufficient to neutralize aspirin. Aqueous titration studies indicated that approximately 90 mg of arginine was required to neutralize 100 mg of ASA to produce a 20 mg / ml aspirin solution at a pH of approximately 6.0. Therefore, among the amino acid buffers, arginine and Tris were the only ones with reasonable solubility in the 70 / 30 TBA / water system. Therefore, it is not feasible to incorporate amino acids or inorganic bases other than arginine or Tris at a concentration sufficient to neutralize ASA in the TBA / water solvent for co-lyophilization of ASA. Even this amount of arginine is not sufficient to completely neutralize ASA. In the above test, the solubility of the pure free base of amino acids was also measured without ASA. When ASA is neutralized with arginine free base in a 70% TBA / 30% water system, the solubility of arginine may be different.

[0071] To test our hypothesis, 2 g of ASA was added to 80 ml of a 70 / 30 TBA / water solvent system. Arginine was slowly added to the clear solution to neutralize the aspirin. Approximately 1.8 g of arginine was added to achieve complete dissolution. The batch volume was brought up to 100 ml with the addition of 70 / 30 TBA / water. The measured solubility of arginine was 18 mg / ml, which is significantly higher than the solubility of arginine free base alone (approximately 10 mg / ml). The apparent pH of the bulk solution was 6.28.

[0072] Five-milliliter aliquots were placed in flint vials and lyophilized. After lyophilization was complete, the contents of the vials were reconstituted with 5 ml of water for injection. All of the drug dissolved, but a slight turbidity was observed. The pH of the reconstituted solution was 4.71. The bulk solution for lyophilization had 70% TBA, so the pH value of 6.24 was the apparent pH in a 70 / 30 TBA / water system. The reconstituted solution was essentially free of TBA and was observed to be the true native pH of a 20 mg / ml aspirin solution, suggesting that not all of the ASA was completely neutralized. A pH greater than 6 in aqueous solution indicates complete neutralization of the aspirin.

[0073] [Example 9] In the next trial, the incorporation of sodium hydroxide to promote complete neutralization was investigated. To a slurry of 80 ml of 70 / 30 TBA / water solvent system and 2 g of aspirin, 100 mg of sodium hydroxide was added. Arginine was then slowly added to the slurry to neutralize the aspirin. Approximately 1.6 g of arginine was added to ensure complete dissolution. The batch volume was brought up to 100 ml with the addition of 70 / 30 TBA / water. The apparent pH of the bulk solution was 6.49. Five-ml aliquots were placed in flint vials and lyophilized. After lyophilization was complete, the contents of the vials were reconstituted with 5 ml of water for injection. All of the drug dissolved, although a slight turbidity was observed. The pH of the reconstituted solution was 4.8. The incorporation of a free base such as sodium hydroxide did not neutralize aspirin in the 70% TBA / 30% water system.

[0074] Based on the above studies, it became clear that a large amount of base was required to neutralize ASA in the preferred solvent system. To incorporate more base into the bulk solution, the use of 60 / 40 TBA / water as the lyophilization solvent was investigated. 400 mg of sodium hydroxide was added to 80 ml of the 60 / 40 TBA / water solvent system and 2 g of ASA solution. The batch volume was brought up to 100 ml with the addition of 60 / 40 TBA / water. The apparent pH of the bulk solution was 6.31. 5 ml aliquots were placed in flint vials and lyophilized. After lyophilization was complete, the contents of each vial were reconstituted with 5 ml of water for injection. The drug was nearly completely dissolved, although a slight turbidity was observed. The pH of the reconstituted solution was 4.41. The incorporation of a large amount of base, such as sodium hydroxide, did not solubilize aspirin in the bulk lyophilization solution. The appearance of the lyophilized cake was poor, with shrinkage and some meltback. The lyophilisates were reconstituted with 5 ml of buffer solution containing various concentrations of disodium phosphate. The titration data are shown in Table 5.

[0075] [Table 7]

[0076] Titration data suggested that the solvent system for lyophilization should contain at least 350 mg of dibasic sodium phosphate in addition to 400 mg of sodium hydroxide to raise the pH of the reconstituted solution above 5.

[0077] [Example 10] In all of the above examples, the reconstituted solutions were cloudy. It was unclear whether the cloudiness was due to the low pH or the inherent properties of the lyophilizate. The batches cited in Example 8 were produced and reconstituted to various concentrations using dibasic sodium phosphate with or without neutral and amphiphilic surfactants. The pH of the reconstituted solutions was 4.71. The reconstitution of the lyophilizates to various concentrations in various media is shown in Table 6.

[0078] [Table 8]

[0079] All reconstituted solutions exhibited turbidity at all concentrations, despite achieving the target pH. It was speculated that the turbidity could be due to degradation of aspirin in the bulk solution. Therefore, the lyophilizates were tested for potency and possible degradation products. HPLC analysis indicated a 17.4% loss in potency. Salicylic acid formation was 7.2 area %. Other unknown degradants were observed at less than 0.2 area %. Presumably, the turbidity was due to these unknown degradants. The significant potency loss during lyophilization was a major concern for the development of robust and stable lyophilized formulations of ASA with basic neutralizers. To determine whether the instability was observed in only this batch or in other batches, two batches prepared using 70 / 30 TBA / water as the lyophilization solvent stored under ambient conditions for one month were analyzed. The stability data are shown in Table 7.

[0080] [Table 9]

[0081] As shown in the table above, a loss of approximately 50% potency was observed over one month of storage under ambient conditions. In addition to salicylic acid, three additional degradation products were observed, with salicylic acid being the predominant degradant. Testing suggested that lyophilization of ASA via partial or complete neutralization with an amino acid or inorganic base, or a combination of both, in a solvent system containing TBA / water is not feasible. Furthermore, the lyophilizates obtained in the above examples were essentially amorphous, and ASA is unstable in its amorphous form.

[0082] [Example 11] Extensive formulation screening studies were conducted to co-lyophilize ASA with various basifying agents, preferably arginine, lysine, and Tris, to produce lyophilizates that could be reconstituted with water to a clear solution with a pH of about 6 or higher. These studies indicated that the stability of the bulk solution was insufficient to scale up the process. Furthermore, the solid-state stability of these lyophilizates was too low to produce a commercially viable product. Furthermore, sufficient amounts of water-soluble basifying agent could not be incorporated into the 80% TBA / 20% water bulk solution for lyophilization to achieve a final pH of greater than 6 for the reconstituted solution lyophilized product.

[0083] The only other approach remaining is to lyophilize ASA "as is" in a TBA / water solvent system (free acid form) without adding any basifying agent. This approach produces a lyophilizate of pure ASA that is inherently acidic and insoluble in water upon reconstitution. Therefore, the lyophilizate requires a special diluent for reconstitution that can neutralize the acidic ASA and produce a clear solution with a final pH of 6 or higher.

[0084] Based on these considerations, two lyophilized batches were prepared by dissolving aspirin in an 80% TBA / 20% water (v / v) solvent system to a concentration of 20 mg / ml. 5 ml aliquots were transferred to 10 cc vials and lyophilized. The batch sizes were 90 ml for the first batch (Example 11A, manufactured May 31, 2013) and 220 ml for the second batch (Example 11B, manufactured September 3, 2013). The solid-state stability of these two batches was evaluated at various temperatures. The stability data are summarized in Table 8.

[0085] [Table 10]

[0086] As shown in the table above, a very stable product was obtained with only minor loss of potency observed over a 6 month storage period at 40° C. It is rare for a lyophilized product to show no loss of potency under these accelerated conditions.

[0087] Since lyophilization of pure ASA resulted in a stable lyophilizate, the lyophilization cycle was optimized and the final lyophilization conditions are shown in Table 9.

[0088] [Table 11]

[0089] [Example 12] After optimizing the lyophilization cycle, two lyophilized batches were prepared by dissolving aspirin in an 80% TBA / 20% water (v / v) solvent system to a concentration of 20 mg / ml. Five-ml aliquots were transferred into 10 cc vials and lyophilized. The batch sizes were 1000 ml for the first batch (Example 12A) and 900 ml for the second batch (Example 12B). The solid-state stability of these two batches was evaluated at various temperatures. The stability data are summarized in Table 10. For batch 12A, stability studies were conducted at 40°C for up to 6 months, and at 30°C and 25°C for 9 months. For batch 12B, stability studies were conducted at 40°C for up to 6 months, at 30°C for up to 12 months, and at 25°C for up to 2 years. Both batches demonstrated excellent stability. For Batch 12B, after 24 months of storage at 25°C, the salicylic acid content increased from 0.1% to 0.48%, with only a 1.4% loss in potency. No other degradant peaks above the method's limit of quantitation were observed. Even after 40°C / 6 months of storage, no degradation was observed under accelerated conditions, and there was no cake shrinkage. It was quite unusual and unexpected for a lyophilized product to exhibit exceptional stability at 40°C / 6 months of storage. The data clearly demonstrate that the lyophilization process, in which ASA is predominantly present in its non-ionized form, surprisingly and unexpectedly results in a highly stable ASA product. The stability data are shown in Table 10.

[0090] [Table 12]

[0091] [Example 13] One aspect of this invention was to produce a stable lyophilized product and solvent system with sufficient bulk solution stability to withstand aseptic processing and lyophilization processes. The lyophilized products produced in the majority of these studies were made with an 80% TBA / 20%-60% TBA / 40% water solvent system, and the bulk solution for lyophilization was stable for 24 hours with minimal degradation. This goal was achieved. A second aspect of this invention was to identify a diluent suitable for reconstituting the lyophilized product to a concentration of ASA between about 20 mg / ml and about 100 mg / ml. The diluent criteria were that the neutralizing agent be acceptable and widely used in injectable formulations, and the pH of the reconstituted solution should be between pH 5.5 and 7.4 (close to physiological pH) with a target concentration of 20 to 100 mg ASA / ml. Using these boundary conditions, various organic and inorganic basifying agents were screened in diluents for reconstituting the ASA lyophilized product. Reconstitution studies were performed by reconstituting 100 mg vials with 5 ml of solution containing a buffer or a basifying agent or a combination of both. All basifying agents tested are listed in Table 11.

[0092] [Table 13]

[0093] The basifying agent is not limited to those tested. Basic oxides, hydroxides, and any inorganic alkali and alkali metal salts can be used. Similarly, organic bases with a pKa greater than 8.5 may be used to reconstitute aspirin lyophilizates. The amount of basifying agent required to completely dissolve the aspirin and bring the solution pH to about 6.0 can be determined by titrating a 20 mg / ml to 100 mg / ml aspirin slurry with the basifying agent.

[0094] [Example 14] The solubility of ASA is greater than 100 mg / ml at pH 5.5 and above. In the next step of the present invention, the amount of base required to obtain various concentrations of ASA solutions was determined. Tests were conducted using various concentrations of dibasic sodium phosphate to obtain various concentrations of aspirin up to 100 mg / ml. The data are shown in Table 12.

[0095] [Table 14]

[0096] It should be noted that as the concentration of ASA increases, the concentration of basifying agent to neutralize the ASA solution increases proportionally. Titration data for other amino acids can be obtained similarly.

[0097] [Example 15] All reconstituted solutions shown in Examples 13 and 14 exhibited slight turbidity. The presence of turbidity was independent of concentration. However, when ASA API was reconstituted under identical conditions, the resulting solutions exhibited no turbidity at all. Several tests were performed, but the origin of the turbidity could not be identified. When the reconstituted solutions were filtered through a 0.2 μm filter, the turbidity disappeared. However, the concentration of ASA before and after filtration did not change, suggesting that the turbidity was inherently present in the lyophilized product. When reconstituted with a basifying agent containing 0.01% or 0.05% polysorbate 80, the turbidity disappeared. The turbidity is likely due to the presence of residual TBA in the lyophilized product. Therefore, the diluent or solution for reconstitution contains 0.01% to 0.05% polysorbate 80.

[0098] Because aspirin products are administered via the IV bolus route, the isotonicity of the final reconstituted solution is an important factor in avoiding pain at the injection site. Therefore, lyophilizates containing 500 mg per vial were reconstituted with selected diluents to various concentrations, and their isotonicity was measured. The data are shown in Table 13.

[0099] [Table 15]

[0100] As shown in the table, the osmolality value of the 50 mg / ml ASA solution is higher compared to the 25 mg / ml solution. Phosphate buffer is not expected to be an ideal basifying agent due to the high isotonicity of the reconstituted solution. Based on these data, Tris or lysine, or a combination of Tris and lysine, are expected to be ideal basifying agents that can be included in the diluent to reconstitute the ASA lyophilizate.

[0101] IV irritation tests were performed by injecting ASA solutions of various osmolalities (300-1300 mOsm / kg) into the ear vein of rabbits. Surprisingly, no irritation was observed even with solutions of osmolality as high as 1300. This is an unexpected finding or observation.

[0102] [Example 16] The next step in development was to ensure that the selected buffer system not only resulted in a clear, colorless solution, but also provided sufficient solution stability. Lyophilized vials of 1 g strength were employed and reconstituted with the appropriate amount of buffer solution to achieve ASA concentrations of 25, 50, and 100 mg / ml. The pH and isotonicity values ​​of the final reconstituted solutions were measured. Solution stability testing was performed over an 8-hour period. The data are shown in Table 14.

[0103] [Table 16]

[0104] As shown in the table, the isotonicity values ​​of the higher concentration ASA solutions were high. For solutions reconstituted to concentrations of 25 and 50 mg / ml, a loss of approximately 6% potency occurred over 8 hours. After the 8-hour storage period, all reconstituted solutions were clear, except for 16F, for which the vial was reconstituted with buffer only, without polysorbate 80. The solution was cloudy and remained cloudy after 8 hours.

[0105] [Example 17] Stability data for two batches of lyophilizates are presented in Example 12. The exceptional stability of these two batches and two other previous pilot batches may be due to the formation of a solvate of ASA with TBA or the formation of crystalline ASA lyophilizates. All lyophilizates contained residual TBA in the range of 1000 to 3000 ppm. Differential scanning calorimetry (Perkin-Elmer, Model No. DSC4000) analysis of these samples showed distinct melting endotherms, suggesting that the drug may exist in a crystalline form. Lyophilization studies of ASA bulk solutions at various concentrations of aspirin, i.e., 25 mg / ml, 50 mg / ml, and 100 mg / ml, were performed to determine whether the concentration of aspirin in the bulk solution affected stability. All of these batches demonstrated excellent chemical stability. No loss of potency was observed in any of these batches over a 6-month storage period at 40°C. These data suggest that the stability of the ASA lyophilizates is independent of the aspirin concentration in the bulk solution. The thermal analysis data are shown in Table 15.

[0106] [Table 17]

[0107] As shown in the table, the melting points and enthalpies of fusion (Δ) of lyophilized aspirin made at various concentrations using either TBA / water or ethanol / water were fus H) is different from the API. The melting point and enthalpy of the lyophilized product are low and high. The enthalpy of the lyophilized product increased with increasing concentration of ASA in the bulk solution. The low melting point and high enthalpy of the lyophilized ASA suggest that a new crystalline form or crystalline substance for the ASA API may be formed during lyophilization. Further investigations were conducted to understand the crystallinity or crystal habit of the lyophilized aspirin product.

[0108] Additionally, particle size distributions of the lyophilizates and API were measured. Particle size measurements (Malvern, Mastersizer 2000) were performed on all samples using the dry powder volume distribution method. The data are presented in Table 14. As shown in the table, the particle size distributions of the lyophilized products made with various concentrations of aspirin in the TBA / water solvent system were significantly smaller than those of the API used to manufacture these batches. For example, the mean particle size of the 10% particles for the API was approximately 11.4 μm, while the particle size of the lyophilized product made with a 100 mg / ml aspirin concentration was 1.4 μm. This was a 10-fold reduction in particle size. Similar trends were observed for D50%, D90%, and D100%. Furthermore, the particle size of the lyophilized products decreased with increasing aspirin concentration in the bulk solution.

[0109] [Table 18]

[0110] [Example 18] Because the thermal data for the lyophilized product differed significantly from those of the API used to prepare the lyophilized product, and the presence of a distinct melting endotherm, it is suggested that lyophilization of ASA in a TBA / water solvent system may result in crystalline material in the vial. Lyophilized samples made at aspirin concentrations of 50 and 100 mg / ml in TBA / water and at 50 mg / ml in an ethanol / water system were submitted for X-ray analysis. The X-ray (Burker AXS) diffraction patterns for these samples are shown in Figures 1a–1d. As shown in the figures, the X-ray diffraction patterns clearly demonstrate that lyophilization of ASA in a TBA / water solvent system results in crystalline material, which is similar to the crystallinity of the API.

[0111] [Example 19] In Example 17, lyophilizates prepared with various concentrations of ASA in 80% TBA / 20% water were evaluated. X-ray analysis data suggested that crystalline material was consistently obtained during the lyophilization process, regardless of the ASA concentration in the bulk solution for lyophilization. The X-ray diffraction patterns of all these lyophilizates were similar. In the next part of this invention, the effect of various concentrations of TBA in the bulk solution for lyophilization was evaluated, with a constant ASA concentration of 100 mg / ml during the lyophilization process. Lyophilizates made from pure TBA in a 70:30 TBA:water system (Examples 19A-19E below) were tested. All lyophilizates were essentially crystalline. The X-ray diffraction patterns were consistent with those observed in the previous examples. These data suggest that the lyophilization process is robust and consistently yields the same crystalline form of ASA, regardless of the concentration of ASA or TBA in the solvent system used for lyophilization. Not only does the present invention produce crystalline forms using conventional freeze-drying methods, but the crystalline lyophilisates thus formed are independent of either the ASA or TBA concentration in the solvent system used for freeze-drying. These findings are quite unique, and to the inventors' knowledge, no other molecules have been observed using TBA as a solvent for freeze-drying.

[0112] The solid state stability of these lyophilizates was evaluated and the stability data are shown in Table 16. As shown in the table, all lyophilizates showed excellent stability as already observed in previous batches.

[0113] When these lyophilizates were reconstituted with a special diluent to a concentration of 100 mg / ml ASA, they dissolved slowly. Reconstitution times varied from 3 to 5 minutes. During reconstitution, it was observed that vigorous shaking was necessary to break up the lyophilizates. This was attributed to the wettability of the cake. Therefore, to improve the porosity of the lyophilizates, a lyophilizate containing 10 mg / ml mannitol (Example 19F) was prepared. Due to the fairly high aqueous solubility of mannitol, during reconstitution, mannitol dissolved first, thereby providing a flow path for the diluent, wetting and dissolving the ASA. As expected, the reconstitution time improved from 3 to 5 minutes to approximately 3 minutes. The presence of mannitol did not adversely affect the stability of ASA.

[0114] [Table 19]

[0115] [Example 20] One aspect of our discovery was to obtain a robust freeze-drying process that could consistently produce crystalline ASA during freeze-drying, regardless of the concentrations of essential ingredients, e.g., TBA, water, and ASA. This aspect of the invention was successfully realized. A second important aspect of the invention is the production of a lyophilizate with a reconstitution time of less than one minute when reconstituted with a special diluent to an ASA concentration of 100 mg / ml. Because the intended use of this dosage form is to treat patients with acute coronary syndrome (ACS) requiring urgent medical intervention, rapid dissolution is crucial to the invention. As previously mentioned, a dense cake was obtained with the lyophilizate produced using 80:20 TBA:water as the bulk solution for freeze-drying. When reconstituted with the special diluent, the cake was not wet and required vigorous shaking. After 5 minutes of vigorous shaking, the lyophilizate was completely dissolved.

[0116] To develop a rapidly dissolving lyophilizate, it is necessary to improve the cake porosity and wettability. Cake porosity can be improved by reducing the solid content per mL of the bulk solution for lyophilization. For example, decreasing the solid content increases the porosity of the lyophilizate. Therefore, the ASA concentration in the bulk solution for lyophilization was reduced from 100 mg / mL to 50 mg / mL. The incorporation of a small amount of surfactant, such as polysorbate 80, improves cake wettability. To determine the effect of low concentrations of ASA and the presence of small amounts of surfactant, bulk solutions containing 80:20 TBA:WFI (-20A to -20D) were prepared with an ASA concentration of 50 mg / mL and various levels of polysorbate 80. When these lyophilizates were reconstituted with a special diluent, the reconstitution time for -20A, B, and C was approximately 5 minutes, and the reconstituted solutions were observed to be slightly turbid. However, the reconstitution time for -20D improved to 3 minutes, and the solution was clear. The solid state stability data for these lyophilisates are shown in Table 17. As shown in the table, the presence of polysorbate 80 does not affect the stability of ASA.

[0117] [Table 20]

[0118] [Example 21] Another aspect of the present invention is the production of lyophilizates with low levels of residual TBA and reconstitution times of less than one minute. In Example 19 (19B-19D), increasing the proportion of water in the bulk solution for lyophilization was observed to reduce the residual TBA content in the lyophilizate. In Example 20 (20A-20D), reducing the concentration of ASA in the bulk solution and incorporating a small amount of polysorbate 80 reduced the reconstitution time. To further fine-tune the lyophilized formulation, a 65:35 TBA:water, 50 mg / ml ASA, and 0.1 mg / ml polysorbate 80 bulk solution for lyophilization was used, and cake wettability was enhanced in the presence of various bulking agents, such as sucrose, lactose, and mannitol. In all three examples, lyophilizates with porous cakes were obtained, and reconstitution times were instantaneous. Due to the addition of special diluents, the contents of the vial instantly went into solution. Stability was limited for these formulations, and the stability is comparable to previous batches.

[0119] [Table 21]

[0120] [Example 21] To confirm our findings, selected batches of ASA were prepared and final lyophilized samples (500 mg / vial) were submitted to the University of Minnesota for D-ray analysis, DSC, and TGA.

[0121] [Table 22]

[0122] [Example 22] In this example, a) 2D X-ray diffraction (2D XRD) Additional tests were conducted using

[0123] The D8 Discover 2D X-ray microdiffractometer is equipped with a two-dimensional Vantec detector, a video camera / laser alignment system, and a CoKα X-ray radiation point source (λ = 1.79 Å) aligned with a graphite monochromator. It is also equipped with focal collimators of various sizes and x, y, and z sample stages. Powder samples were loaded into the sample holder for reflection mode, and an 800 μm collimator was used. Measurement frames were scanned at 20 / 10° 2θ / ω, respectively. An averaging integration algorithm was used to finally convert the area detector images into a one-dimensional intensity vs. 2θ data set. The two values ​​are for CoKα radiation (λ = 1.79 Å) and CuKα radiation (λ = 1.54 Å). b) Differential scanning calorimetry (DSC) A differential scanning calorimeter (Q2000, TA Instruments, New Castle, DE) equipped with a refrigerated cooling accessory was used. Dry nitrogen gas was purged at 50 mL / min. The instrument was calibrated with indium. Powder samples were weighed, filled into aluminum pans, and sealed. Samples were cooled from room temperature to -10°C, equilibrated for 1 minute, and heated to 160°C at 10°C / min. c) Thermogravimetric analysis (TGA) A thermogravimetric analyzer (Q50, TA Instruments, New Castle, Del.) was used. Dry nitrogen gas was purged at 50 mL / min during the measurement. The powder sample was packed into an aluminum pan. The sample was heated to 220°C at 10°C / min.

[0124] result thermal analysis The samples showed significant weight loss near the melting temperature. Therefore, aspirin likely melts by decomposition. The melting point of aspirin has been reported to be 135°C (pubchem.ncbi.nlm.nih.gov). The enthalpy of fusion of aspirin has been reported to be in the range of 162-172 J / g (webbook.nist.gov).

[0125] [Table 23]

[0126] The XRD pattern of the freeze-dried sample matches the XRD pattern of aspirin corresponding to the reference analysis pattern in the International Centre for Diffraction Data (ICDD) powder analysis file. 1. The melting point of aspirin is approximately 135°C, and all freeze-dried samples melt in the range of 136-140°C. Rho_11 exhibits a slightly higher melting temperature (144°C). 2. The melting enthalpy of the freeze-dried system is consistent with the literature, but melting enthalpy is not a reliable parameter. A weight loss of 10% (obtained by TGA) is observed at the melting point (obtained by DSC). Decomposition may occur at the melting temperature. 3. The freeze-dried system exhibits batch-to-batch consistency. 4. All systems exhibit crystalline behavior. See Figure 2.

Claims

1. A liquid aspirin-containing composition having long-term stability, comprising aspirin and a co-solvent containing an organic solvent and water, wherein the ratio of the organic solvent to the water is about 95 / 5 to 50 / 50.

2. 10. The liquid aspirin-containing composition of claim 1, wherein the organic solvent is an alcohol.

3. 3. The liquid aspirin-containing composition of claim 2, wherein the alcohol is selected from the group consisting of t-butyl alcohol (TBA), n-butanol, ethanol, and mixtures thereof.

4. 4. The liquid aspirin-containing composition of claim 3, wherein the alcohol is t-butyl alcohol.

5. 2. The liquid aspirin-containing composition of claim 1, wherein the ratio of alcohol to water is about 60:40 to about 80:20, preferably about 65:35 to about 75:

25.

6. 10. The liquid aspirin-containing composition of claim 1, wherein the concentration of aspirin in the composition is from about 25 mg / ml to about 115 mg / ml, preferably from about 45 mg / ml to about 75 mg / ml or about 50 mg / ml.

7. 10. The liquid aspirin-containing composition of claim 1, further comprising a surfactant, preferably in an amount of about 0.05 to about 0.5 mg / ml.

8. 8. The liquid aspirin-containing composition of claim 7, wherein the surfactant is polysorbate 80 or Tween 80.

9. 10. The liquid aspirin-containing composition of claim 1, further comprising a solubility enhancer, preferably in an amount of about 2 to about 30 mg / ml, preferably about 5 to about 20 mg / ml.

10. 10. The liquid aspirin-containing composition of claim 9, wherein the solubility enhancer is sucrose or a sugar alcohol, preferably mannitol.

11. 10. The liquid aspirin-containing composition of claim 1, further comprising a buffering agent preferably selected from the group consisting of Tris, glycine or other amino bases with a pKa above 8.

12. 2. The liquid aspirin-containing composition of claim 1, wherein the amount of aspirin decomposed to salicylic acid after 24 hours at ambient temperature is ≦about 2%, preferably ≦about 1.5% or ≦about 1.0%.

13. 10. The liquid aspirin-containing composition of claim 1, wherein the co-solvent is a mixture comprising TBA and water in a ratio of about 65:35 to about 75:25, the aspirin is present in an amount of about 45 to about 75 mg / ml, and further comprises about 0.05 to about 0.5 mg / ml polysorbate 80 and about 5 to about 25 mg / ml mannitol.

14. 2. The liquid aspirin-containing composition of claim 1, wherein the co-solvent comprising an organic solvent and water is selected from the group consisting of TBA / water, n-butanol / water, ethanol / water, PEG-ethanol / water, DMSO / water, DMF / water, and PEG / n-butanol / water.

15. 10. Use of the liquid aspirin-containing composition of claim 1 as a bulk solution for producing lyophilized aspirin.

16. 10. A method of producing freeze-dried aspirin, comprising providing a liquid aspirin-containing composition according to claim 1, freeze-drying the composition, and recovering the resulting freeze-dried aspirin.

17. 17. The method of claim 16, wherein the liquid aspirin-containing composition contains about 20 to about 100 mg / ml aspirin, and the co-solvent comprises t-butyl alcohol and water, wherein the ratio of t-butyl alcohol to water is about 80:20 to about 60:40, preferably about 65:

35.

18. 17. The method of claim 16, wherein the lyophilized aspirin is crystalline.

19. 19. The method of claim 18, wherein the crystalline aspirin has a melting point in the range of 136°C to 144°C as determined by differential scanning calorimetry or DSC.

20. 17. A lyophilized aspirin produced by the method of claim 16.

21. 21. The lyophilized aspirin of claim 20, having a shelf life of at least 2 years under ambient storage conditions.

22. 21. The freeze-dried aspirin of claim 20, having less than about 2.0% total degradants after 2 years at 25°C, preferably less than about 1.5% or 1.0% by weight salicylic acid after 2 years at 25°C.

23. 21. The freeze-dried aspirin of claim 20, wherein the amount of residual t-butyl alcohol in the freeze-dried aspirin is less than about 0.5%, preferably about 500 to about 10,000 ppm or about 1,000 to about 3,000 ppm.

24. Aspirin was lyophilized from a bulk solution having a concentration of about 50, 75, or 100 mg / ml, and the lyophilized aspirin made at each concentration was lyophilized to the following: 【Table 1】 21. The lyophilized aspirin of claim 20, having a particle size distribution of

25. A kit for aspirin therapy comprising a first container containing a therapeutic amount of lyophilized aspirin and a second container containing water and a basifying agent.

26. 26. The kit of claim 25, wherein the second container further comprises a surfactant, preferably at a concentration of about 0.01 to about 0.4 mg / ml, preferably about 0.2 mg / ml.

27. 26. The kit of claim 25, wherein the surfactant is polysorbate 80.

28. 26. The kit of claim 25, wherein the basifying agent is selected from the group consisting of amino acids, organic bases, and inorganic bases, or basic salts of alkali and alkaline metals.

29. 29. The kit of claim 28, wherein the amino acid or organic base has a pKa of 8.5 or greater.

30. 29. The kit of claim 28, wherein the amino acid is selected from the group consisting of arginine, lysine, and glycine.

31. 29. The kit of claim 28, wherein the organic base is Tris.

32. 29. The kit of claim 28, wherein the inorganic base or salt form is selected from the group consisting of sodium carbonate, sodium bicarbonate, and dibasic sodium phosphate.

33. 26. The kit of claim 25, wherein the amount of basifying agent is sufficient to provide a solution, upon combining the contents of the first and second containers, at a pH of at least about 5.5, preferably about 6.0, more preferably about 6.0 to about 7.4, or at about or near physiological pH.

34. 26. An intravenous liquid aspirin-containing composition prepared by combining the contents of the first and second containers of the kit of claim 25.

35. 35. The intravenous liquid aspirin-containing composition of claim 34, wherein the composition has an isotonicity of about 270 to about 1300 mOsm / kg.

36. 35. The intravenous liquid aspirin-containing composition of claim 34, comprising about 20 to about 140 mg / ml, preferably about 100 mg / ml, of aspirin, a sugar alcohol, preferably mannitol, and a surfactant, said composition having less than about 0.1% TBA in the composition.

37. 38. A method of providing aspirin therapy comprising intravenously administering an effective amount of the intravenous liquid aspirin-containing composition of claim 34 to a mammal in need thereof.

38. 38. The method of claim 37, wherein the amount of aspirin administered intravenously is from about 80 to about 1200 mg, preferably from about 300 to about 1000 mg.

39. 38. The method of claim 37, wherein the aspirin concentration of the intravenously administered composition is from about 20 to about 50 mg / ml.

40. 38. The method of claim 37, wherein the amount of intravenous aspirin-containing composition administered is from about 1 ml to about 10 ml.

41. 38. The method of claim 37, wherein the intravenous aspirin-containing composition is administered intravenously over a period of not more than about 90 seconds, preferably over a period of about 60 seconds.

42. 38. The method of claim 37, wherein the mammal is a human.

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