Liquid, multi-dose, ready-to-use warfarin composition and use

Abstract

The present invention relates to a liquid, multi-dose, ready-to-use pharmaceutical composition comprising: a) warfarin or a pharmaceutically acceptable salt thereof, b) an excipient that is both an antioxidant and pH regulator, and c) a fluid; wherein the composition has a pH of 8.0 – 11.0. The invention further provides a method of manufacturing said pharmaceutical warfarin composition and provides uses of the pharmaceutical warfarin composition.

Description

[0001] LIQUID, MULTI-DOSE, READY-TO-USE WARFARIN COMPOSITION AND USE

[0002] TECHNICAL FIELD

[0003] The present invention is situated in the field of pharmaceutical compositions and medical uses of pharmaceutical compositions. The invention is advantageous as it provides liquid, multi-dose, ready-to-use warfarin compositions, with adequate warfarin solubility and storage stability. The warfarin solution according to the invention is particularly suitable for use in pediatric or geriatric patients who have problem swallowing. The warfarin solution according to the invention is also suitable for use in a warfarin-responsive treatment where accurate dose titration is required.

[0004] BACKGROUND

[0005] Warfarin is a well-known pharmaceutical active ingredient. It is commonly used in salt form such as warfarin sodium or potassium. Warfarin sodium has a molecular weight of 360.37 g / mol.

[0006] Warfarin sodium is known by its chemical name as 4-hydroxy-3-(3-oxo— 1-phenylbutyl)-2H-l-benzopyran-2-one sodium salt. Its chemical structure is represented by Formula I:

[0007]

[0008] O

[0009] Formula I

[0010] Warfarin sodium is a well-established, widely used anticoagulant that acts by blocking the synthesis of vitamin K-dependent coagulation factors (II, VII, IX and X). Medical conditions for which warfarin sodium is prescribed include venous thrombosis, pulmonary embolism, myocardial infarction, progressive stroke. Currently, warfarin sodium is only commercially available for oral administration in tablet form in the US and in tablet and suspension form outside of the US. Even warfarin sodium products available for intravenous injection are not provided in liquid form but as a lyophilized powder for reconstitution with sterile water before administration by injection. An example is Coumadin®, commercially available by Bristol-Myers Squibb, which is a warfarin sodium provided as a lyophilized powder. The powder requires reconstitution by sterile water for intravenous injection. The liquid prepared must be used within 4 hours from preparation as the warfarin sodium formulation is chemically and physically stable for only 4 hours at room temperature. After reconstitution, the warfarin sodium formulation must be stored at controlled room temperature between 15 - 30°C, and any unused solution must be discarded.

[0011] WO2006 / 138534 from Morton Grove Pharmaceuticals discloses a stable warfarin sodium liquid formulation comprising at least 20% (v / v) glycerin, an alcohol such as ethanol, a phosphate buffer to buffer the pH, and 0.1 - 20 mg / ml warfarin sodium as active pharmaceutical ingredient. The warfarin sodium liquid formulation has a pH above 5, preferably pH 8-9. After 1 month at room temperature the assay content has degraded by 5% or less. Glycerin is described as essential for the formulation as it helps inhibit reprecipitation of warfarin out of the solution in buffer. In addition, it is disclosed to impart a sweet taste and glycerin may act as an antimicrobial or antibacterial agent. However, some known side effects of glycerin are diarrhea, dizziness and dryness of mouth or increased thirst. Glass and plastic bottles are provided as suitable packaging. Brown color glass was preferred over clear glass containers as warfarin sodium is sensitive to light. However, it is known that phosphate buffer is incompatible with glass and that particles are formed.

[0012] Ogawa et al. (Chem. Pharm. Bull. 61(5), 539-545, 2013) reported on the generation of inorganic particles generated in glass vials filled with phosphate buffer solutions. The generation of particles accelerated at higher storage temperatures. Hence, it is desirable to find an alternative as warfarin is very sensitive to particle formation.

[0013] Rosemont Pharmaceuticals Ltd commercializes a warfarin sodium 1 mg / ml oral suspension in Europe (Product Leaflet, Nov 2021 revision). Other ingredients are propylene glycol, benzoic acid, xanthan gum, polysorbate 90, citric acid, disodium phosphate, aluminum magnesium silicate, liquid maltitol, masking flavor and purified water. The warfarin sodium suspension is white to off-white. It is packaged in a brown glass bottle holding 150 ml of suspension. The bottle comes in a kit together with a 10 ml purple syringe and an adaptor. The product leaflet advises that after opening the bottle the suspension can only be used for 1 month. It is also recommended not to store the medicine above 25°C.

[0014] Dimitrokalli et al. (Molecules, Nov 26(21), 6631-6645, 2021) investigated the commercially available low dose warfarin sodium suspension of Rosemont Pharmaceuticals Ltd. They reported the formulation having a pH close to 5.5 and the formation of precipitates in the form of needle shaped crystals.

[0015] Schlatter and Cisternino (Eur J Hosp Pharm 25, 98-101, 2018) reported on the stability of warfarin sodium flavored preservative-free oral liquid formulations prepared from either warfarin sodium clathrate pure powder or tablets. The powder or tablets were dispersed in a mixture containing deionized water, glycerin, sodium phosphate and strawberry alcohol-free concentrate flavor. pH of the formulations was 8.63 (powder) and 8.12 (tablets) respectively. The formulations were stored in amber glass bottles at 25 °C and 4°C. Due to the absence of preservative, the maximum expiry date was 1 month. pH of the formulations decreased by 1.4 and 1.16 pH units respectively when stored at 25°C for 90 days. Also, the assay content of the formulations showed a decline during the study period.

[0016] In view of the above, there remains a need in the art for liquid, multi-dose, ready-to-use warfarin solutions.

[0017] The objective of the present invention is to solve at least one or more problems as described above. In particular, the invention aims to provide a warfarin solution with adequate warfarin solubility and storage stability (active ingredient content, impurity profile, cold and warm conditions, microbial growth suppression). The invention aims to provide a palatable warfarin solution.

[0018] SUMMARY OF THE INVENTION

[0019] In a first aspect, the invention provides a liquid, multi-dose, ready-to-use, pharmaceutical composition comprising:

[0020] a) warfarin or a salt thereof, b) an excipient that is both an antioxidant and pH regulator, and

[0021] c) a fluid;

[0022] wherein the composition has a pH of 8.0 - 11.0.

[0023] Preferably, b) the excipient that is both an antioxidant and pH regulator, is sodium sulphite.

[0024] In a preferred embodiment sodium sulphite is present in an amount of 2 mg / ml to 10 mg / ml of the pharmaceutical composition.

[0025] In another preferred embodiment, b) the excipient that is both an antioxidant and pH regulator, is arginine.

[0026] In a preferred embodiment arginine is present in an amount of 2 mg / ml to 50 mg / ml of the pharmaceutical composition according to an embodiment of the invention, preferably in an amount of 5 mg / ml to 35 mg / ml, more preferably in an amount of 10 to 30 mg / ml, most preferred the amount of arginine in the pharmaceutical composition is 10 mg / ml.

[0027] In a preferred embodiment, the pharmaceutical composition has a pH of 9.1 -10.7.

[0028] Preferably, the composition when stored for three months in a sealed, sterile container at 25°C / 60% RH and 40°C / 25% RH contains no more than 1.0% total impurity as measured by HPLC.

[0029] In a preferred embodiment the pharmaceutical composition is in the form of an oral solution, more preferably a palatable oral solution.

[0030] In a preferred embodiment c) the fluid is selected from an aqueous solution, propylene glycol (PG) or combinations thereof.

[0031] In a preferred embodiment glycerin and parabens are excluded from a pharmaceutical composition according to an embodiment of the invention. In a preferred embodiment a buffer agent is excluded from a pharmaceutical composition according to an embodiment of the invention. Preferably sodium phosphate buffer is excluded.

[0032] In a preferred embodiment the pharmaceutical composition according to the invention comprises warfarin sodium, warfarin potassium, warfarin clathrate or a combination thereof.

[0033] Preferably warfarin sodium is present in an amount of 0.1 to 20 mg / ml; more preferably 0.2 to 10 mg / ml; even more preferably 0.5 to 5 mg / ml; most preferably 1 mg / ml.

[0034] In a preferred embodiment the pharmaceutical composition according to the invention further comprises e) a preservative in a suitable concentration for protection of the composition against bacterial growth. Preferably the preservative is ethanol.

[0035] In a preferred embodiment the pharmaceutical composition according to the invention has a cold storage stability of at least 3 months as measured at 2°C-8°C.

[0036] In a preferred embodiment the pharmaceutical composition according to the invention comprises a sweetener, preferably sucralose.

[0037] In a preferred embodiment the pharmaceutical composition according to the invention comprises a sweetener in an amount of 0.1 to 20 mg / ml.

[0038] In a further aspect, the invention provides use of a pharmaceutical composition according to an embodiment of the invention as a medicine.

[0039] Preferably the pharmaceutical composition is for use in the treatment of venous thrombosis, pulmonary embolism, thromboembolic complications associated with atrial fibrillation and / or cardiac valve replacement, in the reduction in the risk of death, recurrent myocardial infarction, thromboembolic events, such as stroke or systemic embolization, after myocardial infarction. In a preferred embodiment the pharmaceutical composition according to an embodiment of the invention, is used for the treatment of a pediatric or geriatric patient or a patient having difficulties swallowing.

[0040] In a further aspect, the invention provides a kit comprising at least one pharmaceutically acceptable container containing one or more doses of the pharmaceutical composition according to an embodiment of the invention in combination with instructions for storage and use of the kit.

[0041] In a final aspect, the invention provides a method of producing a pharmaceutical composition, preferably according to an embodiment of the invention, comprising the steps of: dissolving sodium sulphite or arginine in water in an amount sufficient to obtain a solution of pH 8-10, adding warfarin or a pharmaceutically acceptable salt to said aqueous sodium sulphite or arginine solution and adding propylene glycol, thereby obtaining the pharmaceutical composition.

[0042] DETAILED DESCRIPTION OF THE INVENTION

[0043] Unless otherwise defined, all terms used in the description of the invention, including technical and scientific terms, have the meaning as commonly understood by a person skilled in the art to which the invention pertains. Furthermore, definitions of the terms are included to better understand the description of the present invention.

[0044] As used here, the following terms have the following meaning: "A", "an", and "the" as used here refer to both the singular and the plural, unless the context indicates otherwise. "A surfactant" refers, by way of example, to one or more than one surfactant.

[0045] "About" as used herein, referring to a measurable value such as a parameter, an amount, a duration and the like, is intended to include variations of plus or minus 10% or less, preferably plus or minus 5% or less, more preferably plus or minus 3% or less, even more preferably plus or minus 1% or less, and even more preferably plus or minus 0.1% or less of the specified value, as far as such variations are suitable for carrying out in the described invention. It will be clear, however, that the value to which the term "about" relates is itself also specifically described. "Include", "comprising" and "comprises" is used herein are synonymous with "contain", "containing" or "contains" and are inclusive or open terms that specify the presence of what follows, e.g. a component and the presence of additional, unnamed components, features, elements, parts, steps, which are well known in the art or described therein, and do not exclude them.

[0046] The recitation of numerical ranges by endpoints includes all numbers and fractions that are included within that range, as well as the endpoints mentioned.

[0047] The term "% w / w" as used herein means percentage by weight in which the weight ratio of an ingredient to the total weight of a composition is expressed as a percentage.

[0048] In a first aspect, the present invention provides a liquid, multi-dose, ready-to-use, pharmaceutical composition comprising:

[0049] a) warfarin or a salt thereof,

[0050] b) an excipient that is both an antioxidant and pH regulator, and

[0051] c) a fluid;

[0052] wherein the composition has a pH of 8.0 - 11.0.

[0053] In a preferred embodiment b) the pharmaceutical excipient that acts both as an antioxidant and pH regulator is sodium sulphite.

[0054] In another preferred embodiment b) the pharmaceutical excipient that acts both as an antioxidant and pH regulator is arginine.

[0055] In a preferred embodiment, the present invention provides a liquid, multi-dose, ready-to-use pharmaceutical composition comprising

[0056] a) warfarin or a salt thereof,

[0057] b) an antioxidant,

[0058] c) a pH regulator, and

[0059] d) a fluid;

[0060] wherein the b) antioxidant and c) pH regulator is sodium sulphite or arginine; and wherein the composition has a pH between 8.0 - 11.0. In a preferred embodiment, the pharmaceutical composition comprises warfarin sodium, warfarin potassium, warfarin clathrate or a combination thereof.

[0061] In a preferred embodiment, warfarin sodium is present in an amount of 0.1 to 20 mg / ml; more preferably 0.2 to 10 mg / ml; even more preferably 0.5 to 5 mg / ml; most preferably around 1 mg / ml of the pharmaceutical composition.

[0062] In a preferred embodiment, sodium sulphite is present in an amount of 2 mg / ml to 10 mg / ml of the pharmaceutical composition. More preferably 3 mg / ml to 7 mg / ml sodium sulphite is present. Even more preferably, 4 to 6 mg / ml. Most preferably around 5 mg / ml sodium sulphite is present.

[0063] In another preferred embodiment, arginine is present in an amount of 2 mg / ml to 50 mg / ml of the pharmaceutical composition, preferably 5 mg / ml to 35 mg / ml of arginine is present, more preferably 10 to 30 mg / ml, most preferred the amount of arginine in the pharmaceutical composition is 10 mg / ml.

[0064] In a preferred embodiment, the pharmaceutical composition has a pH of 9.1 -10.7.

[0065] In a preferred embodiment, buffer agents such as phosphate buffers are excluded from the pharmaceutical composition. Surprisingly, a stable warfarin oral solution composition is obtained without using any buffer agent or buffer excipient.

[0066] In a preferred embodiment, EDTA and Vitamin E TPGS are excluded from the pharmaceutical composition. Surprisingly, a stable warfarin oral solution is obtained without using EDTA and Vitamin E TPGS as antioxidants.

[0067] In a preferred embodiment, the composition when stored for three months in a sealed, sterile container at 25°C / 60% RH and 40°C / 25% RH contains no more than 1.0% total impurity as measured by HPLC (long term storage stability).

[0068] In a preferred embodiment, the pharmaceutical composition is in the form of an oral solution, preferably a palatable oral solution. In a preferred embodiment, c) the fluid is selected from an aqueous solution, propylene glycol (PG) or combinations thereof.

[0069] In a preferred embodiment, the pharmaceutical composition comprises 300 to 900 mg / ml propylene glycol, preferably 400 to 800 mg / ml propylene glycol, even more preferably 500 to 700 mg / ml propylene glycol.

[0070] In another preferred embodiment, the pharmaceutical composition comprises 400 to 500 mg / ml of propylene glycol.

[0071] In a preferred embodiment, glycerin and parabens are excluded from the pharmaceutical composition. Surprisingly, this combination was found to be incompatible at high temperatures and high pH.

[0072] In a preferred embodiment, the pharmaceutical composition further comprises a viscosity enhancer; preferably the viscosity enhancer is hydroxypropyl methyl cellulose (HPMC).

[0073] In a preferred embodiment, the pharmaceutical composition comprises 1 to 100 mg / ml viscosity enhancer, more preferably 10 to 50 mg / ml viscosity enhancer.

[0074] In a preferred embodiment, the pharmaceutical composition further comprises a preservative in a suitable concentration for protection of the composition against bacterial growth; preferably the preservative is ethanol.

[0075] More preferably the pharmaceutical composition comprises between 10 and 100 mg / ml of ethanol. Even more preferably the pharmaceutical composition comprises between 20 and 90 mg / ml ethanol. Most preferably the pharmaceutical composition comprises 40 to 60 mg / ml ethanol. The addition of ethanol was found useful for the suppression of bacterial growth and for cold storage stability of a composition according to an embodiment of the invention.

[0076] In another preferred embodiment, the pharmaceutical composition comprises 1 to

[0077]

[0078] In a preferred embodiment, the pharmaceutical composition has a cold storage stability of at least 3 months as measured at 2°C-8°C. More preferably cold storage stability at 2°C-8°C (refrigerator conditions) is at least 4 months; even more preferably at least 5 months; most preferably at least 6 months. A composition with cold storage stability displays an absence of crystal growth and absence of deposits. These can be observed and measured by light microscopy.

[0079] In a preferred embodiment, the pharmaceutical composition, further comprises a sweetener. Preferably the sweetener is sucralose.

[0080] Preferably the sweetener is present in an amount of 0.1 to 20 mg / ml; more preferably in an amount of 0.2 to 15 mg / ml sweetener; most preferably in an amount of 0.3 to 10 mg / ml sweetener.

[0081] In a preferred embodiment, the pharmaceutical composition, further comprises a flavoring agent. Preferably, the flavoring agent is selected from lemon, orange, blood orange, peach, cinnamon, black current, cherry, mint, vanilla, banana, apple, pear, strawberry, raspberry, lime, butterscotch, caramel, cinnamon, chocolate and mixtures thereof. More preferably the flavoring agent is blood orange, peppermint or cherry.

[0082] In a preferred embodiment, the amount of flavoring agent is 0.1 to 10 mg / mL, preferably 0.5 to 5 mg / mL, more preferably 1 to 4 mg / mL.

[0083] In a further aspect, the invention provides a pharmaceutical composition as previously disclosed for use as a medicine.

[0084] The pharmaceutical composition according to an embodiment of the invention, for use in the treatment of venous thrombosis, pulmonary embolism, thromboembolic complications associated with atrial fibrillation and / or cardiac valve replacement, in the reduction in the risk of death, recurrent myocardial infarction, thromboembolic events, such as stroke or systemic embolization, after myocardial infarction.

[0085] The pharmaceutical composition according to an embodiment of the invention, wherein the composition is used for the treatment of a pediatric or geriatric patient or a patient having difficulties swallowing. For instance, a patient recovering from a stroke.

[0086] In a preferred embodiment, the composition makes use of ingredients that regulatory agencies find acceptable (e.g. within the FDA's Inactive Ingredient Guide - IIG limits) to enable market introduction and patient availability.

[0087] In a preferred embodiment the pharmaceutical composition comprises:

[0088] a) 1.0 mg / ml warfarin sodium

[0089] b+c) 5.0 mg / ml sodium sulphite

[0090] d) 605.0 mg / ml propylene glycol

[0091] e) 5.0 mg / ml ethanol

[0092] f) 10.0 mg / ml sucralose

[0093] g) 30 mg / ml hydroxy propyl methylcellulose (HPMC)

[0094] h) remainder purified water.

[0095] In a preferred embodiment the pharmaceutical composition comprises:

[0096] a) 1.0 mg / ml warfarin sodium

[0097] b+c) 10.0 to 30.0 mg / ml mg / ml arginine

[0098] d) 400 to 500.0 mg / ml propylene glycol

[0099] e) 5.0 mg / ml ethanol

[0100] f) 10.0 mg / ml sucralose

[0101] g) 30.0 mg / ml hydroxy propyl methylcellulose (HPMC)

[0102] h) remainder purified water.

[0103] In a preferred embodiment the pharmaceutical composition comprises:

[0104] a) 1.0 mg / ml warfarin sodium

[0105] b+c) 10.0 mg / ml arginine

[0106] d) 400 to 500 mg / ml propylene glycol

[0107] e) 5.0 mg / ml ethanol

[0108] f) 10.0 mg / ml sucralose

[0109] g) 30 mg / ml hydroxy propyl methylcellulose (HPMC)

[0110] h) remainder purified water.

[0111] In a preferred embodiment the pharmaceutical composition comprises: a) 1.0 mg / ml warfarin sodium

[0112] b+c) 10.0 mg / ml arginine

[0113] d) 450 mg / ml propylene glycol

[0114] e) 5.0 mg / ml ethanol

[0115] f) 10.0 mg / ml sucralose

[0116] g) 30 mg / ml hydroxy propyl methylcellulose (HPMC)

[0117] h) remainder purified water.

[0118] In a further aspect, the invention provides a kit comprising at least one pharmaceutically acceptable container containing one or more doses of the pharmaceutical composition according to an embodiment of the invention in combination with instructions for storage and use of the kit.

[0119] In a preferred embodiment the pharmaceutically acceptable container is a glass bottle, preferably an amber color glass bottle, or a HDPE plastic bottle. Preferably the bottle has a packaging volume of 50 - 200 ml. More preferably the packaging volume is 75 - 150 ml. Most preferably the packaging volume is 100 ml.

[0120] In a preferred embodiment the kit according to an embodiment of the invention comprises an oral syringe; more preferably the oral syringe is a graded syringe. Even more preferably a 10 ml oral syringe is comprised in the kit. Most preferably a 10 ml oral syringe with graduations is comprise din the kit.

[0121] In an additional aspect, the invention provides a method of producing a pharmaceutical composition, preferably according to an embodiment of the invention, comprising the steps of:

[0122] dissolving sodium sulphite or arginine in water in an amount sufficient to obtain a solution of pH 8-10, adding warfarin or a pharmaceutically acceptable salt to said aqueous sodium sulphite or arginine solution and adding propylene glycol, thereby obtaining the pharmaceutical composition.

[0123] In a preferred embodiment, the method further comprises the step of adding hydroxy propyl methylcellulose (HPMC) to the solution. The addition of HPMC has the advantage that the viscosity of the solution may be adjusted to provide a pleasant mouthfeel. In a preferred embodiment, the method further comprises addition of a crystallization inhibitor, such as ethanol. Preferably ethanol is added in a concentration of 10 to 100 mg / ml.

[0124] In a preferred embodiment, the method further comprises addition of a flavor and / or sweetener. This is advantageous for providing a palatable oral solution. Especially for use in a pediatric population, this may be of importance for treatment adherence. In a preferred embodiment, the method further comprises the step of blanketing the solution with an inert gas, preferably nitrogen.

[0125] In a preferred embodiment, the method further comprises the step of providing low oxygen content water for the preparation of the pharmaceutical composition. Low oxygen content water may be obtained by bubbling nitrogen through the water. It may also be obtained by heating water to a temperature between 80°C and 99°C and upon cooling protecting the solution from re-uptake of oxygen, e.g. by blanketing with nitrogen or argon, or by applying pressure. Preferably the dissolved oxygen content is not more than 5%, more preferably not more than 1%, even more preferably not more than 0.5%, most preferably not more than 0.1%.

[0126] Most preferably the method of manufacturing the pharmaceutical warfarin solution comprises the steps of:

[0127] dispensing the required quantity of water in a mixing tank, purging the water with nitrogen to ensure a dissolved oxygen content of less than 5%, dissolving sodium sulfite or arginine in water, adding warfarin or a pharmaceutically acceptable salt to the aqueous sodium sulfite or arginine solution, preferably mixing for 10-15 minutes to obtain a clear solution, adding HPMC to the solution obtained in the first step, then adding propylene glycol, preferably stirring for 10-15 minutes to obtain a clear solution,

[0128] - adding ethanol to the solution obtained in the previous step,

[0129] adding a flavor and / or sweetener to the solution,

[0130] pouring the solution obtained with nitrogen or another inert gas such as argon to obtain a dissolved oxygen content of less than 5%, - filtering the solution through a 5 micrometer filter and filling it in bottles, preferably HDPE bottles,

[0131] purging nitrogen in the head space to remove oxygen from the head space,

[0132] closing the container with a cap.

[0133] In a final aspect, the invention provides a method for treating a warfarin responsive disease or condition comprising administering a pharmaceutical composition according to an embodiment of the invention to a patient in need thereof.

[0134] A warfarin oral solution according to an embodiment of the invention will facilitate the use of anticoagulation therapy in an elderly population or population with transient swallowing difficulties, minimize risks associated with inappropriate crushed or diluted drug dosage and provides easy administration and titration, creating an individualized dose based on Internal Normalized Ratio (INR) response.

[0135] Preferably the subject is a pediatric or geriatric patient or a patient having difficulties swallowing, such as a patient recovering from a stroke.

[0136] Preferably the patient is administered a dose of 2 to 10 mg warfarin, preferably in the form of a pharmaceutically acceptable salt. Most preferably the dose is administered once daily.

[0137] A warfarin oral solution according to an embodiment of the invention is preferably supplied in a 150 ml multi-dose container and supplied with an oral syringe. The container can be a glass container or plastic container. More preferably the glass container is an amber colored glass container. This provides additional protection against degradation by light. A preferable plastic container is a High-Density PolyEthylene (HDPE) container.

[0138] A warfarin oral solution according to an embodiment of the invention may be titrated based on INR response. Patients preferably take medication at home (selfadministration).

[0139] The invention is illustrated hereafter by the following non limiting examples. EXAMPLES

[0140] A. Physical form

[0141] Two forms of warfarin are available, namely an amorphous salt form (warfarin sodium, warfarin potassium) and a crystalline form (warfarin clathrate). Both commercially available forms were evaluated. Solid state X-ray diffraction analysis and differential scanning calorimetry were used as analytical methods to confirm the amorphous or crystalline form of the active ingredient.

[0142] B. Saturation solubility

[0143] A saturation solubility study was performed to study the behavior of both the amorphous and crystalline form of warfarin. Maximum solubility for both amorphous and crystalline warfarin were studied in different physiologically compatible conditions. Several samples were prepared that differed in solvent system, pH and ingredients. These samples either had warfarin sodium clathrate (crystalline) or warfarin sodium (amorphous) as active ingredient. The samples were stored in amber color glass vials. A physical observation was made, and the pH and solubility were measured. A solubility of less than 1 mg / ml was considered not to be soluble.

[0144] The results of the solubility and physical observations upon preparation of the samples, are provided in Table 1.

[0145] Based on the results summarized in Table 1, it was concluded that:

[0146] - The amorphous form of warfarin sodium was almost 13 times more soluble in purified water than the crystalline form (warfarin sodium clathrate).

[0147] - The crystalline form solubilized in water provides a pH near 8, while the amorphous form provides a pH near to 10. The crystalline form showed precipitation in water whereas the amorphous form did not show precipitation at pH close to 10.

[0148] - A similar result is obtained in a 0.01 M phosphate buffer - pH 8 medium. The solubility ratio of crystalline vs amorphous warfarin is about 1:14. Solubilization of warfarin sodium clathrate gave a pH of about 8.50, whereas solubilization of warfarin sodium provided a pH of about 9.3.

[0149] Both the amorphous and crystalline forms of warfarin had negligible solubility in buffer systems tested in the pH range of 1.2 to 7. It is concluded that none of these buffer systems can be used as a formulation vehicle as such, and are in need of a solubilization aid.

[0150] - Although solutions looked clear at visual appearance, particles / crystals were observed in all the samples when observed with light microscopy. Hence, the stability at actual targeted concentration needs to be verified.

[0151] - The highest solubility was found for both forms of warfarin using the following media: TRIS-HCI buffer- pH 7.5 purified water; purified water pH 5.5; purified water pH 6.5, and phosphate buffer pH 8. For these samples there was also a clear solution visual appearance at day 7.

[0152] From the results above it was concluded that the active ingredient should have good physical solution state stability in a solution with pH above 8, even better above pH 9.

[0153] As solubility itself is not an issue, but stability and avoiding precipitation are, an extensive excipient compatibility series of tests was conducted at room temperature and accelerated storage stability conditions.

[0154] C. Excipient compatibility

[0155] The samples for the excipient compatibility study were prepared by accurately weighing an excipient, adding it to purified water, recording the pH. Excipients were selected within different categories such as sweeteners, alkalizers, surfactants / solubilizers, vehicles / solvents, polymers, preservatives and buffers. Then the active ingredient was added. Each 1 ml of formulation contained 1 mg of warfarin sodium or 1 mg of warfarin sodium clathrate. The preparation was conducted under a sodium vapor lamp as the active ingredient is light sensitive. The pH was recorded after addition of the active ingredient too. Each sample was prepared in a volume of 300 ml. The samples prepared were filtered. Sample aliquots were filled in 10 ml amber color glass vials. The vials were closed with an airtight rubber cap and aluminum crimp to obtain closed conditions.

[0156] To study the precipitation potential of the samples, the samples were stored cold at 2°C-8°C and the samples were subjected to increased temperature in accelerated storage stability conditions (40°C / 75% Relative Humidity, 25°C / 60% Relative Humidity). The % transmittance was measured to confirm if there was crystal growth or precipitation of the active ingredient. Excipient-active ingredient compatibility was assessed through HPLC analysis of binary / combination mixtures of excipients and active ingredient in solution state. The maximum concentration of excipients was used in active ingredient: excipient compatibility samples considering worst case to observe the interaction.

[0157] Storage conditions: 2°C-8°C, 40°C / 75%RH, 25°C / 60% RH- closed condition Time Intervals: Initial, 2, 4 and 8 weeks

[0158] Tests: physical appearance, pH, % light transmittance, microscopy, and related substances.

[0159] The studied excipients were the following: cyclodextrin HPPCD, Kollidon K12PF, HPMC, Carboxy Methyl Cellulose, Kollidon VA64, Eudragit, Polyvinyl alcohol, Xanthan Gum, Hydroxyethyl cellulose, Hydroxypropylmethyl cellulose, Glycerin, Propylene Glycol, Polysorbate, Sodium Lauryl sulphate, Vitamin E TPGS, Poloxamer, Polyethylene glycol, Benzyl alcohol, Ethanol, Sucralose, Lycasin, Neotame, Sorbitol, Xylisorb, Mannitol, Meglumine, L-arginine, Sodium stearyl fumarate, Glycine, NaCI, Sodium Phosphate Dibasic Heptahydrate, Sodium Pyrophosphate, Sodium Methyl Paraben, Sodium Benzoate, cherry, strawberry, orange, tris buffer pH 5.5, tris buffer pH 6.5;, tris buffer pH 7.5, tris buffer pH 10, pH 5.5 with 0.01N HCI, among others.

[0160] Based on 4 weeks data collection it was observed that most of the excipients and buffers were incompatible with the warfarin active ingredient. This is in line with the observations made during the saturation solubility study. The oxidative impurity, impurity A, was found to increase with the majority of the excipients. Also, it was concluded that an increased temperature impacted the level of impurity A, as at 40°C / 75% RH storage condition impurity A was increased compared to other storage conditions (2°C-8°C; 25°C / 60% RH).

[0161] Some excipients showed excellent impurity control, such as propylene glycol, sodium sulphite, TPGS, Kollidon 12PF and HPMC.

[0162] The excipients listed in Table 2 were selected for further compatibility studies.

[0163] D. Bench Scale Study Based on the previous active ingredient - excipient compatibility studies a bench scale study was conducted. The compositions studied are provided in Table 3. The samples prepared in this study were put on stability to assess the formulation behavior in regular use and in different stress conditions. Table 1 : Results on physical stability, pH, solubility

[0164] Warfarin Sodium Clathrate

[0165] Solvents Warfarin Sodium (Amorphous)

[0166] (Crystalline)

[0167] Precipitation (21.46 mg / mL), No Precipitation (277 mg / mL) Purified water

[0168] pH 8.1 pH 9.84 Purified water + 5% Precipitation / turbid No Precipitation (224 mg / mL), w / v PVP K30 (8.35mg / mL); pH 6.58 pH 9.07 Purified water pH

[0169] No Precipitation (16.79 No Precipitation (350 mg / mL), adjusted using HCI &

[0170] mg / mL), pH 7.95 pH 9.43

[0171] NaOH- pH 5.5

[0172] Purified water pH

[0173] No Precipitation (11.15 No Precipitation (391 mg / mL), adjusted using HCI &

[0174] mg / mL), pH 7.86 pH 9.80

[0175] NaOH- pH 6.5

[0176] Purified water pH

[0177] Precipitation (9.28 mg / mL), No Precipitation (140 mg / mL), adjusted using HCI &

[0178] pH 7.81 pH 9.39

[0179] NaOH- pH 7.5

[0180] No solubility (0.005 mg / mL), No solubility (0.13 mg / mL), 0.1N HCI- pH 1.2

[0181] pH 1.01 pH 1.08

[0182] No solubility (0.008 mg / mL), No solubility (0.009 mg / mL), pH 4.5 acetate buffer

[0183] pH 4.85 pH 4.75

[0184] No solubility (0.21 mg / mL), No solubility (0.246 mg / mL), pH 5.5 Acetate buffer

[0185] pH 6.80 pH 6.73

[0186] O-Phosphoric acid 85%

[0187] No solubility (0.005 mg / mL), No solubility (0.02 mg / mL), USP Buffer [diluted to

[0188] pH -0.60 pH 0.64 45%]

[0189] 0.0 IM Citrate buffer- No solubility (0.005 mg / mL), No solubility (0.01 mg / mL), pH 3 pH 3.19 pH 3.95 0.0 IM Citrate buffer- No solubility (0.02 mg / mL), No solubility (0.02 mg / mL), pH 5 pH 5.55 pH 4.98 0.0 IM Citrate buffer- No solubility (0.24 mg / mL), No solubility (0.02 mg / mL), pH 6 pH 6.78 pH 7.09 0.01M Phosphate No solubility (0.23 mg / mL), No solubility (0.49 mg / mL), buffer- pH 6 pH 6.78 pH 7.0

[0190] 0.01M Phosphate Precipitated (1.22 mg / mL), Precipitated (4.92 mg / mL), buffer- pH 7 pH 7.44 pH 7.93 0.01M Phosphate Precipitation / turbid (18 No Precipitation (256 mg / mL), buffer- pH 8 mg / mL), pH 8.50 pH 9.38

[0191] TRIS-HCI buffer- pH 7.5 No Precipitation (35 mg / mL), No Precipitation (329 mg / mL)

[0192]

[0193] pH 9.01

[0194]

[0195] Table 2: Further excipient selection for compatibility studies

[0196] Category of excipients Selected excipients for 8 weeks analysis

[0197] Sweeteners sucralose, lycasin

[0198] Alkalizers sodium sulphite, glycine

[0199] Surfactants /

[0200] PEG6000, poloxamer P407

[0201] solubilizer

[0202] Vehicle / solvents propylene glycol, glycerin, benzyl alcohol, ethanol

[0203] Polymers Kollidon 12PF, HPMC 5cps, croscarmellose sodium Preservatives sodium methyl paraben, sodium propyl paraben, sodium benzoate purified water pH 5.5, Tris buffer pH 7.5, purified water, Tris buffer Buffer solutions

[0204] pH 5.5

[0205]

[0206] Samples for the bench scale studies were prepared as follows:

[0207] 1. Parabens were dissolved in propylene glycol or cosolvent and labeled as preservative solution.

[0208] 2. Sodium sulphite was dissolved in water, warfarin sodium was added to it. The combination was mixed for 10-15 mins to obtain a clear solution.

[0209] 3. To the solution obtained in step 2, HPMC was added. To this mixture obtained, the preservative solution prepared in step 1 was added.

[0210] 4. Other excipients were added to the product obtained in step 3. The pH of the buffer was adjusted based on requirements of the experiment.

[0211] The compositions of the samples prepared are summarized in Table 3.

[0212] The samples were stored at 25°C - 60% relative humidity (RH), 30°C - 65% relative humidity and 40°C - 25% relative humidity. The samples were analyzed for impurities and the pH was recorded. Analyses were conducted after sample preparation (initial) and after 1, 2, 3 and 6 months.

[0213] The samples were tested for its assay and impurities by HPLC using a modified USP method (USP29-NF24) with the following modifications:

[0214] Column: Ace Excel super C18, (250 mm x 4.6 mm), 5 pm

[0215] Column oven temperature : 45°C

[0216] Sample temperature: 25°C

[0217] Flow rate: 1.0 mL / minute Wavelength: 280 nm

[0218] Injection volume: 50 pL

[0219] Run time: 85 minutes

[0220] Retention time: about 27.4 minutes

[0221] Pump mode: Gradient program

[0222] Blank: Diluent: Buffer (Ph 7.4) and acetonitrile (85:15 v / v)

[0223] Needle Wash: 90% Acetonitrile in water

[0224] The results for the impurity level measurements in the bench scale studies are provided in Tables 4 and 5. The results for assay content of warfarin sodium and preservative (propyl paraben / methyl paraben) are provided in Table 6. Table 6 only contains the results for the samples that had a good outcome in the impurity analyses (samples SF22000341, SF22000342, SF22000346).

[0225] From the results obtained it was concluded that:

[0226] - The batches with acidic pH 5 to 6.5 (Batch no SF22000340, SF22000343, SF22000344, SF22000345) or containing IN HCI (SF22000346: pH 7.5) showed significant increase in impurity levels.

[0227] - The batches comprising a buffer agent (Batch no SF22000345, SF22000346, and SF22000347) showed a significant increase in impurity levels. known impurity A (oxidation product), B and C were found in low concentrations. Unknown impurities were found in higher levels at acidic pH. - The impurities were considerably higher at the accelerated condition of 40°C / 25%RH for all the batches.

[0228] - A suitable pH range for the formulation is pH 8 and above, more preferably above pH 9.

[0229] From the results obtained in Table 6, it was concluded that:

[0230] - The formulation with pH 9-10 had the lowest amount of impurities.

[0231] - The warfarin sodium content (assay) remained above a desired level in all samples. However, there was a drastic drop in the paraben levels at alkaline pH 9.7 and 9.8. Paraben degradation was not seen in samples at acidic pH and up to pH 8. It was also noticed that the presence of glycerin may have an impact on the assay of paraben preservatives at pH above 8.

[0232] - As it was desirable to have a pH above 9, and warfarin content remained stable above pH 9, it was decided to remove parabens. It was also found that sodium sulphite has a direct correlation with the pH of the formulation and the stability of the finished product. Table 3: Bench Scale Batches

[0233] SF2200 SF2200 SF2200 SF2200 SF2200 SF2200 SF2200 SF220 Ingredients Usage 0340 0341 0342 0343 0344 0345 0346 00347

[0234] % w / w

[0235] Warfarin sodium

[0236] amorphous API 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Propylene glycol 60 40 60 60 60 60 60 60 Glycerin Cosolvents 20

[0237] HPMC 5cps Viscosity

[0238] enhancer 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Benzoic acid 0.5

[0239] Sodium methyl

[0240] paraben Preservatives 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Sodium propyl

[0241] paraben 0.06 0.06 0.06 0.06 0.06 0.06 0.06 Sodium sulphite Antioxidant 0.05 N when 0.05 0.05 0.05 0.05 0.05 0.05 pH adjusted to pH

[0242] 5.5 using pH adjustment q.s.

[0243] IN NaOH

[0244] pH adjusted to pH

[0245] 5.5 using pH adjustment q.s.

[0246] IN HCI

[0247] pH adjusted to pH

[0248] 7.5 using pH adjustment q.s.

[0249] IN HCI

[0250] Tris buffer 5.5

[0251] (0.01M), IN HCI Buffer 0.121

[0252] Tris buffer 7.5

[0253] (0.01M), IN HCI Buffer 0.121 Citrate phosphate

[0254] buffer pH 5.5 Buffer q.s. Purified water Vehicle q.s.

[0255] Total batch size 100

[0256]

[0257] Theoretical water qu antity 37.35 37.59 37.59 37.59 1 37.59 37.07 37.07 37.2 Table 4: Results of bench scale studies (impurities, pH - at different time intervals) - part 1

[0258] #SF22000341 (Co-Solvent combination)

[0259] Impurity

[0260] name RRT Condition 25°C / 60% RH 30°C / 65% RH 40°C / 25% RH Initial 1 M 2 M 3 M 6 M 1 M 2 M 3 M 6 M 1 M 2 M 3 M 6 M Alice

[0261] ketone 1.017 NA 0.02 0.05 0.08 0.14 0.04 0.07 0.11 0.19 0.49 0.93 1.45 2.39 (Imp A)

[0262] 4

[0263] hydroxy

[0264] coumarin 0.772 ND ND ND ND ND ND ND ND ND ND ND 0.01 ND (Imp B)

[0265] Benzal- acetone 0.881 ND ND ND ND ND ND ND ND ND 0.02 ND 0.09 0.16 (Imp C)

[0266] Highest

[0267] unknown 0.03 0.03 0.03 0.04 0.03 0.03 0.04 0.03 0.03 0.04 0.04 0.08 0.19 Total NA 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.20 0.67 Unknown

[0268] Total 0 0.02 0.05 0.08 0.14 0.04 0.07 0.11 0.19 0.51 0.93 1.74 3.22 impurities

[0269] pH 9.72 9.71 9.64 9.38 9.21 9.69 9.55 9.34 9.16 9.14 8.84 8.57 8.18

[0270] #SF22000342 (Purified Water pH 9.4)

[0271] Impurity

[0272] name RRT Condition 25°C / 60% RH 30°C / 65% RH 40°C / 25% RH Initial IM 2M 3 M 6 M 1 M 2 M 3 M 6 M 1 M 2 M 3 M 6 M Alice

[0273] ketone 1.017 ND ND ND 0.03 0.06 0.02 0.03 0.04 0.09 0.24 0.5 0.72 1.31 (Imp A)

[0274] 4

[0275] hydroxy 0.772 ND ND ND ND ND ND ND ND ND 0.02 ND 0.01 ND coumarin

[0276] (Imp B)

[0277] Benzal- acetone 0.881 ND ND ND ND ND ND ND ND ND 0.01 0.05 0.09 0.172 (Imp C)

[0278] Highest

[0279] unknown 0.03 0.03 0.04 0.04 0.03 0.03 0.04 0.04 0.03 0.02 0.03 0.05 0.228 Total

[0280] Unknown 0.00 0.00 0.00 0.00 0.00 0.00 0.04 0.00 0.00 0.00 0.05 0.05 0.641 Total

[0281] impurities 0.00 0.00 0.00 0.03 0.06 0.02 0.03 0.04 0.09 0.27 0.55 0.87 2.125 pH 9.88 10.06 9.89 9.80 9.83 10.02 9.86 9.81 9.82 9.62 9.36 9.30 9.02

[0282] SF22000346 (Tris buffer pH 7.5 )

[0283] Impurity RRT Condition 25°C / 60% RH 30°C / 60% RH 40°C / 25% RH name

[0284] Initial 1 M 2 M 3 M 6 M 1 M 2 M 3 M 6 M 1 M 2 M 3 M 6 M Alice

[0285] ketone 1.017 NA 0.02 0.04 0.14 0.02 0.06 0.17 0.11 0.11 0.25 (Imp A)

[0286] 4

[0287] hydroxy

[0288] coumarin 0.772 ND ND ND 0.01 ND ND 0.02 ND ND ND (Imp B) NA NA NA Benzal- acetone 0.881 ND ND ND NA ND ND 0.01 0.08 0.22 0.4 (Imp C)

[0289] Highest 0.05 0.14 0.29 0.31 0.17 0.41 0.42 1.46 1.91 1.13 unknown

[0290] Total

[0291] Unknown NA 0.05 0.37 0.44 1.14 0.44 0.64 1.47 2.21 2.98 4.37 Total

[0292] impurities 0.05 0.39 0.48 1.29 0.47 0.7 1.67 2.4 3.31 5.02

[0293]

[0294] _ Pt! _ 7.46 7.15 6.75 6.54 6.92 6.70 6.44 6.36 6.25 6.10 Table 5: Results of bench scale studies (impurities, pH - at different time intervals) - part 2 / samples with significant increase in impurities

[0295] SF22000343 SF22000344

[0296] SF22000340 Purified Purified SF22000345 SF22000347, Batch no. benzoic acid, pH 5.5 Water, pH water, pH Tris buffer, Citrophosphate,

[0297] (IN NaOH)* 5.5 7.5 pH 5.5

[0298] (IN HCI pH 5.0 (IN HCI)* (IN HCI)* )*

[0299] Time points, Ti Time points, condition me points, Time points, Time points, condition condition condition condition Impurity

[0300] name

[0301] Initial IM, IM, IM, Initial IM, Initial IM, Initial IM,

[0302] 25 / 60 30 / 65 40 / 25 40 / 25 40 / 25 Initial IM,

[0303] 40 / 25 40 / 25 Alice ketone 0.11 0.05 0.05 0.07 0.13 0.03 ND 0.06 0.10 0.02 0.15 0.11 (Imp A)

[0304] 4 hydroxy

[0305] coumarin ND 0.09 0.03 ND ND 0.15 ND 0.07 ND 0.03 ND 0.47 (Imp B)

[0306] Benzal- acetone ND 0.015 0.02 0.38 ND 0.01 ND 0.17 ND 0.01 ND 0.23 (Imp C)

[0307] Highest 0.84 2.90 3.47 4.51 0.36 6.77 0.05 5.00 0.68 6.59 1.01 5.19 unknown

[0308] Total 1.78 3.99 4.76 6.51 1.04 9.27 0.05 7.41 1.50 9.05 2.10 9.05

[0309]

[0310] ND: Not detected, NA : Not Available / Not Applicable

[0311] *pH adjusted using IN NaOH / IN HCI solution.

[0312] Stability discontinued for the batches which showed significant rise in impurity after one month. Table 6: pH, preservative content, warfarin sodium assay and total impurities for selected batch scale batches.

[0313] Assay Related Batch Substances Number Condition PH Propyl Methyl Warfarin Total Paraben Paraben Sodium Impurities / w Initial 9.72 90.7 86.8 100.4 0.03 IM 25°C / 60%RH 9.71 86.2 65.1 98.3 0.02 IM 30°C / 60%RH 9.69 85.0 60.4 99.9 0.04 1M_4O°C / 25%RH 9.14 60.4 12.0 99.0 0.5 2M 25°C / 60%RH 9.64 82.9 53.4 99.2 0.05 SF22000341

[0314] 2M 30°C / 60%RH 9.55 81.6 47.0 100.4 0.07 2M_40°C / 25%RH 8.84 47.7 3.8 97.8 0.93 3M 25°C / 60%RH 9.38 79.3 42.6 98.6 0.08 3M 30°C / 60%RH 9.34 75.7 34.7 97.8 0.11 3M_40°C / 25%RH 8.57 38.9 1.5 95.1 1.74 Initial 9.88 99.2 86.8 98.5 0.03 IM 25°C / 60%RH 10.06 97.5 83.1 100.6 0.03 IM 30°C / 60%RH 10.02 97.1 80.7 100.8 0.03 1M_4O°C / 25%RH 9.62 82.6 37.1 99.9 0.28 2M 25°C / 60%RH 9.89 99.2 104.6 101.8 0.08 SF22000342

[0315] 2M 30°C / 60%RH 9.86 97.5 83.1 102.1 0.11 2M_40°C / 25%RH 9.35 97.1 80.7 102.1 0.6 3M 25°C / 60%RH 9.8 82.6 37.1 100.6 0.03 3M 30°C / 60%RH 9.81 93.9 75.8 100.6 0.04 3M_40°C / 25%RH 9.3 92.4 70.6 100.3 0.87 Initial 7.46 101.1 101.2 97.8 0.05 IM 25°C / 60%RH 7.15 101.7 99.9 99.6 0.4 IM 30°C / 60%RH 6.92 101.7 99.8 100.2 0.47 1M_4O°C / 25%RH 6.36 101.1 99.5 97.0 2.4 2M 25°C / 60%RH 6.75 102.0 100.9 99.7 0.48 SF22000346

[0316] 2M 30°C / 60%RH 6.7 101.6 100.4 99.0 0.7 2M_40°C / 25%RH 6.25 102.6 100.1 95.5 3.92 3M 25°C / 60%RH 6.54 101.2 100.6 98.1 1.29 3M 30°C / 60%RH 6.44 101.0 100.3 97.6 1.67

[0317]

[0318] 3M_40°C / 25%RH 6.1 103.0 99.9 93.6 5.02 E. Concentrations of Sodium sulphite

[0319] In an additional experiment, several concentrations of sodium sulphite were tested.

[0320] The formulations were prepared as follows:

[0321] 1. Dissolved sodium sulphite in water, added warfarin sodium. Mixed for 10-15 mins and obtained a clear solution.

[0322] 2. To the solution from step 1, added HPMC. To the solution obtained added 10% w / w ethanol.

[0323] 3. Added remainder of excipients ,such as propylene glycol, and adjusted the volume of the batch with water.

[0324] 4. Filtered the solution using a 5 micrometer filter.

[0325] 5. Filled HDPE bottles with above solution.

[0326] The formulations prepared are summarized in Table 7. The formulations were put on stability for a period of 4 or 8 weeks under the following conditions: 25±2°C and 60±5% Relative Humidity or 40±2°C and 25±5% Relative Humidity. The results of different concentrations of sodium sulphite on formulation stability are provided in Table 8. The results obtained were satisfactory for all sodium sulphite concentrations selected.

[0327] Table 7: Formulations with different sodium sulphite concentrations.

[0328] SF23000014 SF23000015 SF23000016 SF24000017 Ingredients

[0329] %w / w % w / w % w / w % w / w Warfarin sodium

[0330] 0.1 0.1 0.1 0.1 amorphous

[0331] Propylene glycol 76.0 76.0 76 76 HPMC 3.0 3.0 3 3 Sodium sulphite 0.6 0.2 0.4 0.8 Ethanol 10 10 10 10

[0332]

[0333] Q.S to 100 Q.S to 100 Q.S to 100 Q.S to 100 Purified water

[0334] % % % %

[0335]

[0336] Table 8: Sodium sulphite effect on stability

[0337] Batch SF23000014 SF23000015 Number

[0338] Time Point Initial 4 Weeks 8 Weeks Initial 4 Weeks 8 Weeks Condition RT 25°C / 40°C / 25°C / 40°C / RT 25°C / 40°C / 25°C / 40°C /

[0339] 60 % 25 % 60 % 25 % 60 % 25 % 60 % 25 % RH RH RH RH RH RH RH RH

[0340] Imp. A NA 0.01 0.02 0.01 0.02 NA 0.02 0.03 0.01 0.04 Imp. B NA NA NA 0.00 0.01 NA NA NA 0.00 0.01 Imp. C NA NA NA 0.00 0.00 NA NA NA 0.00 0.00 total unknow NA NA NA 0.05 0.05 NA NA NA 0.05 0.00 n

[0341] Total NA 0.01 0.03 0.06 0.08 NA 0.02 0.03 0.06 0.05 Impurity (%)

[0342] PH 10.2 10.31 10.49 10.4 10.43 10.1 10.19 10.04 10.11 10.12

[0343]

[0344] 5

[0345] Table 8 (continued)

[0346] Batch SF23000016 SF2400017

[0347] Number

[0348] Time Point Initial 4 Weeks 8 Weeks Initial 4 Weeks 8 Weeks Condition RT 25°C / 40°C / 25°C / 40°C / RT 25°C / 40°C / 25°C / 40°C /

[0349] 60 % 25 % 60 % 25 % 60 % 25 % 60 % 25 % RH RH RH RH RH RH RH RH

[0350] Imp. A NA 0.01 0.02 0.01 0.03 NA 0.01 0.02 0.01 0.02 Imp. B NA NA NA 0.00 0.01 NA NA NA 0.00 0.01 Imp. C NA NA NA 0.00 0.00 NA NA NA 0.00 0.00 total unknown NA NA NA 0.05 0.05 NA NA NA 0.05 0.05 Total Impurity NA 0.01 0.03 0.06 0.09 NA 0.01 0.02 0.05 0.10 (%)

[0351] PH 10.23 10.26 10.43 10.25 10.63 10.23 10.26 10.43 10.25 10.53

[0352]

[0353] F. Control of microbial growth

[0354] Formulations with different ethanol content ranging from 0% to 10% were tested and compared for control of microbial growth. Each formulation was compared with a formulation without warfarin sodium (placebo). The antimicrobial effectiveness test was conducted in accordance with USP51. The formulations tested are summarized in Table 9.

[0355] Table 9 Selection of Ethanol concentration for Warfarin Oral solution

[0356] SF23000016 SF23000017 SF23000018 SF23000019 Ingredients

[0357] % w / w % w / w % w / w % w / w Warfarin sodium

[0358] 0.1 0.1 0.1 0.1 amorphous

[0359] Propylene glycol 76.0 76.0 76.0 70.0 HPMC 5cps 3.0 3.0 3.0 3.0 Sodium sulphite 0.4 0.4 0.4 0.4 Ethanol 0.0 0.5 2.0 10.0 Purified water 35.0 35.0 35.0 35.0

[0360]

[0361] The formulations were prepared as follows:

[0362] 1. Dissolved sodium sulphite in water, added warfarin sodium. Mixed for 10-15 minutes to obtain a clear solution.

[0363] 2. To the solution from step 1, added HPMC. To this solution add ethanol in varying concentrations as indicated in Table 12.

[0364] 3. Added remainder of excipients and adjusted the volume of the batch with water to the desired volume.

[0365] 4. Filtered the solution using a 5 micrometer filter.

[0366] 5. Filled the HDPE bottles with a formulation and heat sealed the bottle.

[0367] It was concluded that :

[0368] Both active and placebo samples had similar level of antimicrobial control. This suggests that the formulation vehicle (about 60% non-aqueous solvent such as propylene glycol) and the basic pH of the formulation (especially pH 9-10) is sufficient to prevent microbial growth. - All concentrations of ethanol tested achieved desired antimicrobial control. - Both Active and placebo batch have shown similar level of antimicrobial effectiveness during testing., suggesting that formulation vehicle is sufficient to prevent microbial growth in finished product.

[0369] - All alcohol concentrations have been found to be effective to achieve desired antimicrobial effectiveness. Apart from API and Ethanol other component in composition can be further studied for observed antimicrobial effectiveness.

[0370] G. Most preferred compositions and storage stability

[0371] As a final step, a sweetener and / or flavor and / or sweetener may be added to improve the palatability of a selected formulation. A preferred sweetener is sucralose. A preferred flavor is orange flavor, peppermint or cherry

[0372] Compositions were prepared as follows:

[0373] 1. Dissolved sodium sulphite in water, added warfarin active ingredient in it.

[0374] Mixed it for 10-15 mins to obtain a clear solution.

[0375] 2. To the solution from step 1, add HPMC. To this solution added ethanol.

[0376] 3. Added the remainder of the excipients including a flavor and / or sweetener and adjusted the volume of the batch with water to a desired volume.

[0377] 4. Filtered the solution using a 5 micrometer filter.

[0378] 5. Filled HDPE and glass bottles with the above solution.

[0379] The compositions thus prepared are provided in Tables 10-12.

[0380] The formulations SF23000466, SF23000467 and SF23000468 were put on stability for a period of 4 or 8 weeks under the following conditions: cold (2-8°C), 25±2°C and 60±5% Relative Humidity, 40±2 °C and 25±5% Relative Humidity (tables 13 to 14).

[0381] Surprisingly, the compositions according to the invention are storage stable at 40°C and 75% relative humidity, as well as remain free from crystal growth or precipitation at refrigerator conditions (2-8 °C). They are also protected against microbial growth. Palatability of the oral solution makes the formulations particularly suitable for use in a pediatric and geriatric patient population. Table 10: Preferred Compositions according to the invention

[0382] Ingredients SF23000466 SF23000467 SF23000468

[0383] % VJ / VJ % VJ / VJ % VJ / VJ Warfarin sodium amorphous 0.10 0.10 0.10 Propylene glycol 60.50 60.50 60.50 HPMC 3.00 3.00 3.00 Sodium sulphite 0.40 0.40 0.40 Ethanol 0.50 0.50 0.50 Sucralose 0.00 1.00 1.00 Peppermint 0.00 0.00 0.10

[0384]

[0385] Purified water 35.50 34.50 34.40

[0386] Table 11: Preferred compositions according to the invention

[0387] Ingredients

[0388] % VJ / VJ % VJ / VJ % VJ / VJ Warfarin sodium amorphous 0.10 0.10 0.10 Propylene glycol 60.50 60.50 60.50 HPMC 3.00 3.00 3.00 Sodium sulphite 0.30 0.50 0.60 Ethanol 0.50 0.50 0.50 Sucralose 0.00 1.00 1.00 Peppermint 0.00 0.00 0.10

[0389]

[0390] Purified water 35.50 34.50 34.40

[0391] Table 12: Most preferred composition according to the invention

[0392] Ingredients Warfarin oral solution 1 mg / ml

[0393] spec Use % w / w mg / ml Warfarin sodium IH Active 0.10 1.0 amorphous

[0394] Propylene glycol USP-NF Diluent 60.50 605.0

[0395] HPMC 5cps USP-NF viscosity modifying 3.00 30 Sodium sulphite USP-NF Antioxidant & pH 0.50 5.0

[0396] modulator

[0397] Ethanol USP-NF Co-solvent & 0.50 5.0

[0398] preservative

[0399] Sucralose USP-NF Sweetener 1.00 10.0 Purified water USP Diluent Q.S to 100 % Q.S to 100

[0400]

[0401] % As the antioxidant may be partly consumed during storage, a concentration of 0,50 mg / ml is most preferred. Table 13: Data evaluation correlation for pH, sodium sulphite, dissolved oxygen and impact on impurities

[0402] Batch No: SF23000466; Cold (2-8°C)- HDPE Container

[0403] Alice Highest Total Dissolved Sodium Sulphite

[0404] Months pH Ketone Unknown Impurity Oxygen (mg / ml)

[0405] (Imp-A), % (%) (%) % 0 9.98 3.74 ND 0.08 0.08 5.55 1 10.05 3.61 ND 0.06 0.06 5.46 2 10.01 3.44 ND 0.05 0.05 6.08 3 9.82 3.18 0.03 0.03 0.04 5.3 Batch No: SF23000466; Room Temperature (25°C / 60 % RH)- HDPE Container Alice Dissolved Sodium Sulphite Highest Total

[0406] Months pH Ketone Oxygen (mg / ml) Unknown Impurity

[0407] (Imp-A), % % 0 9.98 3.74 ND 0.08 0.08 5.55 1 10.04 3.53 ND 0.05 0.05 5.88 2 10.04 3.03 0.01 0.06 0.08 6.15 3 10.04 2.91 0.01 0.04 0.02 5.36 Batch No: SF23000466; ACC Condition (40°C / 25 % RH)- HDPE Container Alice Dissolved Sodium Sulphite Highest Total

[0408] Months pH Ketone Oxygen (mg / ml) Unknown Impurity

[0409] (Imp-A), % % 0 9.98 3.74 ND 0.08 0.08 5.55 1 10.15 3.10 ND 0.05 0.05 6.21 2 10.1 2.44 0.04 0.04 0.36 6.75

[0410]

[0411] 3 9.96 2.21 0.05 0.06 0.21 5.1 Table 14: Data evaluation correlation for pH, sodium sulphite, dissolved oxygen and impact on impurities

[0412] Batch No: SF23000467; Cold (2-8°C)- HDPE Container

[0413] Sodium Alice Highest

[0414] Total Dissolved Months pH Sulphite Ketone Unknown

[0415] Impurity (%) Oxygen % (mg / ml) (Imp-A), % (%)

[0416] 0 10.01 3.73 ND 0.08 0.08 6.30 1 9.79 3.78 ND 0.06 0.06 6.34 2 9.88 3.42 0.01 0.02 0.02 6.14 3 9.55 3.12 0.03 0.03 0.04 6.00 Batch No: SF23000467; Room Temperature (25°C / 60 % RH)- HDPE Container Sodium Alice

[0417] Highest Total Dissolved Months pH Sulphite Ketone

[0418] Unknown Impurity Oxygen % (mg / ml) (Imp-A), %

[0419] 0 10.01 3.73 ND 0.08 0.08 6.30 1 9.53 3.25 ND 0.04 0.00 6.42 2 9.63 2.63 ND 0.05 0.06 5.57 3 9.31 2.78 0.01 0.05 0.07 5.69 Batch No: SF23000467; ACC Condition (40°C / 25 % RH)- HDPE Container Sodium Alice

[0420] Highest Total Dissolved Months pH Sulphite Ketone

[0421] Unknown Impurity Oxygen % (mg / ml) (Imp-A), %

[0422] 0 10.01 3.73 ND 0.08 0.08 6.30 1 9.03 2.58 ND 0.08 0.13 5.57 2 8.86 2.20 0.03 0.06 0.18 5.49

[0423]

[0424] 3 8.13 0.71 0.10 0.05 0.20 5.77 Table 15: Data evaluation correlation for pH, sodium sulphite, dissolved oxygen and impact on impurities

[0425] Batch No: SF23000468; ACC Condition (40°C / 25 % RH)- HDPE Container Months pH Sodium Alice Highest Total Dissolved Sulphite Ketone Unknown Impurity Oxygen % (mg / ml) (Imp-A), % %

[0426] %

[0427] 0 10.03 3.772 ND 0.06 0.07 5.79 1 9.35 2.552 0.02 0.07 0.17 4.43 2 9.19 2.456 0.03 0.07 0.26 6.61 3 8.35 1.012 0.07 0.06 0.18 3.78 Batch No: SF23000468; Room Temperature (25°C / 60 % RH)- HDPE Container Months pH Sodium Alice Highest Total Dissolved Sulphite Ketone Unknown Impurity Oxygen % (mg / ml) (Imp-A), % %

[0428] %

[0429] 0 10.03 3.77 ND 0.06 0.07 5.79 1 9.74 3.19 ND 0.04 0.00 5.53 2 9.51 2.88 ND 0.06 0.06 4.06 3 9.37 2.38 0.01 0.04 0.02 4.52 Batch No: SF23000468; Cold Condition (2-8°C)- HDPE Container Months pH Sodium Alice Highest Total Dissolved Sulphite Ketone Unknown Impurity Oxygen % (mg / ml) (Imp-A), % %

[0430] %

[0431] 0 10.03 3.77 ND 0.06 0.07 5.79 1 9.72 3.54 ND 0.04 0.00 4.57 2 9.47 3.54 ND 0.05 0.05 4.48 3 9.61 3.28 0.00 0.02 0.01 6.02

[0432]

[0433] H. Compositions with arginine

[0434] Compositions were prepared as follows:

[0435] 1. Dissolved arginine in water, added warfarin active ingredient in it. Mixed it for 10-15 mins to obtain a clear solution.

[0436] 2. To the solution from step 1, add HPMC. To this solution added ethanol.

[0437] 3. Added the remainder of the excipients including a flavor and / or sweetener and adjusted the volume of the batch with water to a desired volume.

[0438] 4. Filtered the solution using a 5 micrometer filter.

[0439] 5. Filled HDPE and glass bottles with the above solution.

[0440] The compositions thus prepared are provided in Tables 16-18.

[0441] The formulations 25-009 / 010 and 25-011 were put on stability for a period of 1 month at 25°C / 60% Relative Humidity conditions, (tables 20 and 21).

[0442] The samples were tested for its assay and impurities by HPLC using a modified USP method (USP29-NF24) with the following modifications:

[0443] Column: Ace Excel super C18, (250 mm x 4.6 mm), 5 pm

[0444] Column oven temperature : 45°C

[0445] Sample temperature: 25°C

[0446] Flow rate: 1.0 mL / minute

[0447] Wavelength: 280 nm

[0448] Injection volume: 50 pL

[0449] Run time: 85 minutes

[0450] Retention time: about 27.4 minutes

[0451] Pump mode: Gradient program

[0452] Blank: Diluent: Buffer (Ph 7.4) and acetonitrile (85:15 v / v)

[0453] Needle Wash: 90% Acetonitrile in water Table 16: Preferred Compositions according to the invention

[0454] Ingredients 25-001 25-005 25-006 25-007 25-009 / 25-011

[0455] 0010

[0456] % w / w % w / w % w / w % w / w % w / w % w / w Warfarin 0.10 0.10 0.10 0.10 0.10 0.10 sodium

[0457] amorphous

[0458] Propylene 60.50 60.50 40.04 50.05 45.05 45.05 glycol

[0459] HPMC 3.00 3.00 3.00 3.00 3.00 3.00 Arginine 1.00 3.00 1.00 1.00 1.00 1.00 Ethanol 0.50 0.50 0.50 0.50 0.50 0.50 Sucralose 1.00 1.00 1.00 1.00 1.00 1.00 Blood orange - - - - - 0.2 flavor

[0460] Purified water Q.S. to Q.S. to Q.S. to Q.S. to Q.S. to Q.S. to

[0461]

[0462] 100% 100% 100% 100% 100% 100% Table 17: Preferred Compositions according to the invention

[0463] Ingredients 25-006 25-007 25-009 / 010

[0464] % w / w % w / w % w / w

[0465] Warfarin sodium amorphous 0.10 0.10 0.10

[0466] Propylene glycol 40.04 50.05 45.05

[0467] HPMC 3.00 3.00 3.00

[0468] Arginine 1.00 1.00 1.00

[0469] Ethanol 0.50 0.50 0.50

[0470] Sucralose 1.00 1.00 1.00

[0471] Purified water Q.S. to Q.S. to Q.S. to 100%

[0472]

[0473] 100% 100%

[0474] Table 18: Most preferred composition according to the invention

[0475] Ingredients Warfarin oral solution 1 mg / ml

[0476] spec Use % w / w mg / ml Warfarin sodium IH Active 0.10 1 amorphous

[0477] Propylene glycol USP-NF Diluent 45.05 450 HPMC 5cps USP-NF viscosity 3.00 30 modifying

[0478] Arginine USP-NF Antioxidant & pH 1.0 10 modulator

[0479] Ethanol USP-NF Co-solvent & 0.50 5 preservative

[0480] Sucralose USP-NF Sweetener 1.00 10 Purified water USP Diluent Q.S to 100 Q.S to 1

[0481]

[0482] % mg / mL Table 19: Data evaluation correlation for pH, arginine, and visual inspection

[0483] Batch number 25-001 25-005 25-006 25-007 25-009 / 010 pH Initial 10.26 10.35 10.22 10.33 10.35 pH after 3

[0484] 9.69 9.68 9.37 N / A 10.16 months (30 / 75)

[0485] Visual

[0486] observation Clear Clear Clear Clear Clear (initial)

[0487] Visual Clear Clear Clear

[0488] observation at 4 Clear (dark (pale (pale Clear weeks - 2-8C yellow) yellow) yellow)

[0489]

[0490] Table 20: Data evaluation correlation for pH, arginine, and impact on impurities of composition 25-009 / 010 in HDPE - 200 ml / bottle or Glass amber type III - 50 ml / bottle at 25°C / 60%RH.

[0491] Batch TO (Initial) HDPE - 200 Glass amber type III 25-009 / 010 ml / bottle - 50 ml / bottle

[0492] pH 10.14 10.02 9.88

[0493] Related % % %

[0494] substances

[0495] Impurity A ND ND ND

[0496] Impurity B ND ND ND

[0497] Impurity C 0.058 0.062 0.064

[0498] Single Max. ND 0.051 0.061

[0499]

[0500] Total impurities 0.058 0.113 0.326

[0501] Table 21: Data evaluation correlation for pH, arginine, and impact on impurities of composition 25-011 in HDPE - 200 ml / bottle or Glass amber type III - 50 ml / bottle at 25°C / 60%RH.

[0502] Batch TO (Initial) HDPE - 200 Glass amber type 25-011 ml / bottle III - 50 ml / bottle pH 10.02 9.95 9.92

[0503] Related % % %

[0504] substances

[0505] Impurity A ND ND ND

[0506] Impurity B 0.058 ND ND

[0507] Impurity C 0.064 0.062 0.062

[0508] Single Max. 0.082 0.190 0.051

[0509]

[0510] Total impurities 0.204 0.252 0.158 Surprisingly it was found all the compositions comprising arginine presented good stability and had a pH higher than 9. It was also found that arginine has a direct correlation with the pH of the formulation and the stability of the finished product.

Claims

Claims1. A liquid, multi-dose, ready-to-use, pharmaceutical composition comprising: a) warfarin or a salt thereof,b) an excipient that is both an antioxidant and pH regulator, andc) a fluid;wherein the composition has a pH of 8.0 - 11.0.

2. The pharmaceutical composition according to claim 1, wherein b) the excipient that is both an antioxidant and pH regulator, is sodium sulphite.

3. The pharmaceutical composition according to claim 2, comprising 2 mg / ml to 10 mg / ml sodium sulphite.

4. The pharmaceutical composition according to claim 1, wherein b) the excipient that is both an antioxidant and pH regulator, is arginine.

5. The pharmaceutical composition according to claim 4, comprising 2 mg / ml to 50 mg / ml arginine.

6. The pharmaceutical composition according to any of the preceding claims, wherein the pharmaceutical composition has a pH of 9.1 -10.7.

7. The pharmaceutical composition according to any of the preceding claims, wherein the composition when stored for three months in a sealed, sterile container at 25°C / 60% RH and 40°C / 25% RH contains no more than 1.0% total impurity as measured by HPLC.

8. The pharmaceutical composition according to any of the preceding claims, wherein the pharmaceutical composition is in the form of an oral solution, preferably a palatable oral solution.

9. The pharmaceutical composition according to any of the preceding claims, wherein c) the fluid is selected from an aqueous solution, propylene glycol (PG) or combinations thereof.

10. The pharmaceutical composition according to any of the preceding claims, with the proviso that glycerin and parabens are excluded.

11. The pharmaceutical composition according to any of the preceding claims, with the proviso that a buffer agent is excluded, preferably sodium phosphate buffer is excluded.

12. The pharmaceutical composition according to any of the preceding claims, comprising warfarin sodium, warfarin potassium, warfarin clathrate or a combination thereof.

13. The pharmaceutical composition according to claim 12, wherein warfarin sodium is present in an amount of 0.1 to 20 mg / ml; preferably 0.2 to 10 mg / ml; more preferably 0.5 to 5 mg / ml; most preferably 1 mg / ml of the pharmaceutical composition.

14. The pharmaceutical composition according to any of the preceding claims, further comprising e) a preservative in a suitable concentration for protection of the composition against bacterial growth; preferably the preservative is ethanol.

15. The pharmaceutical composition according to any of the preceding claims with a cold storage stability as measured at 2°C-8°C of at least 3 months.

16. The pharmaceutical composition according to any of the preceding claims, comprising a sweetener, preferably sucralose.

17. The pharmaceutical composition according to claim 16, wherein the sweetener is present in an amount of 0.1 to 20 mg / ml.

18. The pharmaceutical composition according to any of the preceding claims, for use as a medicine.

19. The pharmaceutical composition according to claim 18, for use in the treatment of venous thrombosis, pulmonary embolism, thromboembolic complications associated with atrial fibrillation and / or cardiac valve replacement, in the reduction in the risk of death, recurrent myocardial infarction, thromboembolic events, such as stroke or systemic embolization, after myocardial infarction.

20. The pharmaceutical composition according to claim 18 or 19, wherein the composition is used for the treatment of a pediatric or geriatric patient or a patient having difficulties swallowing.

21. A kit comprising at least one pharmaceutically acceptable container containing one or more doses of the pharmaceutical composition according to any of claims 1 to 20 in combination with instructions for storage and use of the kit.

22. A method of producing a pharmaceutical composition, preferably according to an embodiment of the invention, comprising the steps of: dissolving sodium sulphite or arginine in water in an amount sufficient to obtain a solution of pH 8-10, adding warfarin or a pharmaceutically acceptable salt to said aqueous sodium sulphite or arginine solution and adding propylene glycol, thereby obtaining the pharmaceutical composition.

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