Patent Application
20130225830
The present invention relates to new crystalline forms of febuxostat, pharmaceutical compositions comprising same, and use thereof in treating hyperuricaemia.
Febuxostat is a potent, selective, non-purine inhibitor of xanthine oxidase. Febuxostat has been approved for the treatment of chronic hyperuricaemia in conditions in which urate deposition has occurred, such as gouty arthritis.
Febuxostat is chemically named 2-(3-cyano-4-isobutoxyphenyl)-4-methyl-5-thiazolecarboxylic acid, and is represented by the following chemical structure:
Febuxostat and processes for its preparation are disclosed in EP 0513379, JP 1993500083, U.S. Pat. No. 5,614,520 and WO 92/09279, JP 10-045733, JP 10-139770, JP 1994345724 (JP 6-345724), in publications in Heterocycles, 1998, 47: 857-864 and Org. Lett., 2009, 11(8): 1733-1736, and in PCT international patent application PCT/IL2010/000807 to some of the inventors of the present invention.
A new crystalline or amorphous form of a compound may possess physical properties that differ from, and are advantageous over, those of other crystalline or amorphous forms. These include, packing properties such as molar volume, density and hygroscopicity; thermodynamic properties such as melting temperature, vapor pressure and solubility; kinetic properties such as dissolution rate and stability under various storage conditions; surface properties such as surface area, wettability, interfacial tension and shape; mechanical properties such as hardness, tensile strength, compactibility, handling, flow and blend; and filtration properties. Variations in any one of these properties affect the chemical and pharmaceutical processing of a compound as well as its bioavailability and may render the new form advantageous for medical use.
EP 0513379 discloses a polymorph of febuxostat having a melting point of about 238-239° C. (decomposed).
U.S. Pat. No. 6,225,474 and U.S. Pat. No. 7,361,676 disclose six polymorphs of febuxostat, five crystalline polymorphs designated Forms A, B, C, D, and G and one amorphous form. Form A is characterized by the following X-ray diffraction peaks at about 6.62, 7.18, 12.80, 13.26, 16.48, 19.58, 21.92, 22.68, 25.84, 26.70, 29.16 and 36.70 2θ°; Another process for the preparation of Form A is disclosed in WO 2011/007895; Form B is characterized by the following X-ray diffraction peaks at about 6.76, 8.08, 9.74, 11.50, 12.22, 13.56, 15.76, 16.20, 17.32, 19.38, 21.14, 21.56, 23.16, 24.78, 25.14, 25.72, 26.12, 26.68, 27.68 and 29.36 2θ°; Form C is characterized by the following X-ray diffraction peaks at about 6.62, 10.82, 13.36, 15.52, 16.74, 17.40, 18.00, 18.70, 20.16, 20.62, 21.90, 23.50, 24.78, 25.18, 34.08, 36.72 and 38.04 2θ°; Form D (methanolate) is characterized by the following X-ray diffraction peaks at about 8.32, 9.68, 12.92, 16.06, 17.34, 19.38, 21.56, 24.06, 26.00, 30.06, 33.60 and 40.34 2θ°; and Form G (hydrate) is characterized by the following X-ray diffraction peaks at about 6.86, 8.36, 9.60, 11.76, 13.74, 14.60, 15.94, 16.74, 17.56, 20.00, 21.26, 23.72, 24.78, 25.14, 25.74, 26.06, 26.64, 27.92, 28.60, 29.66 and 29.98 2θ°.
CN 101386605 discloses a crystalline form of febuxostat designated as Form K, the form is characterized by the following X-ray diffraction peaks between 5.44 and 5.84, between 7.60 and 8.00, between 11.18 and 11.58, between 11.50 and 11.90, between 12.34 and 12.74, between 12.54 and 12.94, between 16.98 and 17.38, and between 25.92 and 26.32 2θ°.
CN 101412700 discloses a crystalline form of febuxostat which is characterized by the following X-ray diffraction peaks at 5.54±0.2, 5.66±0.2, 7.82±0.2, 11.48±0.2, 12.62±0.2, 16.74±0.2, 17.32±0.2, 18.04±0.2, 18.34±0.2, 20.40±0.2, 23.74±0.2, 25.76±0.2, and 26.04±0.2 2θ°.
WO 2008/067773 and CN 101474175 disclose three crystalline forms of febuxostat designated Forms H, I and J. Form H is characterized by the following X-ray diffraction peaks at about 6.71, 7.19, 10.03, 11.10, 12.96, 13.48, 15.78, 17.60 and 22.15 2θ°. Form I is characterized by the following X-ray diffraction peaks at about 3.28, 6.58, 12.70, 13.34, 19.97, 24.26, and 25.43 2θ°. Form J is characterized by the following X-ray diffraction peaks at about 3.07, 12.25, 13.16, 25.21, and 26.86 2θ°.
Other crystalline forms of febuxostat are described in CN 101928260, WO 2010/144685, CN 101891703, CN 101891702, CN 101759656, CN 101857578, CN 101824005, CN 101824007, CN 101824006, CN 101817801, CN 101805310, CN 101768136, CN 101768150, CN 101759656, CN 101684108, CN 101684107, CN 101671314, CN 101671315, CN 101648926, and CN 101139325.
There remains an unmet need for additional solid state forms of febuxostat having good physiochemical properties, desirable bioavailability, and advantageous pharmaceutical parameters.
The present invention provides new crystalline forms of febuxostat, including anhydrous and solvated forms of febuxostat, pharmaceutical compositions comprising said forms, methods for their preparation and use thereof in treating hyperuricaemia.
The present invention is based in part on the unexpected finding that the new forms disclosed herein possess advantageous physicochemical properties which render their processing as medicaments beneficial. The forms of the present invention have good bioavailability as well as desirable hygroscopicity and stability characteristics enabling their incorporation into a variety of different formulations particularly suitable for pharmaceutical utility. Furthermore, anhydrous febuxostat (Form IX) of the present invention shows improved solubility at colon-simulated media (pHs=6.8-7.4) and intestinal fluids, thus indicating possible improved bioavailability.
According to one aspect, the present invention provides a crystalline form of febuxostat hydrate (Form II) having an X-ray powder diffraction pattern with diffraction peaks at 2-theta values at about 4.8±0.1, 6.9±0.1, 8.3±0.1, 9.6±0.1, 11.7±0.1, 13.7±0.1, 15.6±0.1, 16.7±0.1, 17.6±0.1, 19.9±0.1, 23.7±0.1, 25.2±0.1, 28.7±0.1, 30.0±0.1 and 34.3±0.1.
In one embodiment, the present invention provides a crystalline febuxostat hydrate (Form II) having an X-ray powder diffraction pattern substantially as shown in
In certain embodiments, the present invention provides a process for preparing crystalline febuxostat hydrate (Form II), the process comprising the steps of:
In some embodiments, the solvents in the mixture of solvents are at a volume ratio of 1:1.
According to another aspect, the present invention provides a crystalline febuxostat N-methylpyrrolidone (i.e. NMP) solvate (Form IV) having an X-ray powder diffraction pattern with diffraction peaks at 2-theta values of about 4.0±0.1, 4.9±0.1, 6.4±0.1, 6.9±0.1, 7.5±0.1, 8.0±0.1, 8.3±0.1, 10.1±0.1, 10.7±0.1, 11.7±0.1, 12.3±0.1, 14.0±0.1, 16.0±0.1, 16.7±0.1, 17.2±0.1, 17.6±0.1, 18.8±0.1, 20.1±0.1, 20.9±0.1, 21.6±0.1, 23.2±0.1, 23.6±0.1, 25.2±0.1, and 26.2±0.1.
In some embodiments, the present invention provides a crystalline febuxostat NMP solvate (Form IV) having an X-ray powder diffraction pattern substantially as shown in
In certain embodiments, the present invention provides a process for preparing crystalline febuxostat NMP solvate (Form IV), the process comprising the steps of:
In some embodiments, the solvents in the mixture of solvents are at a volume ratio of 1:1.
According to another aspect, the present invention provides a crystalline febuxostat NMP solvate (Form VI) having an X-ray powder diffraction pattern with diffraction peaks at 2-theta values of about 4.1±0.1, 7.0±0.1, 7.6±0.1, 8.3±0.1, 10.0±0.1, 11.4±0.1, 12.5±0.1, 13.7±0.1, 14.1±0.1, 15.4±0.1, 17.1±0.1, 17.6±0.1, 19.6±0.1, 21.5±0.1, 23.0±0.1, 24.9±0.1, 25.3±0.1, 25.6±0.1, 26.2±0.1, 27.1±0.1, and 29.9±0.1.
In some embodiments, the present invention provides a crystalline febuxostat NMP solvate (Form VI) having an X-ray powder diffraction pattern substantially as shown in
In further embodiments, the present invention provides a process for preparing crystalline febuxostat NMP solvate (Form VI), the process comprising the steps of:
According to yet another aspect, the present invention provides a crystalline febuxostat DMSO solvate (Form V) having an X-ray powder diffraction pattern with diffraction peaks at 2-theta values of about 7.1±0.1, 10.6±0.1, 11.7±0.1, 13.8±0.1, 14.3±0.1, 15.2±0.1, 16.2±0.1, 16.9±0.1, 17.2±0.1, 19.4±0.1, 21.0±0.1, 21.6±0.1, 21.8±0.1, 22.1±0.1, 22.5±0.1, 22.7±0.1, 23.5±0.1, 24.8±0.1, 26.4±0.1, and 28.7±0.1.
In some embodiments, the present invention provides a crystalline febuxostat DMSO solvate (Form V) having an X-ray powder diffraction pattern substantially as shown in any of
In further embodiments, the present invention provides a process for preparing crystalline febuxostat DMSO solvate (Form V), the process comprising the steps of:
In some embodiments, the solvents in the mixture of solvents are at a volume ratio of 1:1. In other embodiments, the process for preparing crystalline febuxostat DMSO solvate (Form V) further comprises the steps of:
According to another aspect, the present invention provides a crystalline febuxostat DMSO solvate (Form VII) having an X-ray powder diffraction pattern with diffraction peaks at 2-theta values of about 4.0±0.1, 7.2±0.1, 8.0±0.1, 11.4±0.1, 13.6±0.1, 13.9±0.1, 14.7±0.1, 17.1±0.1, 17.8±0.1, 20.5±0.1, 21.5±0.1, 22.7±0.1, 23.0±0.1, 25.2±0.1, 26.3±0.1, and 27.8±0.1.
In some embodiments, the present invention provides a crystalline febuxostat DMSO solvate (Form VII) having an X-ray powder diffraction pattern substantially as shown in
In further embodiments, the present invention provides a process for preparing crystalline febuxostat DMSO solvate (Form VII), the process comprising the steps of:
According to another aspect, the present invention provides a crystalline febuxostat anhydrous (Form VIII) having an X-ray powder diffraction pattern with diffraction peaks at 2-theta values of about 3.6±0.1, 7.1±0.1, 12.4±0.1, 13.3±0.1, 17.6±0.1, 23.1±0.1, 25.2±0.1, 27.0±0.1, and 27.6±0.1.
In some embodiments, the present invention provides a crystalline anhydrous febuxostat (Form VIII) having an X-ray powder diffraction pattern substantially as shown in
In further embodiments, the present invention provides a process for preparing crystalline anhydrous febuxostat (Form VIII), the process comprising the steps of:
In some embodiments, the cooling in step (b) is selected from fast cooling and slow cooling. Each possibility represents a separate embodiment of the invention.
According to another aspect, the present invention provides a crystalline anhydrous febuxostat (Form IX) having an X-ray powder diffraction pattern with diffraction peaks at 2-theta values of about 4.6±0.1, 6.1±0.1, 7.3±0.1, 9.2±0.1, 11.6±0.1, 13.3±0.1, 16.3±0.1, 17.3±0.1, 18.5±0.1, 23.0±0.1, 25.7±0.1, 26.5±0.1 and 28.3±0.1.
In some embodiments, the present invention provides a crystalline anhydrous febuxostat (Form IX) having an X-ray powder diffraction pattern substantially as shown in any of
In further embodiments, the present invention provides a process for preparing crystalline anhydrous febuxostat (Form IX), the process comprising the steps of:
In one embodiment, the solvent in step (a) is EtOAc. In some embodiments, the evaporation in step (b) is performed using rotary evaporator, preferably at a temperature of 50° C. or below. In other embodiments, the process for preparing crystalline anhydrous febuxostat (Form IX) further comprises the step of drying the febuxostat (Form IX) obtained in step (b) under vacuum.
According to another aspect, the present invention provides a crystalline form of febuxostat hydrate (Form XI) having an X-ray powder diffraction pattern with diffraction peaks at 2-theta values at about 4.9±0.1, 6.2±0.1, 6.8±0.1, 8.2±0.1, 9.7±0.1, 11.6±0.1, 12.2±0.1, 13.6±0.1, 15.8±0.1, 16.3±0.1, 17.5±0.1, 19.4±0.1, 20.5±0.1, 21.3±0.1, 21.5±0.1, 23.2±0.1, 24.8±0.1, 25.2±0.1, 25.8±0.1, 26.2±0.1, 26.8±0.1, 27.8±0.1, 29.2±0.1 and 29.8±0.1.
In one embodiment, the present invention provides a crystalline febuxostat hydrate (Form XI) having an X-ray powder diffraction pattern substantially as shown in
In certain embodiments, the present invention provides a process for preparing crystalline febuxostat hydrate (Form XI), the process comprising the steps of:
In some embodiments, the step of drying the precipitate is conducted at about 40° C.
It has unexpectedly been found that crystalline anhydrous febuxostat (Form IX) shows improved solubility at colon-simulated media (pHs=6.8-7.4) and intestinal fluids. As the major site of absorption for febuxostat is the colon, this suggests a possible improved bioavailability.
In certain embodiments, the present invention provides a pharmaceutical composition comprising as an active ingredient any one of the febuxostat forms of the present invention, and a pharmaceutically acceptable carrier. In one embodiment, the present invention provides a pharmaceutical composition comprising as an active ingredient the crystalline anhydrous febuxostat (Form IX) of the present invention, and a pharmaceutically acceptable carrier. In another embodiment, the pharmaceutical composition comprises as an active ingredient crystalline febuxostat NMP solvate (Form IV). In yet another embodiment, the pharmaceutical composition comprises as an active ingredient crystalline febuxostat NMP solvate (Form VI). In additional embodiments, the pharmaceutical composition comprises as an active ingredient crystalline febuxostat DMSO solvate (Form VII). In further embodiments, the pharmaceutical composition comprises as an active ingredient crystalline anhydrous febuxostat (Form VIII).
In further embodiments, the present invention provides a pharmaceutical composition comprising as an active ingredient a single crystalline febuxostat form of the present invention, and a pharmaceutically acceptable carrier. In one embodiment, the single crystalline febuxostat form is anhydrous febuxostat (Form IX). In other embodiments, the single crystalline febuxostat form is any one of forms IV, VI, VII or VIII. Each possibility represents a separate embodiment of the present invention.
In a particular embodiment, the pharmaceutical composition is in the form of a tablet.
In various embodiments, the present invention provides the pharmaceutical composition as disclosed herein for use in treating hyperuricaemia.
In some embodiments, the present invention provides a method of treating hyperuricaemia comprising administering to a subject in need thereof an effective amount of a pharmaceutical composition comprising any one of the febuxostat forms of the present invention. In particular embodiments, the present invention provides a method of treating hyperuricaemia comprising administering to a subject in need thereof an effective amount of a pharmaceutical composition comprising any one of febuxostat forms IX, IV, VI, VII or VIII of the present invention. Each possibility represents a separate embodiment of the present invention.
In certain embodiments, the subject is a mammal, for example a human.
In additional embodiments, the present invention provides the use of any one of the febuxostat forms of the present invention for treating hyperuricaemia. In further embodiments, the present invention provides the use of any one of febuxostat forms IX, IV, VI, VII or VIII of the present invention for treating hyperuricaemia. Each possibility represents a separate embodiment of the present invention.
Further embodiments and the full scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention is directed to novel crystalline forms of 2-(3-cyano-4-isobutoxyphenyl)-4-methyl-5-thiazolecarboxylic acid having structural formula (1).
The present invention is further directed to pharmaceutical compositions comprising the crystalline forms and a pharmaceutically acceptable carrier and their use in treating hyperuricaemia.
The present invention is further directed to methods of preparing the novel forms of febuxostat of the present invention.
Polymorphs are two or more solid state phases of the same chemical compound that possess different arrangement and/or conformation of the molecules. Different polymorphs of an active pharmaceutical compound can exhibit different physical and chemical properties such as color, stability, processability, dissolution and even bioavailability.
The identification and characterization of various polymorphs of a pharmaceutically active compound is therefore of great significance in obtaining medicaments with desired properties including a specific dissolution rate, milling properties, bulk density, thermal stability or shelf-life. The febuxostat forms of the present invention possess improved physicochemical characteristics including improved solubility at colon-simulated media and intestinal fluids (pH of 6.8-7.4). Furthermore, the febuxostat forms of the present invention are significantly less hygroscopic at the ICH recommended storage conditions and remain stable when stored over prolonged periods of time.
Provided herein is crystalline form of febuxostat hydrate (Form II) which is characterized by an X-ray diffraction pattern substantially as shown in
In some embodiments, the febuxostat (Form II) of the present invention is characterized by DSC and TGA profiles substantially as shown in
The present invention further provides a crystalline febuxostat NMP solvate (Form IV) which is characterized by an X-ray diffraction pattern substantially as shown in
In certain embodiments, the febuxostat NMP solvate (Form IV) of the present invention is characterized by DSC and TGA profiles substantially as shown in
Further provided herein is a crystalline febuxostat NMP solvate (Form VI) which is characterized by an X-ray diffraction pattern substantially as shown in
In various embodiments, the febuxostat NMP solvate (Form VI) of the present invention is characterized by DSC and TGA profiles substantially as shown in
The present invention further provides a crystalline febuxostat DMSO solvate (Form V) which is characterized by an X-ray diffraction pattern substantially as shown in any of
In some embodiments, the febuxostat DMSO solvate (Form V) of the present invention is characterized by a DSC profile substantially as shown in any of
The present invention further provides a crystalline febuxostat DMSO solvate (Form VII) which is characterized by an X-ray diffraction pattern substantially as shown in
In certain embodiments, the febuxostat DMSO solvate (Form VII) of the present invention is characterized by DSC and TGA profiles substantially as shown in
Provided herein is an anhydrous form of febuxostat (Form VIII) which is characterized by an X-ray diffraction pattern substantially as shown in
In various embodiments, the anhydrous febuxostat (Form VIII) of the present invention is characterized by DSC and TGA profiles substantially as shown in
The present invention further provides an anhydrous form of febuxostat (Form IX) which is characterized by an X-ray diffraction pattern substantially as shown in any of
In certain embodiments, the anhydrous febuxostat (Form IX) of the present invention is characterized by a DSC profile substantially as shown in any of
The present invention further provides a crystalline febuxostat hydrate (Form XI) which is characterized by an X-ray diffraction pattern substantially as shown in
In various embodiments, the febuxostat hydrate (Form XI) of the present invention is characterized by a DSC profile substantially as shown in
The present invention further provides processes for the preparation of the febuxostat forms of the present invention. The processes include thermal precipitations and precipitations from supersaturated solutions. In particular, these processes involve the use of febuxostat, for example febuxostat API as the starting material or any other commercially available febuxostat or febuxostat prepared by any methods known in the art, including, for example, the methods described in EP 0513379, JP 1993500083, U.S. Pat. No. 5,614,520 and WO 92/09279, JP 10-045733, JP10-139770, JP 1994345724 (JP 6-345724), in publications in Heterocycles, 1998, 47: 857-864 and Org. Lett., 2009, 11(8): 1733-1736 and in PCT international patent application PCT/IL2010/000807. The contents of the aforementioned references are incorporated by reference herein. According to one embodiment, the febuxostat starting material is heated until a melt is obtained, preferably under vacuum followed by controlled precipitation by slow/fast cooling. According to another embodiment, the febuxostat starting material is dissolved in a suitable solvent or a mixture of solvents to prepare saturated solutions at room temperatures or at temperatures below the solvent boiling point. The solvent is then removed by evaporation. In additional embodiments, the febuxostat starting material is dissolved in one solvent followed by the addition of an anti-solvent to afford the precipitation of a febuxostat form of the present invention. In further embodiments, the febuxostat starting material is dissolved in a solvent or a mixture of solvents while heated. The hot solution is then cooled to afford the precipitation of a febuxostat form of the present invention.
Additional methods for the preparation of the febuxostat forms of the present invention include, for example, precipitation from a suitable solvent, precipitation by cooling under vacuum, sublimation, growth from a melt, solid state transformation from another phase, precipitation from a supercritical fluid, and jet spraying. Techniques for precipitation from a solvent or solvent mixture include, for example, evaporation of the solvent, decreasing the temperature of the solvent mixture, freeze-drying the solvent mixture, and addition of anti-solvents (counter-solvents) to the solvent mixture. The term “anti-solvent” as used herein refers to a solvent in which the compound has low solubility.
Suitable solvents and anti-solvents for preparing the forms of the present invention include polar and non-polar solvents. The choice of solvent or solvents is typically dependent upon one or more factors, including the solubility of the compound in such solvent and vapor pressure of the solvent. Combinations of solvents may be employed; for example, the compound may be solubilized into a first solvent followed by the addition of an anti-solvent to decrease the solubility of the compound in the solution and to induce precipitation. Suitable solvents include, but are not limited to, polar aprotic solvents, polar protic solvents, and mixtures thereof. Particular examples of suitable polar protic solvents include, but are not limited to, alcohols such as methanol (MeOH), ethanol (EtOH), 1-butanol, and isopropanol (IPA). Particular examples of suitable polar aprotic solvents include, but are not limited to, acetonitrile (ACN), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), N-methyl-2-pyrrolidone (NMP), dichloromethane, acetone, dimethylformamide (DMF), and dimethylsulfoxide (DMSO). Each possibility represents a separate embodiment of the present invention.
The febuxostat forms of the present invention may be obtained by distillation or solvent addition techniques such as those known to those skilled in the art. Suitable solvents for this purpose include any of those solvents described herein, including protic polar solvents, such as alcohols (including those listed above), aprotic polar solvents (including those listed above), ketones (for example, acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone) and also esters (ethyl acetate (EtOAc)). Each possibility represents a separate embodiment of the present invention.
Exemplary processes used to prepare each of the febuxostat forms of the present invention are provided herein.
Methods for “precipitation from solution” include, but are not limited to, evaporation of a solvent or solvent mixture, a concentration method, a slow cooling method, a fast cooling method, a reaction method (diffusion method, electrolysis method), a hydrothermal growth method, a fusing agent method, and so forth. The solution can be a saturated solution or a supersaturated solution, optionally heated to temperatures below the solvent boiling point. The recovery of the forms can be done for example, by filtering the suspension and drying. Alternatively, the solvents may be removed by rotary evaporation at desired temperatures.
The febuxostat forms of the present invention can be prepared using fast/slow precipitation from saturated solutions in different solvents or mixture of solvents which are allowed to evaporate, preferably at room temperatures. The obtained precipitate may further by washed with a suitable solvent (e.g. ACN). In additional embodiments, the obtained precipitate may further be dried at room temperatures or at temperatures below the solvent boiling point (e.g. 40° C.), preferably under vacuum. Alternatively, the saturated solutions can be heated followed by their cooling to induce precipitation as is known in the art.
The febuxostat forms of the present invention can be prepared using solvent/anti-solvent systems. Typically the active ingredient is dissolved in a suitable solvent, optionally at temperatures below the solvent boiling point. An anti-solvent is then added to induce precipitation of the desired form.
The febuxostat forms of the present invention can be prepared by melting the active ingredient, preferably in an inert atmosphere. The melt is then cooled to afford precipitation of the desired form.
The febuxostat forms of the present invention can be prepared by the slurry method as is well known in the art. Suspensions of the active ingredient in different solvents or mixture of solvents are prepared and shaken for long intervals (typically 24 hours).
Within the scope of the present invention are high pressure techniques where the active ingredient is compressed using various forces (e.g. grinding) as is known in the art.
As contemplated herein, the febuxostat forms of the present invention can further be obtained using lyophilization wherein the compound is dissolved in water, followed by a freeze-drying procedure.
The novel forms of the present invention are useful as pharmaceuticals for treating hyperuricaemia. The present invention thus provides pharmaceutical compositions comprising any of the febuxostat forms disclosed herein and a pharmaceutically acceptable carrier. The forms of the present invention can be safely administered orally or non-orally. Routes of administration include, but are not limited to, oral, topical, mucosal, nasal, parenteral, gastrointestinal, intraspinal, intraperitoneal, intramuscular, intravenous, intrauterine, intraocular, intradermal, intracranial, intratracheal, intravaginal, intracerebroventricular, intracerebral, subcutaneous, ophthalmic, transdermal, rectal, buccal, epidural and sublingual. Each possibility represents a separate embodiment of the invention. Typically, the febuxostat forms of the invention are administered orally. The pharmaceutical compositions can be formulated as tablets (including e.g. film-coated tablets), powders, granules, capsules (including soft capsules), orally disintegrating tablets, and sustained-release preparations as is well known in the art. Each possibility represents a separate embodiment of the invention.
Pharmacologically acceptable carriers that may be used in the context of the present invention include various organic or inorganic carriers including, but not limited to, excipients, lubricants, binders, disintegrants, water-soluble polymers and basic inorganic salts. The pharmaceutical compositions of the present invention may further include additives such as, but not limited to, preservatives, antioxidants, coloring agents, sweetening agents, souring agents, bubbling agents and flavorings.
Suitable excipients include e.g. lactose, D-mannitol, starch, cornstarch, crystalline cellulose, light silicic anhydride and titanium oxide. Suitable lubricants include e.g. magnesium stearate, sucrose fatty acid esters, polyethylene glycol, talc and stearic acid. Suitable binders include e.g. hydroxypropyl cellulose, hydroxypropylmethyl cellulose, crystalline cellulose, a-starch, polyvinylpyrrolidone, gum arabic powder, gelatin, pullulan and low-substitutional hydroxypropyl cellulose. Suitable disintegrants include e.g. crosslinked povidone (any crosslinked 1-ethenyl-2-pyrrolidinone homopolymer including polyvinylpyrrolidone (PVPP) and 1-vinyl-2-pyrrolidinone homopolymer), crosslinked carmellose sodium, carmellose calcium, carboxymethyl starch sodium, low-substituted hydroxypropyl cellulose, cornstarch and the like. Suitable water-soluble polymers include e.g. cellulose derivatives such as hydroxypropyl cellulose, polyvinylpyrrolidone, hydroxypropylmethyl cellulose, methyl cellulose and carboxymethyl cellulose sodium, sodium polyacrylate, polyvinyl alcohol, sodium alginate, guar gum and the like. Suitable basic inorganic salts include e.g. basic inorganic salts of sodium, potassium, magnesium and/or calcium. Particular embodiments include the basic inorganic salts of magnesium and/or calcium. Basic inorganic salts of sodium include, for example, sodium carbonate, sodium hydrogen carbonate, disodiumhydrogenphosphate, etc. Basic inorganic salts of potassium include, for example, potassium carbonate, potassium hydrogen carbonate, etc. Basic inorganic salts of magnesium include, for example, heavy magnesium carbonate, magnesium carbonate, magnesium oxide, magnesium hydroxide, magnesium metasilicate aluminate, magnesium silicate, magnesium aluminate, synthetic hydrotalcite, aluminahydroxidemagnesium and the like. Basic inorganic salts of calcium include, for example, precipitated calcium carbonate, calcium hydroxide, etc.
Suitable preservatives include e.g. sodium benzoate, benzoic acid, and sorbic acid. Suitable antioxidants include e.g. sulfites, ascorbic acid and a-tocopherol. Suitable coloring agents include e.g. food colors such as Food Color Yellow No. 5, Food Color Red No. 2 and Food Color Blue No. 2 and the like. Suitable sweetening agents include e.g. dipotassium glycyrrhetinate, aspartame, stevia and thaumatin. Suitable souring agents include e.g. citric acid (citric anhydride), tartaric acid and malic acid. Suitable bubbling agents include e.g. sodium bicarbonate. Suitable flavorings include synthetic substances or naturally occurring substances, including e.g. lemon, lime, orange, menthol and strawberry.
In some embodiments, the present invention provides a pharmaceutical composition comprising as an active ingredient a single crystalline form of febuxostat of the present invention (e.g. the anhydrous febuxostat (Form IX) or any one of forms IV, VI, VII or VIII) and a pharmaceutically acceptable carrier. In certain embodiments, the pharmaceutically acceptable carrier comprises an excipient such as lactose, crystalline cellulose and starch, a binder such as hydroxypropyl cellulose, coating such as polyethylene glycol, a disintegrant such as carmellose, hydroxypropyl cellulose and crosspovidone and other known binders, lubricants, coating agents, plasticizers, diluents, colorants, and preservatives as defined hereinabove.
The febuxostat forms of the present invention are particularly suitable for oral administration in the form of tablets, capsules, pills, dragées, powders, granules and the like. A tablet may be made by compression or molding, optionally with one or more excipients as is known in the art. Specifically, molded tablets may be made by molding in a suitable machine a mixture of the powdered active ingredient moistened with an inert liquid diluent.
The tablets and other solid dosage forms of the pharmaceutical compositions described herein may optionally be scored or prepared with coatings and shells, such as enteric coatings and other coatings well known in the art. They may also be formulated so as to provide slow or controlled release of the active ingredient therein using, for example, hydroxypropylmethyl cellulose in varying proportions to provide the desired release profile, other polymer matrices and the like. The active ingredient can also be in micro-encapsulated form, if appropriate, with one or more of the above-described excipients.
The present invention provides a method of treating hyperuricaemia comprising administering to a subject in need thereof an effective amount of a composition comprising any one of the febuxostat forms of the present invention.
“A therapeutically effective amount” as used herein refers to an amount of an agent which is effective, upon single or multiple dose administration to the subject in providing a therapeutic benefit to the subject. In additional embodiments, the febuxostat forms of the present invention are used for the preparation of a medicament for treating hyperuricaemia.
The present invention further provides the administration of the febuxostat forms in combination therapy with one or more other active ingredients. The combination therapy may include the two or more active ingredients within a single pharmaceutical composition as well as the two or more active ingredients in two separate pharmaceutical compositions administered to the same subject simultaneously or at a time interval determined by a skilled artisan.
The principles of the present invention are demonstrated by means of the following non-limiting examples.
1. Reagents
Febuxostat API was manufactured according to the teachings of Hasegawa in Heterocycles 47, 857-64, 1998.
Acetic acid, AR, Jiangsu Qiangsheng chemical reagents, Lot No. 20100221
Acetonitrile, HPLC grade, Sigma, Lot No. 07278PH or Merck, Lot No. SB0SF60081
Ammonium hydrogen carbonate, AR, Shanghai Shisihewei chemical, Lot No. 1007101
Ethanol, HPLC grade, Sigma, Lot No. 11085CH
DMF, HPLC grade, Merck, Lot No. SB0S600093
DMSO, HPLC grade, Sigma, Lot No. 05737BH or 27496kk
Hydrochloric acid, AR, SCRC, Lot No. T20100302
Methanol, AR, SCRC, Lot No. T20090912 or HPLC grade, Merck, Lot No. SB0SF60085
Ethanol Acetate, AR, Yixing Secondary Chemical Company, Lot No. 090607 or SCRC, Lot No. T20100126
Isopropyl alcohol, AR, Sinopharm Chemical Reagent Co. Ltd, Lot No. T20090813
Acetone, AR, Sinopharm Chemical Reagent Co. Ltd, Lot No. 090104
THF, AR, Yixing Secondary Chemical, Lot No. 090901 or HPLC grade, Merck, Lot No. IL8IF58153
1-Butanol, AR, SCRC, Lot No. T20080818
Lecithin, laboratory grade, Fisher chemical, Lot No. 091043
MEK, AR, SCRC, Lot No. T20090724
2-Me-THF, AR, Shanghai Jiachen Chemical Reagent Co. Ltd, Lot No. 090323
N-methylpyrrolidone, HPLC grade, Sigma-Aldrich, Lot No. S86863-279
Monobasic potassium phosphate, AR, SCRC, Lot No. F20100413
Potassium biphthalate, GR, Shanghai experimental reagents, Lot No. 070423
Potassium chloride, AR, SCRC, Lot No. F20090409
Sodium dihydrogen phosphate, AR, SCRC, Lot No. F20100330
Sodium hydroxide, AR, Shanghai Lingfeng chemical reagents, Lot No. 081118
Sodium lauryl sulfate, AR, SCRC, Lot No. F20080521
Sodium taurocholate, laboratory grade, Sigma, Lot No. 0001428479
Sodium chloride, AR, Jiangsu Qiangsheng chemical reagents, Lot No. 20100112
2. Instruments
SMS DVS
Agilent 1200 HPLC
Mettler Toledo Seven Multi pH meter
Binder KBF115 Stability Chamber
GZX-9140 MBE oven
ERWEKA SVM203 Tapped Density Tester
Sartorius CP 225D Balance
Mettler Toledo MX5 Balance
ELGA Water Purification Equipment
Mettler Toledo DSC 1
Mettler Toledo TGA/DSC 1
Rigaku D/MAX 2200 X-ray powder diffractometer
Thermo Nicolet 380 FT-IR
NMR Varian 400
Nikon LV100 Polarized Light Microscopy
Boxun vacuum oven DZF-6050
Eyela FDU-1100 freeze dryer
Jobin Yvon LabRam-1B FT-Raman
3. XRPD, DSC, TGA, FTIR, FT-Raman and HPLC Methods
3.1 XRPD Method
Details of XRPD method used in the tests are mentioned below:
3.2 DSC and TGA Methods
Details of DSC method used in the tests are mentioned below:
Details of DSC (topem) method used in the tests are mentioned below:
Details of TGA method used in the tests are mentioned below:
Heat from 30° C. to 400° C. at 10° C./min
3.3 FT-IR and FT-Raman Method
Details of FT-IR method used in the tests are mentioned below:
Details of FT-Raman method used in the tests are mentioned below:
3.4 HPLC Method
Details of HPLC method used in the tests are mentioned below:
The detailed chromatographic conditions are listed hereinbelow. The typical retention time of febuxostat main peak is 8.2 min.
4. General Preparation Methods
4.1 Method 1: Slow Precipitation from Saturated Solutions
Solutions of Febuxostat API (lot number CCS-1058/B361/B-IV/06) in different solvents were prepared and filtered through 0.22 μm filter into clean vessels. Solvents were evaporated at room temperatures to form crystals. Febuxostat hydrate (Form II) was identified by this method, as set forth in the Examples below.
4.2 Method 2: Solvent-Thermal Heating/Cooling
Saturated solutions of Febuxostat API (lot number CCS-1058/B361/B-IV/06) in different solvents or mixture of solvents were prepared at 50° C. The solutions were then cooled down at 5° C. to form crystals. Febuxostat Form IV (NMP solvate) and febuxostat Form V (DMSO solvate) were identified by this method, as set forth in the Examples below.
4.3 Method 3: Anti-Solvent Precipitation
Saturated solutions of Febuxostat API (lot number CCS-1058/B361/B-IV/06) with different solvents were prepared at 25/50° C. An anti-solvent (kept at 25° C.) was then added to precipitate out crystals. Febuxostat Form VI (NMP solvate) and febuxostat Form VII (DMSO solvate) were identified by this method, as set forth in the Examples below.
4.4 Method 4: Thermal Heating/Cooling
Febuxostat API (lot number CCS-1058/B361/B-IV/06) was heated to melt under vacuum. The melted compound was then rapidly or slowly cooled. Anhydrous febuxostat Form VIII was identified by this method, as set forth in the Examples below.
4.5 Method 5: Fast Precipitation from Saturated Solutions
Saturated solutions of febuxostat API (lot number CCS-1058/B361/B-IV/06) were prepared with different solvents at room temperatures. The solvents were then removed by rotary evaporator below 50° C. Anhydrous febuxostat Form IX was identified by this method, as set forth in the Examples below.
4.6 Method 6: Slow Precipitation from Saturated Solutions Followed by Drying
A clear solution of febuxostat API (lot number CCS-1058/B361/B-IV/06) in THF was prepared. The THF was then evaporated in fume hood at room temperature and the residual solid was further dried in a vacuum oven at 40° C. overnight. Febuxostat hydrate (Form XI) was identified by this method, as set forth in the Examples below.
5. General Assessment Methods
5.1 Hygroscopicity Measurements
The sorption/desorption profiles of the forms of the present invention were tested at 25° C. under 0-90% relative humidity. The forms of the present invention were classified according to the following criteria:
Deliquescent: Sufficient water is absorbed to form a liquid.
Very hygroscopic: Increase in mass is equal to or greater than 15%.
Hygroscopic: Increase in mass is less than 15% and equal to or greater than 2%.
Slightly hygroscopic: Increase in mass is less than 2% and equal to or greater than 0.2%.
Non-hygroscopic: Increase in mass is less than 0.2%.
5.2 Aqueous Solubility Measurements
Testing media: water, pH 1.2, 4.5, 6.8, 7.4 USP buffers, 0.01 N HCl, 0.1 N HCl, SGF, FaSSIF, FeSSIF.
The various testing media were prepared as follows:
pH 1.2 (USP): 50 mL of 0.2 M potassium chloride solution were placed in a 200 mL volumetric flask to which 85.0 mL of 0.2M hydrochloric acid solution were added followed by the addition of water to obtain the required volume.
pH 4.5 (USP): 50 mL of 0.2 M potassium biphthalate solution were placed in a 200 mL volumetric flask to which 8.8 mL of 0.2 M sodium hydroxide solution were added followed by the addition of water to obtain the required volume.
pH 6.8 (USP): 50 mL of 0.2 M monobasic potassium phosphate solution were placed in a 200 mL volumetric flask to which 22.4 mL of 0.2 M sodium hydroxide solution were added followed by the addition of water to obtain the required volume.
pH 7.4 (USP): 50 mL of 0.2 M monobasic potassium phosphate solution were placed in a 200 mL volumetric flask to which 39.1 mL of 0.2 M sodium hydroxide solution were added followed by the addition of water to obtain the required volume.
Simulated gastric fluid (SGF): 0.01 N HCl, 0.05% sodium lauryl sulfate, and 0.2% NaCl.
Fasted state simulated intestinal fluid (FaSSIF): 29 mM NaH2PO4, 3 mM Na taurocholate, 0.75 mM lecithin, 103 mM NaCl, and NaOH to obtain pH 6.5.
Fed state simulated intestinal fluid (FeSSIF): 144 mM acetic acid, 15 mM Na taurocholate, 3.75 mM lecithin, 204 mM NaCl, and NaOH to obtain pH 5.0.
Testing procedure: The tested febuxostat form was placed in each of the different media and was kept shaken for 24 hours at 25° C. Then, the saturated solution was filtered. The concentration of the febuxostat form in filtrate was determined by HPLC. The final pH was then tested. The test was conducted in duplication.
5.3 Solid Stability Measurements
Testing conditions: 40° C., 60° C., 40° C./RH 75%, 60° C./RH 75%, light
Testing procedure: About 3 mg of a febuxostat form were weighed in a glass vial and stored under the different conditions for 1 week and 2 weeks, separately. The same febuxostat form was stored at −20° C. as control. The test was conducted in duplication. The physical appearance, assay and total related substances of each of the febuxostat forms were measured by HPLC at the end of the first and second weeks.
5.4 Physical Stability Measurements
Testing conditions: 40° C., 60° C., 40° C./RH 75%, 60° C./RH 75%, light
Testing procedure: About 50 mg of a febuxostat form were weighed in glass vial for testing the physical stability and were stored under different conditions for 1 week and 2 weeks, separately. The same febuxostat form was stored at −20° C. as control. XRPD, DSC and TGA of each of the febuxostat forms were measured at the end of the first and second weeks.
5.5 Bulk and Tapped Density Measurements
Bulk density testing: A febuxostat form in an amount which is sufficient to complete the test was passed through a 1.0 mm (No. 18) screen to break up agglomerates that may have formed during storage. The febuxostat form was then weighed (M) and the powder was added into a 10 mL graduated cylinder. The powder was carefully leveled without compacting, and the unsettled apparent volume, Vo, was read. The bulk density, in g per mL, was calculated by the formula:
Bulk Density=M/Vo
Tapped density testing: A febuxostat form in an amount which is sufficient to complete the test was passed through a 1.0 mm (No. 18) screen to break up agglomerates that may have formed during storage. The febuxostat form was then weighed and the powder was added into a 10 mL graduated cylinder. The powder was carefully leveled without compacting. The cylinder was tapped 500 times initially and the tapped volume, Va, was measured to the nearest graduated unit. The tapping was then repeated for additional 750 times and the tapped volume, Vb, was measured to the nearest graduated unit. If the difference between the two volumes was less than 2%, Vb was taken as the final tapped volume, Vf. The tapped density, in g per mL, was calculated by the formula:
Tapped Density=M/Vf
General method 1 was performed. Thus, febuxostat API was dissolved in the following solvents/solvent mixtures: THF; THF:MeOH=1:1 (v/v); THF:EtOH=1:1 (v/v); THF:IPA=1:1 (v/v); THF:1-Butanol=1:1 (v/v) or THF:iPrOAc=1:1 (v/v). The solutions were then filtered through 0.22 μm filter into clean vessels. The solvents/solvent mixtures were evaporated at room temperatures to form febuxostat Form II. This polymorphic form was characterized by X-ray diffraction (
General method 2 was performed. Thus, febuxostat API was dissolved in the following solvents/mixture of solvents: NMP; 2-MeTHF:NMP=1:1 (v/v); DMF:NMP=1:1 (v/v); or NMP:THF=1:1 (v/v) at 50° C. The solutions were then cooled down at 5° C. to form crystals. Febuxostat NMP solvate (Form IV) has a molar ratio of 1:0.2 febuxostat:NMP. Febuxostat NMP solvate (Form IV) was characterized by X-ray diffraction (
General method 3 was performed. Thus, febuxostat API was dissolved in NMP to form a saturated solution at 25 or 50° C. An anti-solvent (either water or ACN) that was kept at 25° C. was then added to precipitate out crystals. The febuxostat NMP solvate prepared by this method has molar ratio of 1:0.5 febuxostat: NMP. Febuxostat NMP solvate (Form VI) was characterized by X-ray diffraction (
General method 2 was performed. Thus, febuxostat API was dissolved in the following solvents/mixture of solvents: DMSO; 2-MeTHF:DMSO=1:1 (v/v); DMF:DMSO=1:1 (v/v); or NMP:DMSO=1:1 (v/v) at 50° C. The solutions were then cooled down at 5° C. to form crystals. Febuxostat DMSO solvate (Form V) has a molar ratio of 1:0.6 febuxostat:DMSO. Febuxostat DMSO solvate (Form V) was characterized by X-ray diffraction (
When scaling up the preparation of the febuxostat DMSO solvate (Form V), about 1 g of febuxostat API was weighed into a vial. 1 mL of DMF:DMSO=1:1 was added followed by sonication for 5 minutes at 50° C. to form a clear solution. The solution was stored at room temperature for 30 minutes to form a precipitate. The residual solid was then separated by vacuum filtration and washed with ACN, followed by drying using a vacuum oven at 40° C. overnight. The febuxostat DMSO solvate (Form V) was characterized using X-ray powder diffraction (
General method 3 was performed. Thus, febuxostat API was dissolved in DMSO to form a saturated solution at 25 or 50° C. Water at 25° C. was then added as an anti-solvent to afford the precipitation of crystals. The febuxostat DMSO solvate prepared by this method has molar ratio of 1:0.8 febuxostat:DMSO. Febuxostat DMSO solvate (Form VII) was characterized by X-ray diffraction (
General method 4 was performed. Thus, febuxostat API was heated to melt under vacuum. The melted compound was then rapidly or slowly cooled to afford the formation of febuxostat (Form VIII). Anhydrous febuxostat (Form VIII) was characterized by X-ray diffraction (
General method 5 was performed. Thus, febuxostat API was dissolved in the following solvents: MeOH, MEK, acetone or EtOAc at room temperatures. The solvents were then removed by rotary evaporator below 50° C. Anhydrous febuxostat (Form IX) was characterized by X-ray diffraction (
When scaling up the preparation of anhydrous febuxostat (Form IX), about 1.3 g of febuxostat API were weighed into a round flask to which 20 ml of EtOAc were added followed by sonication for 5 minutes at room temperature to form a clear solution. The solvent was then removed by rotary evaporation below 50° C. The residual solid was dried using a vacuum oven at 40° C. overnight. The anhydrous febuxostat (Form IX) was characterized by X-ray diffraction (
General method 6 was performed. Thus, about 1.2 g of febuxostat API were weighed into a vial. 20 ml of THF were then added. The vial was shaken by hand to form a clear solution. The THF was slowly evaporated in a fume hood at room temperature. The residual solid was further dried in a vacuum oven at 40° C. overnight.
Febuxostat hydrate (Form XI) was characterized by X-ray diffraction (
Febuxostat forms V, IX and XI prepared according to Examples 5 (scale-up), 8 (scale-up) and 9, respectively, were characterized for assessing their physical and chemical properties and were further compared with Form G of U.S. Pat. No. 6,225,474.
The DVS isotherm plots of the febuxostat forms are shown in
Febuxostat Forms V, IX and XI of the present invention show good solubility in pH6.8 USP buffer, pH7.4 USP buffer, FaSSIF, FeSSIF and show poor solubility in pH1.2 USP buffer, 0.01N HCl, 0.1N HCl and SGF (Table 10; aqueous solubility). Without being bound by any theory or mechanism of action, the improved solubility of the febuxostat forms of the present invention in basic media suggests better febuxostat absorption is the colon where the pH ranges form 6.8 to 7.4. As the major site of febuxostat absorption is the colon, the solubility measurements imply improved bioavailability of the febuxostat polymorphs of the present invention.
The solid stability of the febuxostat forms of the present invention under various conditions was measured and the results are summarized in Tables 11-13. The assay and TRS of febuxostat DMSO solvate (Form V), anhydrous febuxostat (Form IX), and febuxostat hydrate (Form XI) show no significant change under different conditions (40° C., 60° C., 40° C./75% RH, 60° C./75% RH) at end of the first and second weeks. When stored under light the recovery of all of the forms at end of the first and second week was 92.8%-97.5%, and the TRS increased by 1.7%-6.5%.
The physical stability of the febuxostat forms of the present invention under various conditions (40° C., 60° C., 40° C./75% RH, 60° C./75% RH and light) at end of the first and second weeks was further measured using XRPD, DSC and TGA. Febuxostat forms V, IX and XI of the present invention were stable under 40° C., 60° C. and light at the end of the first and second week. Febuxostat DMSO solvate (Form V) partially converted to form G of U.S. Pat. No. 6,225,474 under 40° C./75% RH at the end of the first week and completely converted to form G of U.S. Pat. No. 6,225,474 under 40° C./75% RH at the end of the second week. Anhydrous febuxostat (Form IX) partially converted to form G of U.S. Pat. No. 6,225,474 under 40° C./75% RH at the end of second week. Forms V, IX and XI completely converted to form G of U.S. Pat. No. 6,225,474 under 60° C./75% RH at the end of the first and second weeks. Febuxostat hydrate (Form XI) completely converted to form G of U.S. Pat. No. 6,225,474 under 40° C./75% RH at the end of the first and second weeks.
The bulk and tapped density of febuxostat forms V, IX and XI of the present invention were measured and compared to form G of U.S. Pat. No. 6,225,474. The results are summarized in Table 14.
Anhydrous febuxostat (Form IX) of the present invention has the lowest bulk and tapped densities and can thus be easily formulated as tablets. Febuxostat forms V and XI have adequate bulk and tapped densities which allow for easy incorporation into a variety of different formulations.
About 200 mg of febuxostat API were weighed into a vial. 400 μL of DMF:DMSO=1:1 were added into the vial followed by 5 minutes sonication at 50° C. to obtain a clear solution. The solution was stored at room temperature for 30 minutes with no crystal precipitation. About 1 mg of febuxostat DMSO solvate (Form V) was added and precipitation occurred. The mixture was sonicated for 5 minutes at 50° C. to obtain a clear solution. The solution was stored at room temperature for 4-5 days. A single crystal of febuxostat DMSO solvate (Form V) was formed. The single crystal was first analyzed by XRPD (
About 100 g of anhydrous febuxostat (Form IX) are mixed with about 300 g of lactose, 100 g of starch and 10 g of hydroxypropyl cellulose. The mixture is then charged into a mixer granulator with addition of DDW quantum satis to obtain granules which are consequently dried in a fluid bed drier at 60° C. The produced granules are sieved to remove particles having a size larger than 700 microns. The sieved granules are mixed with 25 g of crosscarmellose sodium and 5 g of magnesium stearate in a cross rotary mixer to obtain the lubricated granules. The lubricated granules are tableted with a rotary type tableting machine using a tableting pressure of 2,500 kgf/cm3.
While the present invention has been particularly described, persons skilled in the art will appreciate that many variations and modifications can be made. Therefore, the invention is not to be construed as restricted to the particularly described embodiments, and the scope and concept of the invention will be more readily understood by reference to the claims, which follow.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IL11/00258 | 3/17/2011 | WO | 00 | 4/24/2013 |
| Number | Date | Country | |
|---|---|---|---|
| 61407465 | Oct 2010 | US |
