DESC:FORM 2

THE PATENTS ACT 1970
(SECTION 39 OF 1970)

&

THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(Section 10 and Rule 13)

NOVEL SOLVATES OF FARNESOID X RECEPTOR (FXR) AGONIST

We, VIRUPAKSHA ORGANICS LIMITED,
a company incorporated under the companies act, 1956 having address at
B-4, IDA, Gandhinagar, Hyderabad; Telangana State – 500037, India

The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention relates to novel solvates of Farnesoid x receptor (FXR) agonist.

The present invention particularly relates to novel solvates of Obeticholic acid.

The present invention particularly relates to novel hydrocarbon solvates of Obeticholic acid.

The present invention more particularly relates to cyclohexane solvate of Obeticholic acid and a process for its preparation.

BACKGROUND OF THE INVENTION
Obeticholic acid is a farnesoid X receptor (FXR) agonist. Chemically, Obeticholic acid is 3a,7a-dihydroxy­6a-ethyl-5ß-cholan-24-oic acid. It is a white to off-white powder. It is soluble in methanol, acetone and ethyl acetate. Its solubility in water is pH dependent. It is slightly soluble at low pH and very soluble at high pH. Its chemical formula is C26H44O4, the molecular weight is 420.63 g/mol and the chemical structure is:

Obeticholic acid was approved for the treatment of primary biliary cholangitis (PBC) in combination with ursodeoxycholic acid (UDCA) in adults with an inadequate response to UDCA, or as monotherapy in adults unable to tolerate UDCA. Obeticholic acid is marketed by Intercept Pharmaceuticals under the brand name OCALIVA.

US Patent No. 7,138,390 discloses Obeticholic acid for the first time. This patent also discloses process for preparing Obeticholic acid by treating 3a-hydroxy-7-keto-5ß-cholan-24-oic acid with 3,4-dihydro-2H-pyrane to give 3a-tetrahydropyranyloxy-7-keto-5ß-cholan-24-oic acid followed by alkylation, reduction and hydrolysis to give Obeticholic acid. The process is shown in the scheme given below:

Scheme I

International (PCT) Publication WO 2013/192097A1 discloses crystalline Forms of Obeticholic acid like Form-1 (non-crystalline), Form A, Form C, Form D, Form F, Form G and Form I.

Different salts and solid state forms (including solvated forms) of an active pharmaceutical ingredient may possess different properties. Such variations in the properties of different salts and solid state forms and solvates may provide a basis for improving formulation, for example, by facilitating better processing or handling characteristics, improving the dissolution profile, or improving stability (polymorph as well as chemical stability) and shelf-life. These variations in the properties of different salts and solid state forms may also provide improvements to the final dosage form, for instance, if they serve to improve bioavailability. Different salts and solid state forms and solvates of an active pharmaceutical ingredient may also give rise to a variety of polymorphs or crystalline forms, which may in turn provide additional opportunities to use variations in the properties and characteristics of a solid active pharmaceutical ingredient for providing an improved product.

Discovering new salts, solid state forms and solvates of a pharmaceutical product can provide materials having desirable processing properties, such as ease of handling, ease of processing, storage stability, and ease of purification or as desirable intermediate crystal forms that facilitate conversion to other salts or polymorphic forms. New salts, polymorphic forms and solvates of a pharmaceutically useful compound can also provide an opportunity to improve the performance characteristics of a pharmaceutical product (dissolution profile, bioavailability, etc.). It enlarges the repertoire of materials that a formulation scientist has available for formulation optimization, for example by providing a product with different properties, e.g., a different crystal habit, low content of residual solvent, a lower degree of hygroscopicity, higher crystallinity or polymorphic stability which may offer better processing or handling characteristics, improved dissolution profile, or improved shelf-life. For at least these reasons, there is a need for additional salts and solid state forms (including solvated forms) of Obeticholic acid, particularly those having improved solubility and/or dissolution characteristics.

Considering the commercial importance of Obeticholic acid, applicant focused on developing novel solvates of Obeticholic acid which is thermally, physically and chemically stable. We have now found that solvates of Obeticholic acid can be prepared, which are substantially bulk stable.

Solvates are crystalline solid adducts containing either stoichiometric or nonstoichiometric amounts of a solvent incorporated within the crystal structure and are rarely used in pharmaceuticals because the solvents are usually volatile thus making it difficult to maintain the solvent in the crystal. If one were to desolvate a pharmaceutical solvate or if it desolvated due to storage conditions or otherwise, it could lead to the formation of multiple polymorphs or complete collapse of the crystal structure, forming an amorphous compound with different physical properties. Obviously, this batch-to-batch variability and questionable shelf life is undesired. Typically people find solvates of common solvents. Cyclohexane solvate of the present invention desolvate only at considerably higher temperatures and harsher conditions than traditional solvates. Cyclohexane solvate is also pharmaceutically acceptable in much larger amounts than one would expose people to with a traditional solvate. Thus, the Cyclohexane solvate of the present invention have characteristics that are vastly superior to traditional solvates.

OBJECTIVE OF THE INVENTION
The main objective of the present invention is to provide novel solvates of Farnesoid x receptor (FXR) agonist.

The preferred objective of the present invention is to provide novel solvates of Obeticholic acid.

Another preferred objective of the present invention is to provide novel hydrocarbon solvates of Obeticholic acid.

Yet another preferred objective of the present invention is to provide cyclohexane solvate of Obeticholic acid and a process for its preparation.

Yet another preferred objective of the present invention is to provide cyclohexane solvate of Obeticholic acid which is highly stable.

Still yet another preferred objective of the present invention is to provide pharmaceutical composition comprising cyclohexane solvate of Obeticholic acid.

SUMMARY OF THE INVENTION
Accordingly, the present invention provides novel solvates of Obeticholic acid.

In a preferred aspect, the present invention provides novel hydrocarbon solvates of Obeticholic acid.

In another preferred aspect, the present invention provides cyclohexane solvate of Obeticholic acid.

In yet another preferred aspect, the present invention provides cyclohexane solvate of Obeticholic acid which is characterized by X-ray diffraction pattern having peaks at about 4.2, 5.7, 15.5 and 16.2 ± 0.2 degrees 2?.

In yet another preferred aspect, the present invention provides cyclohexane solvate of Obeticholic acid which is characterized by X-ray diffraction pattern substantially as shown in Fig. 1.

In yet another preferred aspect, the present invention provides cyclohexane solvate of Obeticholic acid which is further characterized by 1H-NMR spectrum as shown in Figs. 2, 3 and 4.

In yet another preferred aspect, the present invention provides a process for the preparation of novel solvates of Obeticholic acid, which comprises the steps of:
a) adding Obeticholic acid to a solvent or a mixture of solvent, and
b) isolating the novel solvates of Obeticholic acid.

In yet another preferred aspect, the present invention provides a process for the preparation of novel hydrocarbon solvates of Obeticholic acid, which comprises the steps of:
a) adding Obeticholic acid to a hydrocarbon solvent, and
b) isolating the novel solvates of Obeticholic acid.

In yet another preferred aspect, the present invention provides a process for the preparation of novel hydrocarbon solvates of Obeticholic acid, which comprises the steps of:
a) adding Obeticholic acid to a solvent,
b) adding hydrocarbon solvent to the step a) solution, and
c) isolating the novel solvates of Obeticholic acid.

In yet another preferred aspect, the present invention provides a process for the preparation of Obeticholic acid cyclohexane solvate which comprises the steps of:
a) adding Obeticholic acid to cyclohexane solvent, and
b) isolating the Obeticholic acid to cyclohexane solvate.

In still yet another preferred aspect, the present invention provides a process for the preparation of Obeticholic acid cyclohexane solvate which comprises the steps of:
a) dissolving Obeticholic acid in one or more of solvents,
b) treating the step a) solution with cyclohexane,
c) precipitating the Obeticholic acid to cyclohexane solvate.

In still yet another preferred aspect, the present invention provides a pharmaceutical composition comprising novel solvates of Obeticholic acid with one or more excipients.

In still yet another preferred aspect, the present invention provides a pharmaceutical composition comprising Obeticholic acid cyclohexane solvate with one or more excipients.

BRIEF DESCRIPTION OF DRAWINGS
Fig.1: Represents X-ray powder diffraction pattern of Obeticholic acid cyclohexane solvate.
Fig.2: Represents proton NMR of Obeticholic acid cyclohexane solvate.
Fig.3: Represents proton NMR of Obeticholic acid cyclohexane solvate after 13 days.
Fig.4: Represents proton NMR of Obeticholic acid cyclohexane solvate after 20 days at 90% RH.
Fig.5: Represents Overlay of X-ray Powder Diffraction Pattern of Obeticholic acid cyclohexane solvate at 90% RH.

DETAILED DESCRIPTION OF THE INVENTION
Accordingly, the present invention provides novel solvates of Obeticholic acid.

In a preferred embodiment, the present invention provides novel hydrocarbon solvate of Obeticholic acid.

In another preferred embodiment, the present invention provides cyclohexane solvate of Obeticholic acid.

In yet another preferred embodiment, the present invention provides cyclohexane solvate of Obeticholic acid which is characterized by X-ray diffraction pattern having peaks at about 4.2, 5.7, 15.5 and 16.2 ± 0.2 degrees 2?.

In yet another preferred embodiment, the present invention provides cyclohexane solvate of Obeticholic acid which is characterized by X-ray diffraction pattern having peaks at about 4.2, 5.7, 8.2, 8.4, 9.2, 9.6, 10.7, 12.0, 13.4, 13.5, 14.1, 15.5, 16.2, 17.1, 17.9, 18.3, 18.7, 19.1, 20.1 and 20.9 ± 0.2 degrees 2?.

In yet another preferred embodiment, the present invention provides cyclohexane solvate of Obeticholic acid which is characterized by X-ray diffraction pattern substantially as shown in Fig. 1.

In yet another preferred embodiment, the present invention provides cyclohexane solvate of Obeticholic acid which is further characterized by 1H-NMR spectrum as shown in Fig. 2.

In yet another preferred embodiment, the present invention provides cyclohexane solvate of Obeticholic acid which is further characterized by 1H-NMR spectrum as shown in Fig. 3.

In yet another preferred embodiment, the present invention provides cyclohexane solvate of Obeticholic acid which is further characterized by 1H-NMR spectrum as shown in Fig. 4.

In yet another preferred embodiment, the present invention provides stable cyclohexane solvate of Obeticholic acid, wherein the XRD pattern of cyclohexane solvate of Obeticholic acid after stability study is depicted in Fig. 5.

Cyclohexane solvate of Obeticholic acid is physically, thermally and chemically stable at 90 % RH. Cyclohexane solvate of Obeticholic acid appears to be crystalline and establishes very promising and exhibits good physical stability at normal packed conditions. The crystallinity Cyclohexane solvate reduced after drying at 60ºC and significant cyclohexane content is observed.

In yet another preferred embodiment, the present invention provides a process for the preparation of novel hydrocarbon solvates of Obeticholic acid, which comprises the steps of:
a) adding Obeticholic acid to a solvent or mixture of solvent, and
b) isolating the novel solvates of Obeticholic acid.

In yet another preferred embodiment, the present invention provides a process for the preparation of novel hydrocarbon solvates of Obeticholic acid, which comprises the steps of:
a) adding Obeticholic acid to a hydrocarbon solvent, and
b) isolating the novel solvates of Obeticholic acid.

In yet another preferred embodiment, the present invention provides a process for the preparation of novel hydrocarbon solvates of Obeticholic acid, which comprises the steps of:
a) adding Obeticholic acid to a solvent,
b) adding hydrocarbon solvent to the step a) solution, and
c) isolating the novel solvates of Obeticholic acid.

In yet another preferred embodiment, the present invention provides a process for the preparation of Obeticholic acid cyclohexane solvate, which comprises the steps of:
a) adding Obeticholic acid to cyclohexane solvent, and
b) isolating the Obeticholic acid to cyclohexane solvate.

In still yet another preferred embodiment, the present invention provides a process for the preparation of Obeticholic acid cyclohexane solvate, which comprises the steps of:
a) dissolving Obeticholic acid in one or more of solvents,
b) treating the step a) solution with cyclohexane,
c) precipitating the Obeticholic acid to cyclohexane solvate.

In still yet another preferred embodiment, the present invention provides a pharmaceutical composition comprising novel solvates of Obeticholic acid with one or more excipients.

In still yet another preferred embodiment, the present invention provides a pharmaceutical composition comprising Obeticholic acid cyclohexane solvate with one or more pharmaceutically acceptable excipients.

The term "stable" relates to a compound which after storage for up to 2 weeks, more suitably up to 4 weeks, still more suitably up to 12 weeks, or at least 12 weeks and especially up to 6 months, particularly at least 6 months at 25ºC. The solvates of the present invention are also stable at 40ºC / 75%RH for at least 6 months.

The present invention provides novel solvates of Obeticholic acid which are prepared by adding Obeticholic acid to a solvent and mixture of solvent, and applying any suitable technique to induce crystallization, to obtain the novel solvates of Obeticholic acid, wherein the solvent or mixture of solvents are selected from methanol, ethanol, n-propanol, isopropanol, n-butanol and t-butanol; benzene, toluene, xylene, heptane, hexane and cyclohexane; acetone, ethyl methyl ketone, diethyl ketone, methyl tert-butyl ketone, isopropyl ketone; methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate; acetonitrile, propionitrile, butyronitrile and isobutyronitrile; di-tert-butylether, dimethylether, diethylether, diisopropyl ether, 1,4-dioxane, methyltert-butylether, ethyl tert-butyl ether, tetrahydrofuran, 2-methyl tetrahydrofuran, 2-methoxyethanol and dimethoxyethane; formamide, DMF, DMAC, N-methyl-2-pyrrolidone, N-methylformamide, 2-pyrrolidone, 1-ethenyl-2-pyrrolidone; dichloromethane, 1,2-dichloroethane and chloroform; diethylenetriamine, ethylenediamine, morpholine, piperidine, pyridine, quinoline, tributylamine, diisopropyl amine.

The present invention provides novel solvates of Obeticholic acid which are prepared by adding Obeticholic acid to a solvent and mixture of solvent followed by adding an anti-solvent, wherein the anti-solvent is selected from methanol, ethanol, n-propanol, isopropanol, n-butanol and t-butanol; benzene, toluene, xylene, heptane, hexane and cyclohexane; acetone, ethyl methyl ketone, diethyl ketone, methyl tert-butyl ketone, isopropyl ketone; methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate; acetonitrile, propionitrile, butyronitrile and isobutyronitrile; di-tert-butylether, dimethylether, diethylether, diisopropyl ether, 1,4-dioxane, methyltert-butylether, ethyl tert-butyl ether, tetrahydrofuran, 2-methyl tetrahydrofuran, 2-methoxyethanol and dimethoxyethane; formamide, DMF, DMAC, N-methyl-2-pyrrolidone, N-methylformamide, 2-pyrrolidone, 1-ethenyl-2-pyrrolidone; dichloromethane, 1,2-dichloroethane and chloroform; diethylenetriamine, ethylenediamine, morpholine, piperidine, pyridine, quinoline, tributylamine, diisopropyl amine.

Solvates of the present invention can occur in different ratios of solvation. Solvent content of the crystal may vary in different ratios depending on the conditions applied. Solvate crystal forms of Obeticholic acid may comprise up to 5 molecules of solvent per molecule of Obeticholic acid, appearing in different solvated states including, amongst others, hemisolvate, monosolvate, disolvate, trisolvate crystals, intermediate solvates crystals, and mixtures thereof. Conveniently, the ratio of Obeticholic acid to the solvent may range between (5:1) and (1:5). In particular, the ratio may range from about 0.2 to about 3 molecules of solvent per 1 molecule of Obeticholic acid, more in particular, the ratio may range from about 1 to about 2 molecules of solvent per 1 molecule of Obeticholic acid, preferably the ratio is 1 molecule of solvent per 1 molecule of Obeticholic acid.

Processes for crystallization of novel solvates of Obeticholic acid embrace multiple combinations of techniques and variations thereof. As such, and by way of example, crystallization of novel solvates of Obeticholic acid may be executed by dissolving or dispersing Obeticholic acid at a suitable temperature in the solvent whereby portion of the said solvent evaporates increasing the concentration of the Obeticholic acid in the said solution or dispersion, cooling the said mixture, and optionally washing and/or filtering and drying resulting novel solvates of Obeticholic acid. Optionally, novel solvates of Obeticholic acid may be prepared by dissolving or dispersing Obeticholic acid in a solvent medium, cooling said solution or dispersion and subsequently filtering and drying the obtained novel solvates. Another example of preparation of solvates of Obeticholic acid could be by saturating Obeticholic acid in the solvent medium, and optionally filtering, washing and drying obtained crystals.

Crystal formation may as well involve more than one crystallization process. In certain cases, one, two or more extra crystallization steps may be advantageously performed for different reasons, such as, to increase the quality of the resulting solvate. For instance, novel solvates of Obeticholic acid of the present invention could also be prepared by adding a solvent to Obeticholic acid, stirring the solution at a fixed temperature until the substances would be fully solved, concentrating the solution by vacuum distillation, and cooling. A first crystallization would take place and the formed crystals would be newly washed with a solvent, and followed by dissolution of Obeticholic acid with the solvent to form the desired solvates. Recrystallization of the reaction mixture would occur, followed by a cooling step from reflux. The formed solvates would optionally be filtered and allowed to dry.

Each step for producing the novel crystal and solvate of the present invention may be carried out under atmospheric pressure, under reduced pressure, or under pressurization.

The pharmaceutical compositions of the present invention as a dosage form, e.g., solid, liquid, powder, elixir, aerosol, syrups, injectable solution, etc. Dosage forms may be adapted for administration to the patient by oral, buccal, parenteral, ophthalmic, rectal and transdermal routes or any other acceptable route of administration. Oral dosage forms include, but are not limited to, tablets, pills, capsules, syrup, troches, sachets, suspensions, powders, lozenges, elixirs and the like. Tablets and powders may also be coated with an enteric coating. The enteric-coated powder forms may have coatings containing at least phthalic acid cellulose acetate, hydroxypropylmethyl cellulose phthalate, polyvinyl alcohol phthalate, carboxy methyl ethyl cellulose, a copolymer of styrene and maleic acid, a copolymer of methacrylic acid and methyl methacrylate, and like materials, and if desired, the coating agents may be employed with suitable plasticizers and/or extending agents. A coated capsule or tablet may have a coating on the surface thereof or may be a capsule or tablet comprising a powder or granules with an enteric-coating.

In yet another embodiment, the pharmaceutically acceptable excipient is selected from the group consisting of polyvinylpyrrolidone (also called povidone or PVP), polyvinyl alcohol, hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), methyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, hydroxyethylcellulose, hypromellose phthalate (HPMCP), lactose monohydrate, polyvinyl acetate, maltodextrins, cyclodextrins, gelatins, sugars, water soluble and water insoluble polymers and combinations comprising one or more of the foregoing hydrophilic carriers.

While the present invention has been described in terms of its specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention. The invention is illustrated below with reference to inventive and comparative examples and should not be construed to limit the scope of the invention.

EXAMPLES
Example 1: Process for the preparation of Obeticholic acid cyclohexane solvate:

Obeticholic acid (500 mg) was dissolved in THF (1.7 ml) at room temperature. The obtained clear solution, afterwards cyclohexane (40ml) was added to the solution and stirring. The precipitation occurred after one hour and the slurry continued for 48 hrs. The solid filtered and dried to obtain Obeticholic acid cyclohexane solvate.

Example 2: Process for the preparation of Obeticholic acid cyclohexane solvate:

Obeticholic acid (600 mg) was dissolved in THF (2 ml) at room temperature. The obtained clear solution, afterwards cyclohexane (40ml) was added to the solution and stirring. The precipitation occurred after one hour and the slurry continued for 24 hrs. The solid filtered and dried to obtain Obeticholic acid cyclohexane solvate.

Example 2: Process for the preparation of Obeticholic acid cyclohexane solvate:
Obeticholic acid (600 mg) was suspended in 1:40 mixture of 1,4 dioxane and 49.2 ml of cyclohexane at room temperature and stirred for 2 hours. The obtained solid filtered and suck dried for 30 min. The slightly wet material dried further at hot air oven at 30 0C for 20 hours.

Example 3: Process for the preparation of Obeticholic acid cyclohexane solvate:
Obeticholic acid (2 grams) was suspended in 1:40 mixture of 1,4-dioxane and cyclohexane (164 ml) at room temperature and stirred for 2 hours. The obtained solids filtered and suck dried for 30 mins. The slightly wet material dried further at hot air oven at 40 0C for 20 hours.

Example 4: Process for the preparation of Obeticholic acid cyclohexane solvate:
Obeticholic acid (3 grams) was suspended in 1:40 mixture of 1,4-dioxane and cyclohexane (246 ml) at room temperature and stirred for 2 hours. The obtained solids filtered and suck dried for 30 mins. The slightly wet material dried further at hot air oven at 30 0C for 14 hours.

,CLAIMS:We claim:
1. Novel solvates of Obeticholic acid.
2. Novel solvates of Obeticholic acid as claimed in claim 1, wherein the solvate is hydrocarbon solvates.

3. Novel solvates of Obeticholic acid as claimed in claim 2, preferably cyclohexane solvate.

4. Cyclohexane solvate of Obeticholic acid according to claim 3, characterized by:
a) X-ray diffraction pattern having peaks at about 4.2, 5.7, 15.5 and 16.2 ± 0.2 degrees 2?,
b) X-ray diffraction pattern substantially as shown in Fig. 1, and
c) 1H-NMR spectrum as shown in Figs. 2, 3 and 4.

5. A process for the preparation of novel solvates of Obeticholic acid, which comprises the steps of:
a) adding Obeticholic acid to a solvent or a mixture of solvent, and
b) isolating the novel solvates of Obeticholic acid.

6. A process for the preparation of novel hydrocarbon solvates of Obeticholic acid, which comprises the steps of:
a) adding Obeticholic acid to a hydrocarbon solvent, and
b) isolating the novel solvates of Obeticholic acid.

7. A process for the preparation of novel hydrocarbon solvates of Obeticholic acid, which comprises the steps of:
a) adding Obeticholic acid to a solvent,
b) adding hydrocarbon solvent to the step a) solution, and
c) isolating the novel solvates of Obeticholic acid.

8. A process for the preparation of Obeticholic acid cyclohexane solvate which comprises the steps of:
a) adding Obeticholic acid to cyclohexane solvent, and
b) isolating the Obeticholic acid to cyclohexane solvate.

9. A process for the preparation of Obeticholic acid cyclohexane solvate which comprises the steps of:
a) dissolving Obeticholic acid in one or more of solvents,
b) treating the step a) solution with cyclohexane,
c) precipitating the Obeticholic acid to cyclohexane solvate.

10. The process clamed in the claim 5 - 9, wherein the solvent or mixture of solvents are selected from methanol, ethanol, n-propanol, isopropanol, n-butanol and t-butanol; benzene, toluene, xylene, heptane, hexane and cyclohexane; acetone, ethyl methyl ketone, diethyl ketone, methyl tert-butyl ketone, isopropyl ketone; methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate; acetonitrile, propionitrile, butyronitrile and isobutyronitrile; di-tert-butylether, dimethylether, diethylether, diisopropyl ether, 1,4-dioxane, methyltert-butylether, ethyl tert-butyl ether, tetrahydrofuran, 2-methyl tetrahydrofuran, 2-methoxyethanol and dimethoxyethane; formamide, DMF, DMAC, N-methyl-2-pyrrolidone, N-methylformamide, 2-pyrrolidone, 1-ethenyl-2-pyrrolidone; dichloromethane, 1,2-dichloroethane and chloroform; diethylenetriamine, ethylenediamine, morpholine, piperidine, pyridine, quinoline, tributylamine, diisopropyl amine.

Dated this Sixteenth (16th) day of September 2017.

__________________________________
Dr. S. Padmaja
Agent for the Applicant
IN/PA/883