DESC:CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to the filing dates of Indian Provisional Application No. 201941008140, filed on March 01, 2019;

FIELD OF THE INVENTION:
The present invention relates to Co-crystal of Roxadustat with proline and its preparation thereof.

BACKGROUND OF THE INVENTION:
Roxadustat is chemically known as [(4-hydroxy-1-methy1-7-phenoxy-isoquinoline-3-carbony1)-amino]-acetic acid and is represented by Formula 1. Roxadustat is for the treatment of anemia in patients with chronic kidney disease (CKD). It is in Phase III clinical development in US.

Formula I

Roxadustat was first disclosed in US patent 7323475B2

US patent 8883823 disclosed crystalline Form A, Form B, Form C & Form D [DMSO: water solvate], crystalline sodium salt, crystalline L-arginine salt, crystalline L-lysine salt, crystalline ethanolamine salt, crystalline diethanolamine salt, crystalline tromethamine salt and their preparations thereof.

US patent 9206134B2 disclosed crystalline forms I, II, III, IV, V, VI & VII of Roxadustat and their preparations thereof.

IN201641016266 patent application disclosed amorphous solid dispersion comprising Roxadustat and a pharmaceutically acceptable carrier and its preparation process.

IN201741007950 patent application disclosed Co-crystal of Roxadustat comprising Roxadustat and Co-crystal former selected from caffeine, adenine, thymine, saccharine or the like.

IN201741028591 patent application disclosed Form- ?, Form-d, Co-crystal of Roxadustat with L-proline, Co-crystal of Roxadustat with Nicotinamide, CCo-crystal of Roxadustat with Urea.

The inventors of the present invention have developed proline Co-crystal of Roxadustat having improved stability thus suitable for formulation development and is commercially viable and economical.

OBJECT AND SUMMARY OF THE INVENTION:
The main object of the present invention provides Co-crystal of Roxadustat with D-proline and its preparation thereof.

In one aspect, the Co-crystal of Roxadustat D-proline is characterized by powder X-ray diffraction pattern having peaks at 3.55, 7.13, 9.52, 10.16, 10.72, 11.86, 14.29, 17.16, 17.94, 19.15,19.45, 20.02, 20.40, 20.64, 21.30, 21.90, 22.75, 23.88, 24.16, 25.23, 26.14, 26.98, 27.21, 28.94, 29.57, 30.02, 30.87, 32.59, 35.42, 38.64, 43.1,45.1,46.5 ± 0.2° degrees 2?.

Yet in another aspect, the Co-crystal of Roxadustat D-proline may be characterized by powder X-ray diffraction pattern shown in Figure 1.

Yet in another aspect, the present invention provides a process for the preparation of Co-crystal of Roxadustat D-proline by contacting Roxadustat with D-proline in the presence of a solvent followed by isolating the Co-crystal of Roxadustat D-proline.

Yet in another aspect, the Co-crystal formed according to the present invention comprises Roxadustat and D-proline in the molar ratio of 1:1.

Brief description of the figures:

Figure 1 depicts an X-Ray Powder Diffraction (XRPD) pattern of a Roxadustat D-proline (1:1) Co-crystal.
Figure 2 depicts a differential scanning calorimetry (DSC) pattern of a Roxadustat D-proline (1:1) Co-crystal.
Figure 3 depicts thermogravimetric analysis (TGA) pattern of a Roxadustat D-proline (1:1) Co-crystal.

DETAIL DESCRIPTION OF THE INVENTION:

The present invention relates to Co-crystal of Roxadustat and its preparation thereof.

According to the present invention, the conformer or Co-crystal is D-proline.

In one embodiment, the present invention relates to Co-crystal of Roxadustat D-proline characterized by powder X-ray diffraction pattern having peaks at X-ray diffraction pattern having peaks at 3.55, 7.13, 9.52, 10.16, 10.72, 11.86, 14.29, 17.16, 17.94, 19.15,19.45, 20.02, 20.40, 20.64, 21.30, 21.90, 22.75, 23.88, 24.16, 25.23, 26.14, 26.98, 27.21, 28.94, 29.57, 30.02, 30.87, 32.59, 35.42, 38.64, 43.1, 45.1, 46.5 ± 0.2° degrees 2?.

Yet in another embodiment, the Co-crystal of Roxadustat D-proline may be characterized by powder X-ray diffraction pattern shown in Figure 1.

Yet in another embodiment, the present invention relates to process for the preparation of Co-crystal of Roxadustat comprising the steps of
a) contacting Roxadustat with D-proline in presence of an organic solvent,
b) heating the reaction mass,
c) isolating Co-crystal of Roxadustat D-proline.

According to the present invention, Roxadustat and D-proline may be contacted in an organic solvent selected from acetone, ethyl acetate, isopropyl acetate, Isopropyl alcohol or mixtures thereof.

According to the present invention, Roxadustat and D-proline may be slurred in acetone, Ethyl acetate or isopropyl acetate at room temperature and heated to about 50-75oC followed by cooling to room temperature and maintained. The resultant reaction mass may be filtered to get Co-crystal of Roxadustat D-proline.

According to the present invention, Roxadustat may be heated at about 50°C to 75°C. In particular useful embodiments of the present invention Roxadustat may be heated at about 60°C-65°C.

According to the present invention, the Co-crystal of Roxadustat D-proline may be isolated by employing one or more techniques selected from the group consisting of filtration, decantation, extraction, distillation, evaporation, precipitation, concentration, crystallization, centrifugation, and recrystallization. The Roxadustat D-proline (1:1) Co-crystal may further be dried using conventional techniques.

According to the present invention, the Co-crystal of Roxadustat D-proline formed by the present process is in the molar ratio of 1:1.

Yet in another embodiment, the Co-crystal of Roxadustat D-proline is characterized by differential scanning calorimetric (DSC) thermogram having endothermic peaks at about 206.84°C.

The pharmaceutical composition of the present invention may be formulated in accordance with conventional methods and may be prepared in the form of oral formulations such as tablets, pills, powders, capsules, syrups, emulsions, micro emulsions, and others, or formulation for parenteral injection, e.g., intramuscular, intravenous, or subcutaneous administration. The pharmaceutical composition of the present invention may comprise the solid dispersion, and any possible carrier and excipient. The pharmaceutical composition of the present invention comprises of Co-crystal of Roxadustat D-Proline and at least one pharmaceutically acceptable excipient.

Indicative stability:
In yet another embodiment, the physical stability of 1:1 Co-crystal of Roxadustat D-Proline was determined by storing the samples at 40°C and 75% relative humidity (RH) and at 25°C and 60% relative humidity (RH) conditions for six months and the samples were analyzed by PXRD. The results are shown in below Table 1. The 1:1 Co-crystal of Roxadustat D-Proline was found to be physically stable at 40°C and 75% relative humidity (RH) and at 25°C and 60% relative humidity (RH) conditions up to six months.
Table 1
Conditions/ Polymorph 1:1 Co-crystal of
Roxadustat D-Proline
PXRD
at 40°C/75% RH
Initial Co-crystal
1 month Stable
2 months Stable
3 months Stable
6 months Stable
at 25°C/60% RH
Initial Co-crystal
1 month Stable
2 months Stable
3 months Stable
6 months Stable

Solubility
The aqueous solubility of 1:1 Co-crystal of Roxadustat D-proline and Roxadustat Form A were determined in water at 37°C. The results are shown in the following Table 2. The Roxadustat D-Proline Co-crystal shows nearly 13 folds increase in aqueous solubility in comparison with Roxadustat Form A.
Table 2:
Solvent Media Solubility at 37°C (mg/mL)
Roxadustat
(Form A) 1:1 Co-crystal of Roxadustat D-proline
Water 0.003 0.04

Photostability
The photostability of Co-crystal of Roxadustat with D-Proline and Roxadustat Form A were tested by exposing the samples to UV/VIS radiation for a period of 24h and analyzed by HPLC. The results are shown in Table 3. The results shows that 1:1 Co-crystal of Roxadustat D-Proline was found to be photochemically stable for 24h when exposed to UV/VIS radiation whereas Roxadustat Form A shows the formation of photoisomer (m/z 352) up to a level of 0.14%.

Photoisomer

Table 3
Composition Content of photo isomer by HPLC (%)
Initial 24h
Roxadustat Form A 0.08 0.14
Co-crystal of Roxadustat D-Proline (1:1) 0.02 0.01

Another advantage of this innovation is to prepare purer form of Roxadustat by forming Co-crystal with D-proline with absence of impurities particularly the photoisomer. The purification process involves, mixing of Roxadustat in an organic solvent with D-Proline and isolating the crystalline product in the form of a Co-crystal. The purity of the Co-crystal is higher than the Roxadustat Form A. The results are shown in the following Table 4.
Table 4
API/Co-crystal Purity by HPLC (%)
Roxadustat Form A (Input) 99.86
Co-crystal of Roxadustat D-Proline (1:1) 99.94

PXRD Analysis
The said Co-crystal of the present invention is characterized by their X-Ray powder diffraction pattern. The PXRD measurements were carried out using PANalytical, X'Pert PRO powder diffractometer equipped with goniometer of ?/? configuration and X'Celerator detector. The Cu- anode X-ray tube is operated at 40kV and 30mA. The experiments were conducted over the 2? range of 2.0º-50.0°, 0.030° step size and 50 seconds step time.
Differential Scanning Calorimetry (DSC)
The DSC measurements were carried out on TA Q2000 of TA instruments. The experiments were conducted from 30°C to 250°C at a heating rate of 10.0°C/min and nitrogen purging at a flow rate of 50ml/min. Standard aluminum pans covered by lids with pin hole were used.
Thermogravimetric Analysis (TGA)
TGA/DTA was recorded using the instrument TA Q5000 of TA instruments. The experiments were performed at a heating rate of 10.0 °C/min over a temperature range of 30°C-300°C purging with nitrogen at a flow rate of 25ml/min.

Purity by HPLC
Waters HPLC system having 2690 model pump and UV detector with Empower chromatography software or its equivalent was for determination of purity of Roxadustat D-Proline co-crystal. Ascentis Express pheny-Hexyl, 100*3mm, 2.7 ?m column was used with the mobile phase of 10 mM phosphate buffer solution – 2.5 and Acetonitrile at the detection wavelength of 220 nm and flow rate of 1.0 mL/min.
The following examples are provided for illustrative purposes only and are not intended to limit the scope of the invention in anyway.

EXAMPLES:

Process for the preparation of 1:1 cocrystal of Roxadustat D-Proline

Example 1:
In a RBF, charged Roxadustat (1.0 g), D-Proline (0.32g) and Acetone (20mL) at 25±5°C. Heated the contents to 60-65°C and stirred for 30-40min at 60-65°C. The reaction mass was slowly cooled to 25±5°C and maintained under stirring at 25±5°C for 16h. The product obtained was filtered, washed with Acetone (2mL) and dried the material under vacuum at 40°C for 16h. The solid obtained was identified as 1:1 Co-crystal of Roxadustat D-Proline.
Yield: 1.07g

Example 2:
In a RBF, charged Roxadustat (0.5 g), D-Proline (0.16g) and Ethyl acetate (25mL) at 25±5°C. Heated the contents to 60-65°C and stirred for 30-40min at 60-65°C. The reaction mass was slowly cooled to 25±5°C and maintained under stirring at 25±5°C for 16h. The product obtained was filtered, washed with Ethyl acetate (2mL) and dried the material under vacuum at 40°C for 16h. The solid obtained was identified as 1:1 Co-crystal of Roxadustat D-Proline.

Example 3:
In a RBF, charged Roxadustat (0.5 g), D-Proline (0.16g) and Isopropyl acetate (20mL) at 25±5°C. Heated the contents to 60-65°C and stirred for 30-40min at 60-65°C. The reaction mass was slowly cooled to 25±5°C and maintained under stirring at 25±5°C for 16h. The product obtained was filtered, washed with Isopropyl acetate (2mL) and dried the material under vacuum at 40°C for 16h. The solid obtained was identified as 1:1 Co-crystal of Roxadustat D-Proline.

Example 4:
In a RBF, charged Roxadustat (0.5 g), D-Proline (0.16g) and Isopropyl alcohol (20mL) at 25±5°C. Heated the contents to 60-65°C and stirred for 30-40min at 60-65°C. The reaction mass was slowly cooled to 25±5°C and maintained under stirring at 25±5°C for 16h. The product obtained was filtered, washed with Isopropyl alcohol (2mL) and dried the material under vacuum at 40°C for 16h. The solid obtained was identified as 1:1 Co-crystal of Roxadustat D-Proline.
,CLAIMS:1) A Co-crystal of Roxadustat with D-proline
2) The Co-crystal as claimed in claim 1, wherein the molar ratio of Roxadustat and D-proline is 1:1.
3) The Co-crystal as claimed in claim 1, is characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of 9.52, 10.16, 10.72, 14.29, 17.16, 19.15, 20.40, 22.75 and 25.23 ± 0.2° 2?.
4) The Co-crystal as claimed in claim 3, is substantially shown in Figure-1.
5) The Co-crystal as claimed in claim 1, is prepared comprising the steps of
a) contacting Roxadustat with D-proline in presence of an organic solvent,
b) heating the reaction mass,
c) isolating Co-crystal of Roxadustat D-proline.
6) The process as claimed in claim 5, wherein the organic solvent is selected from acetone, ethyl acetate, isopropyl acetate, isopropyl alcohol and mixtures thereof.
7) The Co-crystal of Roxadustat D-proline as claimed in claim 1 is free of photoisomer.
8) The Co-crystal of Roxadustat D-proline as claimed in any of the preceding claims, have purity of 99.94% by HPLC.
9) The Co-crystal of Roxadustat D-proline as claimed in claim 1 is characterized by differential scanning calorimetric (DSC) thermogram having endothermic peaks at about 206.84°C.
10) A pharmaceutical composition comprising the Co-crystal as defined in any one of claims 1 to 7 and at least one pharmaceutically acceptable excipient.