The present invention relates to solid forms of methyl-4-[[2-fluoro-3-[(6-methylpyridin-3-yl)carbamoyl amino] phenyl] methyl] piperazine-1-carboxylate of Formula I or pharmaceutically acceptable salts, solvates or hydrates thereof, methods for preparation and pharmaceutical compositions thereof.

The present invention also relates to pharmaceutically acceptable salts of Omecamtiv Mecarbil of Formula I & process for preparation thereof.
The present invention further relates to a composition comprising solid forms of Omecamtiv Mecarbil of Formula I along with at least one pharmaceutical acceptable excipients thereof.
BACKGROUND OF THE INVENTION
Omecamtiv Mecarbil (CK-1827452) of Formula I having chemical name Methyl-4-[[2-fluoro-3-[(6-methylpyridin-3-yl)carbamoylamino] phenyl] methyl] piperazine-1-carboxylate and represented with structure as follows:

Omecamtiv Mecarbil is a cardiac-specific myosin activator. Omecamtiv Mecarbil is being studied for the treatment of chronic heart failure with reduced ejection fraction (GALACTIC-HF).

U.S. Patent No. 9,988,354 discloses dihydrochloride monohydrate salt of Omecamtiv Mecarbil.
WO 2020/037164 discloses free base crystalline forms i.e. Form III, Form IV, Form V, Form VI, Form VI, amorphous hydrochloride salt and different crystalline acid salts of Omecamtiv Mecarbil.
Although there are certain known polymorphic forms of Omecamtiv Mecarbil in the prior publications, however the development of new solid forms of a pharmaceutically useful compound provides a new opportunity to improve the performance characteristics of a pharmaceutical product. It enlarges the range of materials that a formulation scientist can use for designing pharmaceutical formulation having desired characteristics.
The solid forms of the present invention have advantages in the preparation of pharmaceutical compositions of the Omecamtiv Mecarbil, such as ease of processing, handling, and dosing. In particular, they exhibit improved physicochemical properties, such as solubility, stability to stress, and rate of dissolution, rendering them particularly suitable for the manufacture of various pharmaceutical dosage forms.
Based on aforesaid, the present invention is focussed towards the development of new crystalline forms of Omecamtiv Mecarbil by employing simple, low cost and less time consuming processes.
OBJECT OF THE INVENTION
The main object of the present invention is to provide solid forms of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts, solvates or hydrates thereof, which possesses good stability, good processability and other favourable properties.
Another object of the present invention is to provide pharmaceutically acceptable salts of Omecamtiv Mecarbil of Formula I & process for preparation thereof.

Another object of the present invention is to provide novel crystalline form of Omecamtiv Mecarbil of Formula I designated as MK-1 and its process for preparation.
Another object of the present invention is to provide novel solvates of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts thereof.
Another object of the present invention is to provide a stable amorphous form of Omecamtiv Mecarbil of Formula I or pharmaceutical acceptable salt thereof.
Yet another object of the present invention is to provide a composition comprising solid form of Omecamtiv Mecarbil or pharmaceutically acceptable salts, along with at least one pharmaceutical acceptable excipients.
SUMMARY OF THE INVENTION
In the main aspect, the present invention is to provide solid forms of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts.
In one aspect, the present invention provides a crystalline Form MK-1 of Omecamtiv Mecarbil of Formula I, characterized by XRPD having peaks selected from (29 values) at 6.38, 13.02, 18.76 and 21.09 ±O.2°0.
In another aspect, the present invention provides a crystalline Form MK-1 of Omecamtiv Mecarbil of Formula I, characterized by XRPD having peaks at 4.67, 5.59, 6.38, 7.31, 7.66, 9.37, 10.53, 11.24, 13.02, 14.04, 15.03, 15.26, 15.67, 16.96, 17.43, 17.71, 18.51, 18.76, 19.34, 20.30, 20.52, 21.09, 21.76, 22.09, 23.30, 23.56, 24.24, 24.86, 25.35, 26.60, 27.26, 27.51, 28.49, 29.21, 29.98, 30.36, 31.06, 32.88, 33.75, 36.80 and 39.32 ±O.2°0.
In one aspect, the present invention provides a crystalline Form MK-1 of Omecamtiv Mecarbil of Formula I, characterized by FT-IR pattern having peaks at 3291.47, 3096.7, 2950.37, 2867.87, 2819.91, 2776.73, 1719.22, 1697.28, 1659.46, 1640.61 and 1625.39 cm"1.

In another aspect, the present invention is to provide novel N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts and process of preparation thereof.
In another aspect, the present invention provides a crystalline N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I, characterized by XRPD having at least two peaks selected from (20 values) at 3.04, 6.14, 7.25, 9.26, 10.52, 11.56, 12.37, 13.05, 13.68, 14.79, 15.22, 15.65, 16.21, 16.75, 17.09, 17.41, 17.60, 18.16, 18.90, 19.38, 19.92, 20.29, 20.64, 21.09, 22.02, 22.88, 23.16, 23.97, 24.61, 25.35, 26.17, 26.97, 27.54, 28.03, 28.94, 30.45, 31.48, 32.53, 33.49, 35.72, 36.05, 37.79 and 38.58±0.2.
In another aspect, the present invention provides a crystalline N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I, characterized by FT-IR pattern having peaks at 3326.7, 3293.76, 3173.96, 3070.19, 2986.06, 2950.15, 2870.68, 2819.81, 2775.77, 1709.26, 1696.7, 1651.11, 1626.58 and 1608.68 cm-1.
In another aspect, the present invention provides a process for preparation of solid form of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts thereof, wherein said process comprising the steps of:
a) adding Omecamtiv Mecarbil or pharmaceutically acceptable salts thereof in a solvent;
b) optionally adding anti-solvent to the solution obtained in step a); and
c) isolating the solid form of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts thereof.
In another aspect, the present invention provides a process for preparation of crystalline Form MK-1 of Omecamtiv Mecarbil of Formula I, wherein said process comprising the steps of:
a) adding Omecamtiv Mecarbil in solvent(s);
b) heating the reaction mixture at suitable temperature;
c) optionally adding anti-solvent to the solution obtained in step b);

d) cooling the reaction mixture at suitable temperature; and
e) isolating the crystalline Form MK-1 of Omecamtiv Mecarbil.
In another aspect, the present invention provides a process for preparation of crystalline N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I, wherein said process comprising the steps of:
a) adding Omecamtiv Mecarbil in N-methylpyrrolidone;
b) adding anti-solvent to the solution obtained in step a); and
c) isolating the N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I.
In another aspect, the present invention provides pharmaceutical acceptable salt of Omecamtiv Mecarbil of Formula I.
In another aspect, the present invention provides a stable amorphous form of Omecamtiv Mecarbil of Formula I or pharmaceutical acceptable salt thereof.
In another embodiment, the present invention provides a stable amorphous form of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salt thereof, wherein said Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salt is stable at 40°C/75% RH for equal to or atleast six months or 25°C/60% RH, for a period of equal to or at least 12 months and contains less than about 0.5% (wt/wt) of total impurities.
In another aspect, the present invention provides a stable amorphous form of organic acid addition salt of Omecamtiv Mecarbil of Formula I.
In another aspect, the present invention provides a process for the preparation of stable amorphous form of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salt thereof, comprising the steps:
a) dissolving Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salt thereof in suitable solvent,
b) stirring the reaction mixture to get the clear solution, and

c) isolating the amorphous form of Omecamtiv Mecarbil of Formula I or pharmaceutical acceptable salt thereof.
DETAILED DESCRIPTION OF THE INVENTION
Detail Description of the Drawings:
Fig. 1, which represents the X-ray (powder) diffraction (XRPD) pattern of the crystalline
FormMK-1 of Omecamtiv Mecarbil.
Fig. 2, which represents the Differential Scanning calorimetry (DSC) of the crystalline
FormMK-1 of Omecamtiv Mecarbil.
Fig. 3, which represents the Thermogravimetric analysis (TGA) of the crystalline Form
MK-1 of Omecamtiv Mecarbil.
Fig. 4, which represents the Fourier-transform infrared spectroscopy (FT-IR) of the
crystalline Form MK-1 of Omecamtiv Mecarbil.
Fig. 5, which represents the X-ray (powder) diffraction (XRPD) pattern of the crystalline
Form of N-methylpyrrolidone solvate of Omecamtiv Mecarbil.
Fig. 6, which represents the Differential Scanning calorimetry (DSC) of the crystalline
Form of N-methylpyrrolidone solvate of Omecamtiv Mecarbil.
Fig. 7, which represents the Thermogravimetric analysis (TGA) of the crystalline Form
of N-methylpyrrolidone solvate of Omecamtiv Mecarbil.
Fig. 8, which represents the Fourier-transform infrared spectroscopy (FT-IR) of the
crystalline Form of N-methylpyrrolidone solvate of Omecamtiv Mecarbil.
The names used herein to characterize a specific form, e.g. "Form MK-1", should not be considered limiting with respect to any other substance possessing similar or identical physical and/or chemical characteristics, but rather it should be understood that these designations are mere identifiers.
"Pharmaceutically acceptable salts" or "salts" as used in the context of the present invention includes organic or inorganic acid addition salts, but are not limited to pamoate salt, 2,3-dibenzoyl-tartarate, hydrochloride salt, hydrobromide salt, sulphate, phosphate salt; formate salt, acetate salt, diphenyl acetate salt, triphenylacetate salt, caprylate salt,

dichloroacetate salt, trifluoro acetate salt, propionate salt, butyrate salt, lactate salt, citrate, gluconate salt, mandelate salt, tartarate salt, malate salt, adipate salt, aspartate salt, fumarate salt, glutamate salt, maleate salt, malonate salt, succinate salt, oxalate salt, benzoate salt, ^-chlorobenzoate salt, nicotinate salt, Salicylate salt, 1-hydroxy-naphthalene-2-carboxylate salt, hydroxynaphthalene-2-carboxylate salt, ethanesulfonate salt, ethane-l,2-disulfonate salt, 2-hydroxyethane sulfonate salt, methanesulfonate salt, (+)-camphor-10-sulfonate salt, benzenesulfonate salt, naphthalene-2-sulfonate salt, p-toluenesulfonate salt; pharmaceutically acceptable bases such as metal salts including alkali metal or alkaline earth metal salts for example sodium, potassium, magnesium, calcium, barium or zinc salts, ammonium salts; and the like.
As used herein, "solvate" means a physical association of a compound with one or more solvent molecules, whether organic or inorganic. The solvate may comprise either a stoichiometric or nonstoichiometric amount of the solvent molecules.
The crystalline forms may be prepared by a variety of methods, including methods other than the methods disclosed in the present invention, for example, crystallization or recrystallization from a suitable solvent, sublimation, growth from a melt, solid state transformation from another phase, crystallization from a supercritical fluid, and jet spraying. Techniques for crystallization or recrystallization of crystalline forms from a solvent mixture include, for example, evaporation of the solvent, decreasing the temperature of the solvent mixture, crystal seeding a supersaturated solvent mixture of the molecule and/or salt, freeze drying the solvent mixture, and addition of anti-solvents (counter solvents) to the solvent mixture.
"Solvent" as used in the context of the present invention refers to polar or non-polar solvents selected from, but not limited to, the group comprising of alcohols, hydrocarbons, halogenated solvents, esters, ethers, ketones, sulfoxides, formamide, amides, nitriles, pyrrolidines, carbonates, water and the like. Specifically, the suitable solvent as used in the present invention is selected from, but not limited to, tetrahydrofuran, toluene, o/m/p-xylene, 1,4-dioxane, dichlorom ethane, carbon tetrachloride, dichloroethane, dichlorobenzene, chlorobenzene, methanol, ethanol,

isopropyl alcohol, butanol, t-butanol, acetonitrile, ethyl acetate, acetone, methyl ethyl ketone, 2-methyl tetrahydrofuran, butyl acetate, isobutyl acetate, t-butyl acetate, propyl acetate, propylene acetate, methyl t-butyl ketone, dimethyl sulfoxide, N-methyl pyrrolidine, dimethyl acetamide, dimethyl formamide, N-methyl acetamide, acetamide, methyl isobutyl ketone, propionitrile, methyl ethyl ether, methyl tert-butyl ether, dimethyl ether, diisopropyl ether, diethyl ether, cyclohexane, hexane, n-heptane, water and mixture thereof.
"Anti-solvent" as used herein refers to, but are not limited to: saturated or unsaturated, linear or branched, cyclic or acyclic, Ci to Cio hydrocarbons, such as heptanes, cyclohexane, or methylcyclohexane; ethers, such as ethoxyethane (diethyl ether), di-isopropyl ether (DIPE), methoxyethane (methyl ethyl ether), 2-methoxy-2-methylpropane (MTBE), and phenoxybenzene (diphenyl ether) water; or any mixtures thereof.
"Solid forms" as used herein refers to polymorphs, crystalline or amorphous, solvates, hydrates and co-crystals, premix, solid dispersion, solid solution, or mixture thereof in any proportion.
In another embodiment, the present invention provides a solid forms of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salt thereof,
In another embodiment, the present invention provides substantially pure solid forms of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts thereof.
In another embodiment, the present invention provides a crystalline Form MK-1 of Omecamtiv Mecarbil of Formula 1, characterized by X-ray (powder) diffraction (XRPD) having at least two peaks selected from (20 values) 4.67, 5.59, 6.38, 7.31, 7.66, 9.37, 10.53, 11.24, 13.02, 14.04, 15.03, 15.26, 15.67, 16.96, 17.43, 17.71, 18.51, 18.76, 19.34, 20.30, 20.52, 21.09, 21.76, 22.09, 23.30, 23.56, 24.24, 24.86, 25.35, 26.60, 27.26, 27.51, 28.49, 29.21, 29.98, 30.36, 31.06, 32.88, 33.75, 36.80 and 39.32 ±0.2.

In other embodiment, the present invention provides a crystalline Form MK-1 of Omecamtiv Mecarbil of Formula 1, characterized by X-ray (powder) diffraction (XRPD) pattern as depicted in Fig-1.
In other embodiment, the present invention provides a crystalline Form MK-1 of Omecamtiv Mecarbil of Formula 1, characterized by Differential Scanning calorimetry (DSC) as depicted in Fig-2.
In other embodiment, the present invention provides a crystalline Form MK-1 of Omecamtiv Mecarbil of Formula 1, characterized by Thermogravimetric analysis (TGA) as depicted in Fig-3.
In other embodiment, the present invention provides a crystalline Form MK-1 of Omecamtiv Mecarbil of Formula 1, characterized by Fourier-transform infrared spectroscopy (FT-IR) pattern as depicted in Fig-4.
In other embodiment, the present invention provides a crystalline Form MK-1 of Omecamtiv Mecarbil of Formula I, characterized by FT-IR pattern having peaks at 3291, 3096.7, 2950.37, 2867.87, 2819.91, 2776.73, 1719.22, 1697.28, 1659.46, 1640.61 and 1625.39 cm-1.
In other embodiment, the present invention provides crystalline N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I, characterized by X-ray (powder) diffraction (XRPD) having at least two peaks selected from (29 values) at 3.04, 6.14, 7.25, 9.26, 10.52, 11.56, 12.37, 13.05, 13.68, 14.79, 15.22, 15.65, 16.21, 16.75, 17.09, 17.41, 17.60, 18.16, 18.90, 19.38, 19.92,20.29,20.64,21.09,22.02,22.88,23.16,23.97, 24.61, 25.35, 26.17, 26.97, 27.54, 28.03, 28.94, 30.45, 31.48, 32.53, 33.49, 35.72, 36.05, 37.79 and 38.58±0.2.
In other embodiment, the present invention provides a crystalline N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I, characterized by X-ray (powder) diffraction (XRPD) pattern as depicted in Fig-5.

In other embodiment, the present invention provides a crystalline N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I, characterized by Differential Scanning calorimetry (DSC) as depicted in Fig-6.
In other embodiment, the present invention provides a crystalline N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I, characterized by Thermogravimetric analysis (TGA) as depicted in Fig-7.
In other embodiment, the present invention provides a crystalline N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I, characterized by Fourier-transform infrared spectroscopy (FT-IR) pattern as depicted in Fig-8.
In other embodiment, the present invention provides a crystalline N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I, characterized by FT-IR pattern having peaks at 3326.7, 3293.76, 3173.96, 3070.19, 2986.06, 2950.15, 2870.68, 2819.81, 2775.77, 1709.26, 1696.7, 1651.11, 1626.58 and 1608.68 cm-1.
In another embodiment, the present invention provides a process for preparation of solid form of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts thereof, wherein said process comprising the steps of:
a) adding Omecamtiv Mecarbil or pharmaceutically acceptable salts thereof in a solvent;
b) optionally adding anti-solvent to the solution obtained in step a); and
c) isolating the solid form of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts thereof.
In another embodiment, the present invention provides a process for preparation of crystalline Form MK-1 of Omecamtiv Mecarbil of Formula I, wherein said process comprising the steps of:
a) adding Omecamtiv Mecarbil in solvent(s);
b) heating the reaction mixture at suitable temperature;

c) optionally adding anti-solvent to the solution obtained in step b);
d) cooling the reaction mixture at suitable temperature; and
e) isolating the crystalline Form MK-1 of Omecamtiv Mecarbil.
In another embodiment, the suitable solvent used for preparing crystalline Form MK-1 is selected from, but not limited to N-methyl pyrrolidine, acetonitrile, water, dimethyl acetamide, dimethyl formamide, N-methyl acetamide, acetamide, isopropyl ether, propionitrile, ethyl acetate, toluene, methyl ethyl ketone, methanol, ethanol, isopropanol, acetone and mixture thereof.
In another embodiment, the anti-solvent used for preparing crystalline Form MK-1 is selected from, but not limited to diisopropyl ether, ethoxyethane, methoxyethane, 2-methoxy-2-methyl propane, phenoxybenzene, methanol, cyclohexane, tetrahydrofuran, dioxane, n-heptane, water and mixture thereof.
In another embodiment, the present invention provides a process for preparation of solvate of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts thereof, wherein said process comprising the steps of:
a) adding Omecamtiv Mecarbil in solvent(s);
b) optionally adding anti-solvent to the solution obtained in step a); and
c) isolating the solvate of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts thereof.
In another embodiment, the present invention provides a process for preparation of crystalline N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I, wherein said process comprising the steps of:
a) adding Omecamtiv Mecarbil in N-methylpyrrolidone;
b) heating the reaction mixture at suitable temperature;
c) adding anti-solvent to the solution obtained in step a);
d) cooling the reaction mixture at suitable temperature; and
e) isolating the N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I.

In another embodiment, the present invention provides pharmaceutical acceptable salt of Omecamtiv Mecarbil of Formula I.
In another embodiment, the present invention provides a stable amorphous form of Omecamtiv Mecarbil of Formula I or pharmaceutical acceptable salt thereof.
In another embodiment, the present invention provides a stable amorphous form of organic acid addition salt of Omecamtiv Mecarbil of Formula I.
In another embodiment, the present invention provides a process for the preparation of stable amorphous form of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salt thereof, comprising the steps:
a) dissolving Omecamtiv Mecarbil of Formula I or pharmaceutical acceptable salt thereof in suitable solvent,
b) stirring the reaction mixture to get the clear solution: and
c) isolating the amorphous form of Omecamtiv Mecarbil of Formula I or pharmaceutical acceptable salt thereof.
In another embodiment, the present invention provides a process for the preparation of pharmaceuticalyl acceptable salt of Omecamtiv Mecarbil of Formula I, comprising the steps:
a) dissolving Omecamtiv Mecarbil of Formula I in suitable solvent,
b) adding suitable pharmaceutically acceptable acid,
c) stirring the reaction mixture at suitable temperature; and
d) isolating the pharmaceutically acceptable salt of Omecamtiv Mecarbil of Formula I.
In another embodiment, the present invention provides a process for the purification of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salt thereof, comprising the steps of:
a) providing a solution of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salt thereof in suitable solvent at suitable temperature; and

b) isolating the pure Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salt thereof.
In another embodiment, the present invention provides a process for the purification of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salt thereof, comprising the steps of:
a) providing a solution of Omecamtiv Mecarbil of Formula I in suitable solvent at suitable temperature;
b) adding suitable pharmaceutically acceptable acid to get pharmaceutically acceptable salt of Omecamtiv Mecarbil;
c) adding suitable base to the pharmaceutical acceptable salt of Omecamtiv Mecarbil to get Omecamtiv Mecarbil to free base; and
d) optionally, converting the Omecamtiv Mecarbil free base to its pharmaceutically acceptable salt.
In another embodiment, present invention provides a solid pharmaceutical composition of Omecamtiv Mecarbil or pharmaceutically acceptable salt and one or more pharmaceutically acceptable carrier.
In another embodiment, the Omecamtiv Mecarbil used in the present invention is prepared by any of the conventional methods known in the prior arts.
In a preferred embodiment, the Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts thereof may be isolated from the reaction mixture by purification, centrifugation, crystallization, filtration, extraction, evaporation and lyophilization.
In other embodiment, the solid forms of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts thereof as prepared by the process of the present invention is isolated with purity of 98% or above and preferably, 99% or above.

In another embodiment, the present invention provides the solid forms of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts thereof that is characterized by particle size distribution wherein, d% is 0.1 um to 200um.
In another embodiment, the present invention provides the solid forms of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts thereof that is characterized by particle size distribution wherein, d% is 2.0 um to 150um.
In a preferred embodiment, the solid forms of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts thereof may be isolated from the reaction mixture by purification, centrifugation, crystallization, filtration, extraction or evaporation.
The present invention is explained below by way of examples. However, the examples are provided as one of the possible way to practice the invention and should not be considered as limitation of the scope of the invention.
EXAMPLES
Example-1: Synthesis of crystalline Form MK-1 of Omecamtiv Mecarbil of
Formula I:
Charged N-methylpyrrolidone (7.5 ml) and Omecamtiv Mecarbil (3.0 g) in a round bottom flask and temperature was raised to 80°C until Omecamtiv Mecarbil gets dissolved. Reaction mixture was filtered at 80°C. The filtrate was charged in round bottom flask and diisopropylether (30 ml) was added slowly at 70°C. The reaction mixture was cooled to room temperature and stirred for 3-4 hours. The solid was filtered, washed with diisopropyl ether (5 ml) and dried. The material was dried at 40-45°C and further at 80°C for 5-6 hours to obtained crystalline Form MK-1 of Omecamtiv Mecarbil of Formula I (0.8 g).
Example-2: Synthesis of crystalline N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I:
Charged N-methylpyrrolidone (7.5 ml) and Omecamtiv Mecarbil (3.0 g) in a round bottom flask and temperature was raised to 80°C till Omecamtiv Mecarbil gets

dissolved. Reaction mixture was filtered at 80°C. The filtrate was charged in round bottom flask and diisopropylether (30 ml) was added slowly at 70°C. The reaction mixture was cooled to room temperature and stirred for 3-4 hours. The solid was filtered, washed with diisopropyl ether (5 ml) and dried. The material was dried at 40-45 °C to obtain crystalline N- methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I (2-4 g).
Example-3: Synthesis of amorphous Omecamtiv Mecarbil
Dissolved Omecamtiv Mecarbil (free base) (0.8 g) in a mixture of acetonitrile: water (45 ml:45 ml) at room temperature. Reaction mixture was filtered 0.45 micron filter paper. Cooled the FML to freeze at temperature below -70°C and lyophilized overnight to get amorphous material (0.79 g).
Example-4: Synthesis of Oxalic Acid salt of Omecamtiv Mecarbil:
Dissolved Omecamtiv Mecarbil (free base) (0.5 g) and oxalic acid dihydrate (0.157 g) in a mixture of acetonitrile: water (15ml: 15ml) at room temperature. Reaction mixture was filtered through 0.45 micron filter paper. FML is cooled at temperature below -70°C and lyophilized overnight to get amorphous oxalic acid salt of Omecamtiv Mecarbil (0.64 g).
Example-5: Synthesis of malonic acid salt of Omecamtiv Mecarbil:
Dissolved Omecamtiv Mecarbil (free base) (0.5 g) and malonic acid (0.129 g) in a mixture of acetonitrile: water (20 ml: 20 ml) at room temperature. Reaction mixture was filtered through 0.45 micron filter paper. Cooled the FML to freeze at temperature below -70°C and lyophilized overnight to get amorphous malonic Acid salt of Omecamtiv Mecarbil (0.610 g).
Example-6: Synthesis of succinic acid salt of Omecamtiv Mecarbil:
Dissolved Omecamtiv Mecarbil (free base) (0.5 g) and succinic acid (0.147 g) in a mixture of acetonitrile: water (9 ml: 9 ml) at room temperature. Reaction mixture was filtered through 0.45 micron filter paper. Cooled the FML to freeze at temperature below

-70°C and lyophilized overnight to get amorphous Succinic Acid salt of Omecamtiv Mecarbil (0.620 g).
Example-7: Synthesis of salicylic acid salt of Omecamtiv Mecarbil:
Dissolved Omecamtiv Mecarbil (free base) (0.5 g) and salicylic Acid (0.172 g) in a mixture of acetonitrile: water (18 ml: 18 ml) at room temperature. Reaction mixture was filtered through 0.45 micron filter paper. Cooled the FML to freeze at temperature below -70°C and lyophilized overnight to get amorphous salicylic acid salt of Omecamtiv Mecarbil (0.635 g).
Example-8: Synthesis of citric acid salt of Omecamtiv Mecarbil:
Dissolved Omecamtiv Mecarbil (free base) (0.5 g) and citric acid anhydrous (0.239 g) in a mixture of Acetonitrile: water (18 ml: 18 ml) at room temperature. Reaction mixture was filtered through 0.45 micron filter paper. Cooled the FML to freeze at temperature below -70°C and lyophilized overnight to get amorphous material (0.635 g).
Example-9: Synthesis of D, L- tartaric acid salt of Omecamtiv Mecarbil:
Dissolved Omecamtiv Mecarbil (free base) (0.5 g) and D, L-tartaric acid (0.187 g) in a mixture of acetonitrile: water (25 ml: 25 ml) at room temperature. Reaction mixture was filtered through 0.45 micron filter paper. Cooled the FML to freeze at temperature below -70°C and lyophilize overnight to get amorphous D, L- tartaric acid salt of Omecamtiv Mecarbil (0.670 g).
Example-10: synthesis of D, L- malic acid salt of Omecamtiv Mecarbil:
Dissolved Omecamtiv Mecarbil (free base) (0.3 g) and D,L-Malic Acid (0.100 g) in a mixture of acetonitrile: water (18 ml: 18 ml) at room temperature. Reaction mixture was filtered through 0.45 micron filter paper. Cooled the FML to freeze at temperature below -70°C and lyophilize overnight to get amorphous D,L- Malic acid salt of Omecamtiv Mecarbil (0.385 g).
Example-11: Synthesis of L-malic acid salt of Omecamtiv Mecarbil:

Dissolved Omecamtiv Mecarbil (free base) (0.5 g) and L-malic Acid (0.167 g) in isopropanol at 80°C till clear solution. Reaction mixture was cooled and distilled out under vacuum at 50°C. Charged methanol (25 ml) and water (10 ml) and heated to 50-55°C. Solvent was distilled out at same temperature and chased out with methanol (25 ml). Obtained solid was degassed under vacuum to get amorphous L-malic acid salt of Omecamtiv Mecarbil (0.480 g)
Example-12: Synthesis of nicotinic acid salt of Omecamtiv Mecarbil:
Dissolved Omecamtiv Mecarbil (free base) (0.5 g) and nicotinic Acid (0.153 g) in methanol (40 ml) at room temperature. Reaction mixture was filtered through 0.45 micron filter paper. Solvent was distilled out at 50°C under vacuum and degassed at same temperature to get amorphous nicotinic acid salt of Omecamtiv Mecarbil (0.645 g).
Example-13: Synthesis of S-(+)-mandelic acid salt of Omecamtiv Mecarbil:
Dissolved Omecamtiv Mecarbil (free base) (0.5 g) and S-(+)-mandalic Acid (0.303 g) in isopropanol at 80°C till clear solution. Reaction mixture was filtered 0.45 micron filter paper. Solvent was distilled out at 60°C under vacuum and degassed at same temperature to get amorphous S-(+)-mandalic acid salt of Omecamtiv Mecarbil (0.8 g).
Example 14: Synthesis of amorphous form of Omecamtiv Mecarbil of Formula I:
Charged Isopropanol (5ml), water (10.0 ml) and Omecamtiv Mecarbil (2.0 g) in a round bottom flask at 20-25°C. Stirred the reaction mass for 10-15 minutes at 20-25°C and lyophilized to get amorphous form of Omecamtiv Mecarbil of Formula I (1.6 g)

WE CLAIM:

1. A process for preparation of solid form of Omecamtiv Mecarbil of Formula I or
pharmaceutically acceptable salts thereof, wherein said process comprising the steps of:
a) adding Omecamtiv Mecarbil or pharmaceutically acceptable salts thereof in a solvent;
b) optionally adding anti-solvent to the solution obtained in step a); and
c) isolating the solid form of Omecamtiv Mecarbil of Formula I or pharmaceutically acceptable salts thereof.
2. A process for preparation of crystalline Form MK-1 of Omecamtiv Mecarbil of
Formula I, wherein said process comprising the steps of:
a) adding Omecamtiv Mecarbil in solvent(s);
b) heating the reaction mixture at suitable temperature;
c) optionally adding anti-solvent to the solution obtained in step b);
d) cooling the reaction mixture at suitable temperature; and
e) isolating the crystalline Form MK-1 of Omecamtiv Mecarbil.

3. The process as claimed in claim 2, wherein said crystalline Form MK-1 is characterized by XRPD having peaks selected from (29 values) at 6.38, 13.02, 18.76 and 21.09 ±O.2°0.
4. The process as claimed in claim 2, wherein said suitable solvent N- methyl pyrrolidine, acetonitrile, water, dimethyl acetamide, dimethyl formamide, N-methyl acetamide, acetamide, isopropyl ether, propionitrile, ethyl acetate, toluene, methyl ethyl ketone, methanol, ethanol, isopropanol, acetone and mixture thereof.
5. The process as claimed in claim 2, wherein said anti-solvent is selected from diisopropyl ether, ethoxyethane, methoxy ethane, 2-methoxy-2-methyl propane, phenoxybenzene, methanol, cyclohexane, tetrahydrofuran, dioxane, n-heptane, water and mixture thereof.

6. The process as claimed in claim 1, wherein said pharmaceutically acceptable salts are
prepared by a process the steps:
a) dissolving Omecamtiv Mecarbil of Formula I in suitable solvent,
b) adding suitable pharmaceutically acceptable acid,
c) stirring the reaction mixture at suitable temperature; and
d) isolating the pharmaceutically acceptable salt of Omecamtiv Mecarbil.

7. The process as claimed in claim 6, wherein said pharmaceutically acceptable acid is selected from oxalic acid, malonic acid, succinic acid, salicylic acid, citric acid, D,L-tartaric acid, D,L-malic acid, L-malic acid, nicotinic acid, and S-(+)-mandalic acid.
8. The process as claimed in claim 6, wherein said suitable solvent used in step a) is selected from mixture of acetonitrile and water, isopropanol, methanol, ethanol, mixture of propionitrile and water, and N-methylpyrrolidine.
9. A process for preparation of crystalline N-methylpyrrolidone solvate of Omecamtiv Mecarbil of Formula I, wherein said process comprising the steps of:

a) adding Omecamtiv Mecarbil in N-methylpyrrolidone;
b) heating the reaction mixture at suitable temperature;
c) adding anti-solvent to the solution obtained in step b);
d) cooling the reaction mixture at suitable temperature; and
e) isolating the N-methylpyrrolidone solvate of Omecamtiv Mecarbil.
10. The process as claimed in claim 9, wherein the anti-solvent used in step c) is selected
from diisopropyl ether, ethoxyethane, methoxyethane, 2-methoxy-2-methyl propane,
phenoxybenzene, methanol, cyclohexane, tetrahydrofuran, dioxane, n-heptane, water
and mixture thereof.