DESC: RELATED APPLICATION:
This application claims the benefit of priority of our Indian patent application number IN 201721000754 dated Jan. 09, 2017, which is incorporated herein by reference.
FIELD OF THE INVENTION
The present invention provides a novel crystalline form of Daclatasvir dihydrochloride and process for preparation thereof.
BACKGROUND OF THE INVENTION
Daclatasvir dihydrochloride (DAKLINZA) is an inhibitor of HCV nonstructural protein 5A (NS5A) and is indicated for use with sofosbuvir, with or without ribavirin, for the treatment of patients with chronic hepatitis C virus (HCV) genotype 1 or genotype 3 infection.

US8329159B2 ( ) patent discloses Daclatasvir and also its preparation method. Patent US8629171B2 discloses crystalline form N-2 of Daclatasvir dihydrochloride and its preparation. US7728027B2 patent ( ) discloses process for preparation of Daclatasvir dihydrochloride.
Polymorphism is defined as "the ability of a substance to exist as two or more crystalline phases that have different arrangement and/or conformations of the molecule in the crystal lattice. Thus, in the strict sense, polymorphs are different crystalline forms of the same pure substance in which the molecules have different arrangements and/or configurations of the molecules". Different polymorphs may differ in their physical properties such as melting point, solubility, X-ray diffraction patterns, etc. Although those differences disappear once the compound is dissolved, they can appreciably influence pharmaceutically relevant properties of the solid form, such as handling properties, dissolution rate and stability. Such properties can significantly influence the processing, shelf life, and commercial acceptance of a polymorph. It is therefore important to investigate all solid forms of a drug, including all polymorphic forms, and to determine the stability, dissolution and flow properties of each polymorphic form. Polymorphic forms of a compound can be distinguished in the laboratory by analytical methods such as X-ray diffraction (XRD), differential Scanning Calorimetry (DSC) and infrared spectrometry (IR). Solvent medium and mode of isolation play very important role in obtaining a polymorphic form over the other.
Accordingly, there remains a need in the art for a novel, stable and substantially pure crystalline form of Daclatasvir dihydrochloride.
SUMMARY OF THE INVENTION
One aspect of the present invention provides a novel, substantially pure and stable crystalline form Al-1 of Daclatasvir dihydrochloride of Formula (I).

Another aspect of the present invention provides a novel, pure and stable crystalline form Al-1 of Daclatasvir dihydrochloride characterized by X-ray diffraction pattern as depicted in Fig-1.
Yet another aspect of the present invention further encompasses a process for preparing the highly pure and stable crystalline form Al-1 of Daclatasvir dihydrochloride.
Still yet another aspect of the present invention provides a pharmaceutical composition comprising crystalline Daclatasvir dihydrochloride Al-1 of the present invention and one or more pharmaceutically acceptable excipients.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig 1 shows the X-ray powder diffractogram ("PXRD") pattern of Daclatasvir dihydrochloride crystalline form Al-1.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, the term “substantially pure” with reference to a particular polymorphic form means that the polymorphic form includes less than 30%, less than 25%, less than 20%, less than 15%, less than 10%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1% by weight of any other physical forms of the compound.
One aspect of the present invention relates to a novel crystalline form of Daclatasvir dihydrochloride of Formula (I)
Another aspect of the present invention relates to a novel crystalline form Al-1 of Daclatasvir dihydrochloride having one or more PXRD peaks (2?) at approximate positions: 8.30, 9.57, 15.38, 19.05, 22.29, 23.28 and 24.78 ± 0.2 degrees.
In an embodiment of the invention the novel crystalline form Al-1 of Daclatasvir dihydrochloride is characterized by having one or more PXRD peaks 2theta angle (2? ±0.2) approximately at: 8.30, 8.61, 9.57, 10.61, 11.10, 12.91, 13.23, 13.65, 14.94, 15.17, 15.38, 16.56, 17.27, 17.95, 18.42, 19.05, 19.22, 21.08, 21.34, 21.59, 22.29, 22.60, 22.94, 23.28, 23.67, 24.19, 24.33, 24.78, 25.39, 25.97, 26.55, 26.86, 27.95, 28.29, 28.75, 29.10, 29.53, 30.01, 30.64, 31.36, 31.59, 32.22, 32.69, 33.61, 34.55, 35.01, 36.15, 36.49, 37.82 and 38.49 ± 0.2 degrees.
In another embodiment of the invention the novel crystalline form Al-1 of Daclatasvir dihydrochloride is illustrated by X-ray powder diffractogram ("PXRD") peaks as shown in Fig-1.
In one embodiment of the invention, a process is provided for preparation of novel crystalline form Al-1 of Daclatasvir dihydrochloride comprising steps of providing a solution of Daclatasvir dihydrochloride in a suitable solvent or a mixture of solvents and then isolating the crystalline form.
In another embodiment of the present invention there is provided a method for the preparation of crystalline form Al-1 Daclatasvir dihydrochloride of formula (I) comprising:
a. providing solution of Daclatasvir dihydrochloride salt in a suitable solvent at a suitable temperature; and
b. isolating the crystalline form Al-1 Daclatasvir dihydrochloride.
wherein, the suitable solvent is selected from water.
In an embodiment of the invention, the step of providing a solution of Daclatasvir diHCl salt in a suitable solvent is achieved by 1) dissolving Daclatasvir dihydrochloride in water; 2) preparing Daclatasvir dihydrochloride by treating Daclatasvir with hydrochloric acid (either conc. HCl or diluted HCl) in water. The Daclatasvir can be obtained in the course of its synthesis as a residue or in a solid form.
In some embodiments, the suitable temperature may range from RT to about the reflux temperature of the solvent used, or from about 30 °C to about 80 °C or any temperatures range that doesn’t affect the quality of the product to be obtained. Preferably temperature is about 65 °C.
In an embodiment of the invention, isolating the crystalline form may include cooling, concentrating the mass, adding an anti-solvent, adding seed crystals to induce crystallization or the like. Stirring or other alternate methods such as shaking, agitation, or the like, may also be employed for the isolation. The water used in the reaction mass may be optionally distilled partially to get the maximum yield before cooling the reaction mass.
In few embodiments of the invention, the isolated may be recovered by methods including decantation, centrifugation, gravity filtration, suction filtration, or any other technique for the recovery of solids under pressure or under reduced pressure. The recovered solid may optionally be dried. Drying may be carried out in a tray dryer, vacuum oven, air oven, cone vacuum dryer, rotary vacuum dryer, fluidized bed dryer, spin flash dryer, flash dryer, or the like. The drying may be carried out at temperatures less than about 100° C, less than about 80° C, less than about 60° C, less than about 50° C, less than about 30° C, or any other suitable temperatures, at atmospheric pressure or under a reduced pressure, as long as the formed crystalline Daclatasvir diHCl is not degraded in quality.
In few embodiments of the invention, the dried product may optionally be subjected to a size reduction procedure to produce desired particle sizes. Milling or micronization may be performed before drying, or after the completion of drying of the product. Techniques that may be used for particle size reduction include, without limitation, ball, roller and hammer milling, and jet milling.
Wherever applicable in the example of the present invention, the reaction solution may optionally be treated with carbon, flux-calcined diatomaceous earth (Hyflow) or any other suitable material to remove color, insoluble materials, improve clarity of the solution, and/or remove impurities adsorbable on such material.
In another embodiment of the present invention, the suitable solvent included but not limited to water, esters, alkanols, aliphatic and cyclic hydrocarbons, halogenated hydrocarbons, ketones, ethers, polar aprotic solvents, or mixtures thereof. The esters may include one or more of ethyl acetate, n-propyl acetate, isopropyl acetate, and n-butyl acetate. Examples of alkanols include those primary, secondary and tertiary alcohols having from one to six carbon atoms. Suitable alkanol solvents include methanol, ethanol, n-propanol, isopropanol and butanol. Examples of aliphatic hydrocarbons include hexane, heptane, and octane. Examples of cyclic hydrocarbons include cyclohexane, cycloheptane and cyclooctane. Examples of halogenated hydrocarbons include dichloromethane, chloroform, and 1,2-dichloroethane. Examples of ketones include acetone, methyl ethyl ketone, and the like. Examples of ethers include diethyl ether, methyl tert-butyl ether, cyclopentyl methyl ether, tetrahydrofuran, and the like. A suitable polar aprotic solvent includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulphoxide, acetonitrile and N-methylpyrrolidone. Preferably, water.
The crystalline form Al-1 of Daclatasvir dihydrochloride obtained according to the present invention were subjected to stability studies under following conditions as shown in the below table
Condition Results
25°C/60%RH(3 months) Substantially same PXRD as fig 1
40°C/75%RH(3 months) Substantially same PXRD as fig 1

The results from the above table show that crystalline Form A1-1 is stable in long-term stability (25 ? / 60% RH) and under accelerated stability (40 ? / 75% RH) conditions.
Another aspect of the invention relates to pharmaceutical compositions comprising substantially pure crystalline form Al-1 of Daclatasvir dihydrochloride and one or more pharmaceutically acceptable excipients.
In some embodiments, the pharmaceutically acceptable excipients which can be used include, but are not limited to: diluents such as starches, pregelatinized starches, lactose, powdered celluloses, microcrystalline celluloses, dicalcium phosphate, tricalcium phosphate, mannitol, sorbitol, sugar and the like; binders such as acacia, guar gum, tragacanth, gelatin, polyvinylpyrrolidones, copovidone, hydroxypropyl celluloses, hydroxypropyl methylcelluloses, pregelatinized starches and the like; disintegrants such as starches, sodium starch glycolate, pregelatinized starches, crospovidones, croscarmellose sodium, colloidal silicon dioxide and the like; lubricants such as stearic acid, magnesium stearate, zinc stearate and the like; glidants such as colloidal silicon dioxide and the like; solubility or wetting enhancers such as anionic or cationic or neutral surfactants; complex forming agents such as various grades of cyclodextrins and resins; release rate controlling agents such as hydroxypropyl celluloses, hydroxymethyl celluloses, hydroxypropyl methylcelluloses, ethylcelluloses, ethylcelluloses, various grades of methyl methacrylates, waxes and the like and other pharmaceutical excipients such as film formers, plasticizers, colorants, flavoring agents, sweeteners, viscosity enhancers, syloids, preservatives, antioxidants, and the like.
In some embodiments of the invention, the X-Ray powder diffractograms were measured on a PANalytical X'Pert PRO XRay diffractometer using CuKa1 radiation. The samples were measured in reflection mode in the 2?-range 2.5-40° using an X' celerator detector.
The invention is further exemplified by the following non-limiting examples, which are illustrative representing the preferred modes of carrying out the invention. The invention's scope is not limited to these specific embodiments only but should be read in conjunction with what is disclosed anywhere else in the specification together with those information and knowledge which are within the general understanding of the person skilled in the art.
Examples
Example 1: Preparation of Daclatasvir dihydrochloride crystalline form Al-1
Daclatasvir dihydrochloride (25 g) and water (50 ml) are charged into a reaction vessel and reaction mixture was heated at 60-70 °C for 1-2 h. The resulting solution was cooled gradually and stirred for 3-5 h. The obtained solid was filtered and dried for 15-20 h to obtain Daclatasvir dihydrochloride (22 g) crystalline form with PXRD as shown in Fig-1.
Example 2: Preparation of Daclatasvir dihydrochloride crystalline form Al-1
Daclatasvir base and hydrochloric acid are charged into a reaction vessel and reaction mixture was heated to get a solution. Water was charged into the reaction vessel and reaction mixture was heated at 60-70 °C for 1-2 h. The solution was distilled off under vacuum to obtain Daclatasvir dihydrochloride having PXRD as shown in Fig-1.
Example 3: Preparation of Daclatasvir dihydrochloride crystalline form Al-1
The reaction mixture Daclatasvir (376 gm), water (1.65 litre) and 108 ml of conc. HCl was heated to 65 °C for 3 hours, then cooled to 23 °C and stirred overnight at this temperature. The precipitated solid was filtered, washed with water and dried at 52 °C for 8 hours to obtain Daclatasvir dihydrochloride having PXRD as shown in Fig-1.
Reference Example 1: Preparation of Daclatasvir
To a reaction mass PTSA salt of Daclatasvir (550 gm) in water (550 ml) and ethyl acetate (1.65 liter) saturated solution of sodium bicarbonate (1.65 litre) were added slowly and stirred. The layers were separated, organic layers was washed with water, and distilled to obtain Daclatasvir (417 gms). ,CLAIMS:We Claim:
1. Crystalline form Al-1 of Daclatasvir dihydrochloride of formula (I) having an X-ray powder diffractogram comprising at least one peak at diffraction 2-theta angle (2? ±0.2) selected from 8.30, 9.57, 15.38, 19.05, 22.29, 23.28 and 24.78 ± 0.2.

2. The crystalline form as claimed in claim 1, further characterized having X-ray powder diffractogram peak as shown in Fig 1.

3. A process for preparation of crystalline form Al-1 Daclatasvir dihydrochloride of formula (I) comprising:
a. providing solution of Daclatasvir dihydrochloride salt in a suitable solvent at a temperature in the range of 30 to 80° C; and
b. isolating the crystalline form Al-1 Daclatasvir dihydrochloride.
wherein, the suitable solvent is selected from water.
4. The crystalline form Al-1 Daclatasvir dihydrochloride obtained according to process claimed in claim 3, is characterized having X-ray powder diffractogram peak comprising at least one peak at diffraction 2? angle (2? ±0.2) selected from 8.30, 9.57, 15.38, 19.05, 22.29, 23.28 and 24.78 ± 0.2.

5. The process as claimed in claim 3, wherein the isolation is done by cooling the reaction mass.

6. A pharmaceutical composition comprising crystalline form Al-1 of Daclatasvir dihydrochloride as claimed in claim 1, and one or more pharmaceutically acceptable excipients.