Abstract:
The present invention provides novel crystalline hydrochloride salt of darunavir, process for its preparation and to pharmaceutical composition comprising it. The present invention also provides novel process for preparation of darunavir amorphous form and pharmaceutical composition comprising it.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. application Ser. No. 13/699,096, filed on Feb. 7, 2013, which is a 371 of PCT/IN2010/000339 filed May 20, 2010, under the provisions of 35 U.S.C. 119 and the International Convention for the protection of Industrial Property, which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention provides novel crystalline hydrochloride salt of darunavir, process for its preparation and to pharmaceutical composition comprising it. The present invention also provides novel process for preparation of darunavir amorphous form and pharmaceutical composition comprising it. 
       BACKGROUND OF THE INVENTION 
       [0003]    Virus-encoded proteases, which are essential for viral replication, are required for the processing of viral protein precursors. Interference with the processing of protein precursors inhibits the formation of infectious virions. Accordingly, inhibitors of viral proteases may be used to prevent or treat chronic and acute viral infections. Darunavir has HIV protease inhibitory activity and is particularly well suited for inhibiting HIV-1 and HIV-2 viruses. Among them darunavir, chemically (1S,2R,3′R,3′aS,6′aR)-[3′-hexahydrofuro[2,3-b]furanyl-[3-(4-aminobenzenesulfonyl)isobutylamino]-1-benzyl-2-hydroxypropyl]carbamate. Darunavir is represented by the following structure: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0004]    Darunavir and its pharmaceutical acceptable salts such as hydrochloride were described in EP 715618. 
         [0005]    Processes for the preparations of darunavir were disclosed in EP 715618, WO 99/67417, U.S. Pat. No. 6,248,775, and in Bioorganic and Chemistry Letters, Vol. 8, pp. 687-690, 1998, “Potent HIV protease inhibitors incorporating high-affinity P2-igands and (R)-(hydroxyethylamino)sulfonamide isostere”, all of which are incorporated herein by reference. 
         [0006]    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 molecules 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 different 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). 
         [0007]    Darunavir or its hydrochloride salt can exist in different polymorphic forms, which may differ from each other in terms of stability, physical properties, spectral data and methods of preparation. 
         [0008]    U.S. Patent Application No. 2005/0250845 described amorphous form, form A (ethanolate), form B (hydrate), form C (methanolate), form D (acetonate), form E (dichloromethanate), form F (ethylacetate solvate), form G (1-ethoxy-2-propanolate), form H (anisolate), form I (tetrahydrofuranate), form J (isopropanolate) and form K (mesylate) of darunavir. 
         [0009]    Darunavir C 5 -C 8  alcohol solvate and process for its preparation was disclosed in co-pending Application No. PCT/IN2009/000724. According to the application also disclosed a process for the preparation of darunavir amorphous form which comprises a solution of darunavir C 5 -C 8  alcohol solvate in dichloromethane, removing the solvent from the solution to obtain a residue, slurrying the residue with cyclohexane and isolating. 
         [0010]    We have discovered novel crystalline hydrochloride salt of darunavir and also discovered novel process for the preparation of darunavir amorphous form. 
         [0011]    Thus, one object of the present invention is to provide novel crystalline hydrochloride salt of darunavir, process for its preparation and to pharmaceutical compositions comprising it. 
         [0012]    The salt of the present invention may also serve as intermediates for preparation of darunavir amorphous form and other polymorphs of darunavir. 
         [0013]    Another object of the present invention is to provide a novel process for preparation of darunavir amorphous form and pharmaceutical compositions comprising it. 
       SUMMARY OF THE INVENTION 
       [0014]    In one aspect, the present invention provides a crystalline hydrochloride salt of darunavir. 
         [0015]    In another aspect, the present invention provides a process for the preparation of crystalline hydrochloride salt of darunavir, which comprises:
       a) providing a solution of darunavir in a solvent;   b) adding hydrochloric acid to the solution obtained in step (a);   c) slurrying the reaction mass obtained in step (b) at below 40° C.; and   d) isolating crystalline hydrochloride salt of darunavir.       
 
         [0020]    In another aspect, the present invention provides a pharmaceutical composition comprising crystalline hydrochloride salt of darunavir and a pharmaceutically acceptable excipient. 
         [0021]    In another aspect, the present invention provides a process for the preparation of darunavir amorphous form, which comprises:
       a) dissolving darunavir or pharmaceutical acceptable salts in a solvent and water;   b) adjusting the pH of the reaction mass to about 7.0 to 8.5 with a base;   c) removing the solvent from the solution obtained in step (b) to obtain a residual mass;   d) slurrying the residual mass obtained in step (b) with aliphatic hydrocarbon solvent or aromatic solvent; and   e) isolating darunavir amorphous form.       
 
         [0027]    In yet another aspect, the present invention provides a pharmaceutical composition comprising darunavir amorphous form and a pharmaceutically acceptable excipient. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  is X-ray powder diffraction spectrum of crystalline hydrochloride salt of darunavir. 
           [0029]      FIG. 2  is X-ray powder diffraction spectrum of darunavir amorphous form. 
       
    
    
       [0030]    X-ray powder diffraction spectrum was measured on a bruker axs D8 advance X-ray powder diffractometer having a copper-Kα radiation. Approximately 1 gm of sample was gently flattered on a sample holder and scanned from 2 to 50 degrees two-theta, at 0.02 degrees to theta per step and a step of 10.4 seconds. The sample was simply placed on the sample holder. The sample was rotated at 30 rpm at a voltage 40 KV and current 35 mA. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    According to one aspect of the present invention, there is provided a crystalline hydrochloride salt of darunavir. 
         [0032]    Crystalline hydrochloride salt of darunavir which is characterized by peaks in the powder x-ray diffraction spectrum having 2θ angle positions at about 6.7, 8.0, 13.1, 13.9, 14.9, 19.6, 19.9, 24.5 and 27.9±0.2 degrees. The powdered x-ray diffractogram (PXRD) of crystalline hydrochloride salt of darunavir is shown in  FIG. 1 . 
         [0033]    According to another aspect of the present invention, there is provided a process for the preparation of crystalline hydrochloride salt of darunavir, which comprises:
       a) providing a solution of darunavir in a solvent;   b) adding hydrochloric acid to the solution obtained in step (a);   c) slurrying the reaction mass obtained in step (b) at below 40° C.; and   d) isolating crystalline hydrochloride salt of darunavir.       
 
         [0038]    The solvent used in step (a) may preferably be a solvent or mixture of solvents selected from the group consisting of water; a halogenated hydrocarbon solvents such as dichloromethane, chloroform, carbontetrachloride and ethylene dichloride; an ester solvents such as ethyl acetate, methyl acetate, isopropyl acetate, tert-butyl methyl acetate and ethyl formate; a ketonic solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diethyl ketone; an ether solvents such as tetrahydrofuran, 1,4-dioxane, methyl tert-butyl ether, diisopropyl ether and diethyl ether. More preferable solvent is water, dichloromethane, ethyl acetate, methyl isobutyl ketone, methyl tert-butyl ether and diisopropyl ether. 
         [0039]    Darunavir used in step (a) may be darunavir in any solvated or hydrated or anhydrous form and preferably the darunavir is darunavir C 5 -C 8  alcohol solvate such as 2-methyl-2-butanol solvate or n-pentanol solvate, darunavir ethanolate and anhydrous form of darunavir. 
         [0040]    Hydrochloric acid can be used in step (b) as an aqueous hydrochloric acid or anhydrous hydrochloric acid and preferably aqueous hydrochloric acid is used. 
         [0041]    Preferably the slurrying may be carried out at room temperature for at least 30 minutes. 
         [0042]    The isolation of crystalline hydrochloride salt of darunavir in step (d) may preferably be performed by conventional techniques such as centrifugation and filtration. 
         [0043]    According to another aspect of the present invention, there is provided a pharmaceutical composition which comprises crystalline hydrochloride salt of darunavir and pharmaceutically acceptable carriers, diluents or excipients and optionally other therapeutic ingredients. The salt may preferable be conveniently formulated into tablets, capsules, suspensions, dispersions, injectables and other pharmaceutical forms. 
         [0044]    According to another aspect of the present invention, there is provided a process for the preparation of darunavir amorphous form, which comprises:
       a) dissolving darunavir or pharmaceutical acceptable salts in a solvent and water;   b) adjusting the pH of the reaction mass to about 7.0 to 8.5 with a base;   c) removing the solvent from the solution obtained in step (b) to obtain a residual mass;   d) slurrying the residual mass obtained in step (b) with aliphatic hydrocarbon solvent or aromatic solvent; and   e) isolating darunavir amorphous form.       
 
         [0050]    Darunavir or its pharmaceutical acceptable salts used in step (a) is crystalline hydrochloride salt of darunavir. 
         [0051]    The solvent used in step (a) may preferably be a solvent or mixture of solvents selected from the group consisting of a halogenated hydrocarbon solvents such as dichloromethane, chloroform, carbontetrachloride and ethylene dichloride; an ester solvents such as ethyl acetate, methyl acetate, isopropyl acetate, tert-butyl methyl acetate and ethyl formate; a ketonic solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diethyl ketone; an ether solvents such as tetrahydrofuran, 1,4-dioxane, methyl tert-butyl ether, diisopropyl ether and diethyl ether. More preferable solvent is dichloromethane, ethyl acetate, methyl isobutyl ketone, methyl tert-butyl ether and diisopropyl ether. 
         [0052]    Preferably the pH of the reaction mass in step (b) may be adjusted to 7.2-8.2 and more preferably the pH adjusted to 7.5-8.0. 
         [0053]    The base used in step (b) may preferably be an organic base or an inorganic base selected from ammonium, sodium hydroxide and potassium hydroxide, and more preferably the base is ammonia. 
         [0054]    Removal of the solvent may be carried out in step (c) at atmospheric pressure or at reduced pressure. Removal of the solvent may preferably be carried out until the solvent is almost completely distilled off. 
         [0055]    The aliphatic hydrocarbon solvent or aromatic solvent used in step (d) may preferably be a solvent or a mixture of solvents selected from cyclohexane, hexane, n-heptane, toluene and xylene. More preferable aliphatic hydrocarbon solvent is cyclohexane. 
         [0056]    The isolation of darunavir amorphous form in step (e) may preferably be performed by conventional techniques such as centrifugation and filtration. 
         [0057]    According to another aspect of the present invention, there is provided a pharmaceutical composition comprising a darunavir amorphous form and a pharmaceutically acceptable excipient. 
         [0058]    The pharmaceutically acceptable inert carrier which can be used may be a solid dosage forms. 
         [0059]    The solid dosage forms for oral administration may include capsules, tablets, pills, powders and granules. 
         [0060]    The invention will now be further described by the following examples, which are illustrative rather than limiting. 
       EXAMPLES 
     Example 1 
     Preparation of Crystalline Hydrochloride Salt of Darunavir 
       [0061]    To a mixture of (3R,3aS,6aR)-hexahydrofuro [2,3-b]furan-3-ol (66 gm) and acetonitrile (300 ml) was added disuccinimidyl carbonate (110 gm) at 25 to 30° C. The reaction mass was cooled to 10° C. under nitrogen atmosphere and then added pyridine (93 gm) for 30 minutes. The temperature of the reaction mass was raised to 30° C. and stirred for 1 hour 30 minutes at 30° C. The reaction mass further cooled to −10° C. under nitrogen atmosphere. A solution of 4-amino-N-((2R,3 S)-3-amino-2-hydroxy-4-phenylbutyl)-N-(isobutyl)benzene sulfonamide (135 gm) in acetonitrile (330 ml) was added to the reaction mass at −10to −15° C. for 45 minutes. To the reaction mass was added triethylamine (39 gm) and monomethylamine (5.8 gm) at −10° C., and the temperature was slowly raised to 20 to 25° C. and stirred for 1 hour. The reaction mass distilled off the solvent completely removed under vacuum at below 50° C. to obtain a residue. To the residue was added dichloromethane (1000 ml). The dichloromethane layer was washed with 10% sodium bicarbonate (500 ml), 2% sulfuric acid (500 ml), 10% sodium sulfate (500 ml) and 10% sodium chloride solution (500 ml). The layer was treated with carbon and then added concentrated hydrochloric acid (40 ml). The reaction mass was stirred for 1 hour at 25 to 30° C. and filtered. The solid obtained was dried under vacuum at 60 to 65° C. for 6 hours to obtain 140 gm of crystalline hydrochloride salt of darunavir. 
       Example 2 
     Preparation of Crystalline Hydrochloride Salt of Darunavir 
       [0062]    Darunavir 2-methyl-2-butanol solvate (100 gm) was dissolved in dichloromethane (1000 ml) and stirred to obtain a solution. To the solution was added concentrated hydrochloric acid (30 ml) and stirred for 1 hour at 25 to 30° C. The separated solid was filtered and dried under vacuum at 60 to 65° C. for 6 hours to obtain 97 gm of crystalline hydrochloride salt of darunavir. 
       Example 3 
     Preparation of Crystalline Hydrochloride Salt of Darunavir 
       [0063]    Darunavir n-pentanol solvate (50 gm) was dissolved in dichloromethane (500 ml) and water (50 ml) under stirring. To the solution was added concentrated hydrochloric acid (20 ml) and stirred for 1 hour at 25 to 30° C. The separated solid was filtered and dried under vacuum at 60 to 65° C. for 6 hours to obtain 45 gm of crystalline hydrochloride salt of darunavir. 
       Example 4 
     Preparation of Crystalline Hydrochloride Salt of Darunavir 
       [0064]    Darunavir (10 gm) was dissolved in dichloromethane (100 ml) and stirred to obtain a solution. To the solution was added concentrated hydrochloric acid (3 ml) and stirred for 1 hour at 25 to 30° C. The separated solid was filtered and dried under vacuum at 60 to 65° C. for 6 hours to obtain 9.8 gm of crystalline hydrochloride salt of darunavir. 
       Example 5 
     Preparation of Crystalline Hydrochloride Salt of Darunavir 
       [0065]    Darunavir ethanolate (100 gm) was dissolved in ethyl acetate (1000 ml) and stirred to obtain a solution. To the solution was added concentrated hydrochloric acid (30 ml) and stirred for 1 hour at 25 to 30° C. The separated solid was filtered and dried under vacuum at 60 to 65° C. for 6 hours to obtain 95 gm of crystalline hydrochloride salt of darunavir. 
       Example 6 
     Preparation of Crystalline Hydrochloride Salt of Darunavir 
       [0066]    Example 4 was repeated using ethyl acetate solvent instead of dichloromethane solvent to obtain crystalline hydrochloride salt of darunavir. 
       Example 7 
     Preparation of Crystalline Hydrochloride Salt of Darunavir 
       [0067]    Example 4 was repeated using methyl tert-butyl ether solvent instead of dichloromethane solvent to obtain crystalline hydrochloride salt of darunavir. 
       Example 8 
     Preparation of Crystalline Hydrochloride Salt of Darunavir 
       [0068]    Example 4 was repeated using methyl isobutyl ketone solvent instead of dichloromethane solvent to obtain crystalline hydrochloride salt of darunavir. 
       Example 9 
     Preparation of Crystalline Hydrochloride Salt of Darunavir 
       [0069]    Example 4 was repeated using diisopropyl ether solvent instead of dichloromethane solvent to obtain crystalline hydrochloride salt of darunavir. 
       Example 10 
     Preparation of Darunavir Amorphous Form 
       [0070]    Crystalline hydrochloride salt of darunavir (135 gm) as obtained in example 1 was dissolved in dichloromethane (1200 ml) and water (1000 ml) at room temperature. The pH of the reaction mass was adjusted to 7.5 to 8.0 with ammonium solution and stirred for 20 minutes. The organic layer was treated with carbon and distilled off the solvent completely under vacuum at 45° C. to obtain foam like residue. Cyclohexane (1000 ml) was added to the residue, distilled off the solvent completely under vacuum at 45° C. to obtain residue. To the residue was added cyclohexane (100 ml) and stirred for 4 hours at 20 to 25° C. The separated solid was filtered and dried under vacuum at 50° C. for 12 hours to obtain 120 gm of darunavir amorphous form. 
       Example 11 
     Preparation of Darunavir Amorphous Form 
       [0071]    Crystalline hydrochloride salt of darunavir (5 gm) was dissolved in ethyl acetate (50 ml) and water (50 ml) at room temperature. The pH of the reaction mass was adjusted to 7.5 to 8.0 with ammonium solution and stirred for 20 minutes. The organic layer was treated with carbon and distilled off the solvent under vacuum at 45° C. to obtain foam like residue. Cyclohexane (25 ml) was added to the residue, distilled off the solvent completely under vacuum at 45° C. to obtain a residue. To the residue was added cyclohexane (50 ml) and stirred for 5 hours at 25 to 30° C., filtered. The solid obtained was dried under vacuum at 50° C. for 12 hours to obtain 4.2 gm of darunavir amorphous form. 
       Example 12 
     Preparation of Darunavir Amorphous Form 
       [0072]    Example 10 was repeated using methyl tert-butyl ether solvent instead of dichloromethane solvent to obtain darunavir amorphous form. 
       Example 13 
     Preparation of Darunavir Amorphous Form 
       [0073]    Example 10 was repeated using methyl isobutyl ketone solvent instead of dichloromethane solvent to obtain darunavir amorphous form.