Abstract:
The present invention relates to a novel amorphous form of valsartan, to a process for its preparation and to a pharmaceutical composition containing it.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a novel amorphous form of valsartan, to a process for its preparation and to a pharmaceutical composition containing it.  
       BACKGROUND OF THE INVENTION  
       [0002]     Valsartan of formula (1):  
                         
 
 or N-(1-Oxopentyl)-N-[[2′-(1H-tetrazol-5-yl)[1,1′-biphenyl]-4-yl]methyl]-L-valine, is an antihypertensive agent and its therapeutic uses are disclosed in U.S. Pat. No. 5,399,578. No polymorphs of valsartan are reported in the literature. 
 
         [0003]     We discovered a sufficiently stable amorphous form of valsartan, which is found to be suitable for pharmaceutical composition.  
         [0004]     The object of the present invention is to provide a novel stable amorphous form of valsartan, process the preparing it and a pharmaceutical composition containing it.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0005]     The present invention provides a novel amorphous form of valsartan (hereinafter referred to as amorphous valsartan). The amorphous valsartan is characterized by having broad x-ray diffraction spectrum as in  FIG. 1 .  
         [0006]     A further aspect of the present invention provides a process for the preparation of amorphous valsartan. Amorphous valsartan is prepared by dissolving valsartan in an alcohol or a mixture of alcohols. The alcohol is selected from the group consisting of methanol, ethanol, isopropyl alcohol, tert-butyl alcohol and n-butyl alcohol. The solvent may be removed from the solution by vacuum drying or spray drying.  
         [0007]     A further aspect of the present invention provides a pharmaceutical composition comprising amorphous valsartan and a pharmaceutically acceptable carrier. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a x-ray powder diffraction spectrum of amorphous valsartan. 
        x-Ray powder diffraction spectrum was measured on a Siemens D5000 x-ray powder diffractometer having a copper-Kα radiation.         
     
    
       [0010]     The following examples further illustrate the invention.  
       EXAMPLE 1  
       [0011]     Valsartan (10 gm), (obtained by the process described in example-16 of U.S. Pat. No. 5,399,578) is dissolved in methanol (50 ml). The solution is subjected to vacuum drying at about 40° C. for 10 hours to give 9.8 gm of amorphous valsartan.  
       EXAMPLE 2  
       [0012]     Example 1 is repeated by subjecting the solution to spray drying instead of vacuum drying to give amorphous valsartan.  
       EXAMPLE 3  
       [0013]     Valsartan (10 gm), (obtained by the process described in example-16 of U.S. Pat. No. 5,399,578) is dissolved in ethanol (60 ml). The solution is subjected to vacuum drying at about 45° C. for 12 hours to give 9.7 gm of amorphous valsartan.  
       EXAMPLE 4  
       [0014]     Example 3 is repeated by subjecting the solution to spray drying instead of vacuum drying to give amorphous valsartan.  
       EXAMPLE 5  
       [0015]     Valsartan (10 gm) is dissolved in isopropyl alcohol (70 ml). The solution is subjected to vacuum drying at about 45° C. for 15 hours to give 9.9 gm of amorphous valsartan.