Methods for the preparation of polymorphs of doxazosin mesylate

Abstract

Methods for the preparation of polymorphic forms of doxazosin mesylate are provided.

What is claimed is:  
     
         1 . A method for the preparation of Form A of doxazosin mesylate which comprises: 
 (a) dissolving doxazosin base and methanesulfonic acid in a solvent selected from the group consisting of an alcohol having from 1 to 8 carbon atoms; or a halohydrocarbon selected from the group consisting of dichloromethane, chloroform and trichloroethane; or mixtures thereof;    (b) precipitating Form A doxazosin mesylate from the resulting solution; and    (c) separating the Form A doxazosin mesylate product.    
     
     
         2 . A method for converting Form D doxazosin mesylate to Form A doxazosin mesylate which comprises: 
 (a) dissolving Form D and a solvent mixture of an alcohol having from 1 to 8 carbon atoms and a halohydrocarbon selected from the group consisting of chloroform, dichloromethane, 1,2-dichloroethane and trichloroethane,    (b) precipitating the Form A from the resulting solution; and    (c) separating the Form A doxazosin mesylate product.    
     
     
         3 . A method for the preparation of Form A of doxazosin mesylate which comprises: 
 (a) dissolving doxazosin base and methane sulfonic acid in methanol;    (b) precipitating Form A doxazosin mesylate from the resulting solution; and    (c) separating Form A doxazosin mesylate product.    
     
     
         4 . A method for the preparation of Form D of doxazosin mesylate which comprises: 
 (a) dissolving doxazosin base and methane sulfonic acid in an alcohol having from 1 to 8 carbon atoms;    (b) precipitating Form D doxazosin mesylate from the resulting solution; and    (c) separating the Form D doxazosin mesylate product.    
     
     
         5 . Form D doxazosin mesylate characterized by X ray diffraction (2θ) values 5.7, 17.1, 17.8, 18.4, 20.8, 24.3, 26.6.