crystalline polymorphic forms of fexofenadine

Abstract

The present invention is related to a novel polymorph of Fexofenadine and processes of preparation thereof.

1 . A crystalline Form A of Fexofenadine which is characterized by the following X-ray powder diffraction pattern (d values in A°): 23.11, 11.50, 8.29, 7.03, 6.67, 6.16, 6.02, 5.75, 5.43, 5.33, 5.07, 4.69, 4.63, 4.44, 4.20, 4.15, 4.07, 3.55, and 3.44. 
   
   
       2 . The crystalline Form A of Fexofenadine according to  claim 1 , characterized by the following infrared absorption peaks (in cm −1 ) FT-IR (In KBr): 3421, 3058, 2936, 2366, 2343, 1571, 1509, 1490, 1447, 1390, 1334, 1167, 1097, 1073, 1018, 960, 916, 849, 745, 706, 666, 637, 617, 541. 
   
   
       3 . The crystalline Form A of Fexofenadine according to  claim 1 , characterized by a melt endotherm with a peak temperature at about 227-231° C. 
   
   
       4 . A process for preparing Form A of Fexofenadine according to  claim 1  which comprises:
 a. recrystallizing crude Fexofenadine in a (C 1 -C 3 ) alkanol;   b. azeotropically refluxing Fexofenadine in a non polar organic solvent, an organic solvent or a mixture thereof for 15 minutes to 6 hours;   c. stirring the reaction mixture at ambient temperature for 30 minutes to 2 hours; and   d. isolating the Form A of Fexofenadine.   
   
   
       5 . A pure Form A of Fexofenadine according to  claim 1 , wherein the purity of Form A is greater than 99.5%. 
   
   
       6 - 11 . (canceled) 
   
   
       12 . The process as claimed in  claim 4 , wherein the non polar organic solvent is selected from toluene or xylene. 
   
   
       13 . The process as claimed in  claim 4 , wherein the (C 1 -C 3 ) alkanol is methanol, ethanol or propanol. 
   
   
       14 . The process as claimed in  claim 4 , wherein the nonpolar organic solvent is a (C 6 -C 9 ) alkyl. 
   
   
       15 . The process as claimed in  claim 4 , wherein the nonpolar organic solvent is n-hexane, hexane, octane, nonane or cyclohexane. 
   
   
       16 . The process as claimed in  claim 4 , wherein the organic solvent is selected from (C 1 -C 4 ) alkyl acetates. 
   
   
       17 . The process according to  claim 4 , wherein the organic solvent is ethyl acetate. 
   
   
       18 - 19 . (canceled) 
   
   
       20 . The crystalline Form A of Fexofenadine according to  claim 2 , characterized by a melt endotherm with a peak temperature at about 227-231° C. 
   
   
       21 . Form A of fexofenadine according to  claim 2 , having a purity of Form A greater than 99.5%. 
   
   
       22 . Form A of fexofenadine according to  claim 3 , having a purity of Form A greater than 99.5%. 
   
   
       23 . Crystalline Form A of fexofenadine, having an X-ray powder diffraction pattern with peak locations substantially in accordance with  FIG. 1 . 
   
   
       24 . A process for preparing a crystalline polymorphic form of fexofenadine, comprising azeotropically refluxing fexofenadine in a non polar organic solvent, a (C 1 -C 4 ) alkyl acetate, or a mixture thereof. 
   
   
       25 . The process of  claim 24 , wherein a crystalline polymorphic form of fexofenadine is Form A, having an X-ray powder diffraction pattern with peak locations substantially in accordance with  FIG. 1 . 
   
   
       26 . The process of  claim 24 , wherein a non polar solvent is toluene, xylene, or a (C 6 -C 9 ) alkyl. 
   
   
       27 . The process of  claim 24 , wherein azeotropically refluxing is conducted in a mixture of a non polar organic solvent and a (C 1 -C 4 ) alkyl acetate.