Process for preparation of anhydrous azithromycin

Abstract

The present invention provides a stable form of azithromycin derivatives that act as antibiotics. These compounds are in anhydrous form and have increased stability over the hydrated forms.

1 - 20 . (canceled) 
   
   
       21 . A stable, pure anhydrous azithromycin having purity 96% w/w or more and having no detectable azithromycin hydrated forms when stored at 40±2° C. and at 75±5% relative humidity for a period of seven days. 
   
   
       22 . A stable, pure anhydrous azithromycin having purity 96% w/w or more and having no detectable azithromycin hydrated forms when stored at 25±2° C. and at 60±5% relative humidity for a period of seven days. 
   
   
       23 . The anhydrous azithromycin of  claim 21  or  22 , having X-Ray Powdered Diffraction pattern as shown in  FIG. 5 . 
   
   
       24 . The anhydrous azithromycin of  claim 21  or  22 , having Fourier Transform Infrared spectrum as shown in  FIG. 1 . 
   
   
       25 . The anhydrous azithromycin of  claim 21  or  22 , having Differential Scanning Calorimetric Thermogram as shown in  FIG. 3 . 
   
   
       26 . A pharmaceutical composition comprising the stable anhydrous azithromycin of  claim 21  or  22 . 
   
   
       27 . The pharmaceutical composition of  claim 26 , wherein the composition is administered by oral, parenteral, intravenous, intramuscular, topical or subcutaneous routes. 
   
   
       28 . A method to treast microbial infection in a mammal comprising administering an antimicrobially effective amount of the stable, pure anhydrous azithromycin of  claim 21  or  22  to a mammal in need thereof.