Drying process for preparing crystalline solid famciclovir

Abstract

The present invention provides a drying process for preparing crystalline solid famciclovir form I comprising the steps of: i) preparing a wet crystalline form of famciclovir; ii) drying the wet crystalline form of famciclovir at a temperature of below 50° C. until the crystalline form contains less than 15% (wt/wt) wetness; and iii) drying the wet crystalline form of famciclovir at a temperature of above 50° C. until the wet crystalline form of famciclovir contains less than 0.05% (wt/wt) water to obtain crystalline solid famciclovir form I.

1 . Crystalline famciclovir containing less than about 1% (wt/wt) solvent. 
   
   
       2 . The crystalline famciclovir of  claim 1  containing less than about 0.5% (wt/wt) solvent. 
   
   
       3 . The crystalline famciclovir of  claim 2  containing less than about 0.05% (wt/wt) solvent. 
   
   
       4 . The crystalline form of  claim 3 , wherein the crystalline form is famciclovir Form I. 
   
   
       5 . Crystalline famciclovir containing less than about 1% (wt/wt) solvent prepared by a process comprising:
 a) providing a wet crystalline form of famciclovir containing about 40% (wt/wt) or less solvent;   b) drying the wet crystalline form of famciclovir of step a) at a temperature of from about 30° C. to about 50° C. to obtain a wet crystalline form of famciclovir; and   c) drying the wet crystalline form obtained from step b) at a temperature higher than 50° C. to obtain the crystalline form of famciclovir containing less than about 1% (wt/wt) solvent.   
   
   
       6 . Crystalline famciclovir containing less than about 0.5% (wt/wt) solvent prepared by a process comprising:
 a) providing a wet crystalline form of famciclovir containing about 40% (wt/wt) or less solvent;   b) drying the wet crystalline form of famciclovir of step a) at a temperature of from about 30° C. to about 50° C. to obtain a wet crystalline form of famciclovir;   c) drying the wet crystalline form obtained from step b) at a temperature higher than 50° C. to obtain a crystalline form of famciclovir containing less than about 1% (wt/wt) solvent; and   d) drying the crystalline form of famciclovir obtained in step c) at a temperature ranging from higher than about 50° C. to about 80° C. to obtain the crystalline form of famciclovir containing less than about 0.5% (wt/wt) solvent.   
   
   
       7 . Crystalline famciclovir containing less than about 0.05% (wt/wt) solvent prepared by a process comprising:
 a) providing a wet crystalline form of famciclovir containing about 40% (wt/wt) or less solvent;   b) drying the wet crystalline form of famciclovir of step a) at a temperature of from about 30° C. to about 50° C. to obtain a wet crystalline form of famciclovir;   c) drying the wet crystalline form obtained from step b) at a temperature higher than 50° C. to obtain a crystalline form of famciclovir containing less than about 1% (wt/wt) solvent; and   d) drying the crystalline form of famciclovir obtained in step c) at a temperature ranging from higher than about 50° C. to about 80° C. to obtain the crystalline form of famciclovir containing less than about 0.05% (wt/wt) solvent.   
   
   
       8 . The crystalline form of  claim 7 , wherein the solvent is water and the crystalline form is famciclovir Form I.