Method for preparing a crystalline polymorph of terazosin monohydrochloride

摘要

A crystalline polymorphous terazosine monohydrochloride is obtained by suspending and treating a crystalline addition product of terazosine hydrochloride and methanol in a polar solvent which is an alcohol with 2 to 6 carbon atoms or a ketone with 2 to 6 carbon atoms or a mixture thereof. The thus obtained crystalline polymorphous terazosine hydrochloride is characterized by a reduced hygroscopicity and solvent residue retention capacity.