Two orthorhombic polymorphs of hydromorphone

Conditions to obtain two polymorphic forms by crystallization from solution were determined for the analgesic drug hydromorphone [C17H19NO3; systematic name: (4R,4aR,7aR,12bS)-9-hydroxy-3-methyl-1,2,4,4a,5,6,7a,13-octahydro-4,12-methanobenzofuro[3,2-e]isoquinolin-7-one]. These two crystalline forms, designated as I and II, belong to the P2(1)2(1)2(1) orthorhombic space group. In both polymorphs, the hydromorphone molecules adopt very similar conformations with some small differences observed only in the N-methyl amine part of the molecule. The crystal structures of both polymorphs feature chains of molecules connected by hydrogen bonds; however, in form I this interaction occurs between the hydroxyl group and the tertiary amine N atom whereas in form II the hydroxyl group acts as a donor of a hydrogen bond to the O atom from the cyclic ether part.