Cimetidine A used as histamine H-2 receptor blocker - is a crystallographically pure polymorphic form of N-methyl-(N')-cyano-(N'')-methyl-imidazolyl methylthio-ethyl-guanidine

摘要

A practically crystallographically pure polymorphic form of cimetidin N-methyl-N'-cyano-N"-(2-((5-methyl-4-imidazolyl)-methylthio)ethy- l)guanidine , (as cimetidin A). (I), has an infrared spectrum (1% on KBr disc) having broad, pronounced (high) peaks at 1400 and 1395cm-1, a narrow pronounced peak at 1205 cm-1 and a narrow peak of av. height at 1155cm-1 and no peak at 1180 cm-1. Practically crystallographically pure indicates that (I) contains 5(3)%, of any other polymorphic form. (I) is administered in unit doses of 50-750mg (pref. 200-600mg), 1-6 times daily to give a pref. daily dosage of 500-1500mg. (I) is usually administered orally but may also be given parenterally or topically.