<chemical> N-(3-(1h-imidazol-4-yl)propyl)-n'-(2-(((5-methyl-1h-imidazol-4-yl)methyl)thio)ethyl)guanidine. A highly potent and specific histamine h2 receptor agonist. It has been used diagnostically as a gastric secretion indicator. ... Pharmacological action: histamine agonist. ... Chemical name: Guanidine, N-(3-(1H-imidazol-4-yl)propyl)-N'-(...