Chemical and biologic characteristics of roxatidine acetate.

Roxatidine acetate is a specific and competitive H2-receptor antagonist, as shown in isolated rabbit gastric glands or guinea pig atria preparations. The antisecretory effect of roxatidine acetate is mediated by its main metabolite, roxatidine. In the rat, roxatidine acetate was equipotent after intraduodenal and intraperitoneal administration, indicating excellent bioavailability. Roxatidine acetate and roxatidine were equipotent in the rat after intravenous administration. In the Heidenhain-pouch dog stimulated by food ingestion or maximal histamine dosing, roxatidine acetate and roxatidine proved to be 3-6 times more potent than cimetidine in inhibiting gastric acid secretion. From in vitro experiments it can be concluded that roxatidine acetate and ranitidine are equipotent. Roxatidine acetate has no antiandrogenic effects and does not influence drug-metabolizing enzymes in the liver.