Pharmacology and clinical efficacy of ranitidine, a new H2-receptor antagonist.

Ranitidine is a new histamine H2-receptor antagonist that includes a furan ring structure, whereas other H2-receptor antagonists include an imidazole ring. It is more potent than cimetidine in inhibiting gastric acid secretion and lacks cimetidine's anti-androgenic and hepatic microsomal enzyme inhibiting effects. In the recommended dosage of 150 mg twice daily, ranitidine is as effective as cimetidine in healing duodenal and gastric ulcers and has the advantages of less frequent dosing and fewer side effects. Ranitidine appears to be the drug of choice in the treatment of the Zollinger-Ellison syndrome because of its increased potency and lesser effect on endocrine function compared to cimetidine.