Clinical comparison of cimetidine and ranitidine.

Ranitidine is a histamine H2-receptor antagonist that differs structurally from cimetidine. We assessed its kinetics, potency, and duration of effect in patients with chronic duodenal ulcers. Ranitidine had an absorption lag time of approximately 30 min, an absorption half-life (t 1/2) of approximately 40 min, and an elimination t 1/2 of 3 hr, all differing from those of cimetidine. It is five times as potent, so that equal doses of ranitidine induce considerably longer suppression of both basal and food-stimulated gastric acid secretion than cimetidine.