Daytime acid secretion after a single dose of ranitidine and cimetidine--a double blind crossover study.

The purpose of the study was to evaluate the duration of inhibition of acid secretion by single oral doses of cimetidine and ranitidine. Basal and postprandial acid secretion in 6 healthy volunteers were measured for 14h by intermittent aspiration and prolonged intragastric titration. 400 mg cimetidine reduced daytime acid secretion by 22% and 150 mg ranitidine produced 38% inhibition. Although the elimination half lives of the drugs were similar, ranitidine led to more pronounced inhibition of acid secretion during the later part of the day. The longer duration of pronounced acid inhibition by ranitidine appears to be due solely to its greater potency.