Effect of bedtime ranitidine on overnight gastric acid output and intragastric pH: dose/response study and comparison with cimetidine.

A dose/response study has been carried out in seven patients with endoscopically proven duodenal ulcers in symptomatic remission, measuring intragastric pH and gastric acid output overnight after a bedtime dose of ranitidine (75 mg, 150 mg, and 300 mg); and the results have been compared with placebo and with bedtime cimetidine 400 mg. The currently recommended ranitidine maintenance dose (150 mg) was the optimum because it was significantly more effective than ranitidine 75 mg in terms of intragastric pH but not of acid output, and there was no difference from 300 mg in terms of either measurement. It was also significantly more effective than the currently recommended cimetidine maintenance dose (400 mg) in terms of inhibiting overnight acid output (92% vs 80% inhibition, p less than 0.05), and of maintaining intragastric pH above 5 (100% vs 17% of the overnight period, p less than 0.001).