Abstract

The effects of single doses of cimetidine 800, 1200, and 1600 mg, given at 2300 h or 800, and 1600 mg at 1800 h, have been studied in patients with duodenal ulcer disease in symptomatic remission, and compared with cimetidine 400 mg bd (0800 h and 2300 h) and ranitidine 300 mg (given at 1800 h) respectively. A dose related reduction in intragastric acidity was seen. All single nocturnal (2300 h) doses of cimetidine produced anacidity overnight. This was not achieved with dosing at 1800 h although the duration of inhibition of gastric acidity was longer. Inhibition of overnight acid and pepsin outputs were similarly dose and timing related, but inhibition of peptic activity was much less after dosing at 1800 h. Cimetidine 1600 mg and ranitidine 300 mg were similar in their effects.