Omeprazole inhibition of nocturnal gastric secretion in patients with duodenal ulcer.

We studied the effect of single 08.00 h doses of omeprazole or placebo on gastric acid secretion during the following night, 14 to 23 h after administration, in seven male subjects with duodenal ulcer. The drug was given orally, double-blind, in randomized order. Omeprazole 20 mg, 40 mg and 80 mg reduced mean total overnight acid output by 43%, 73% and 91% respectively and median pH increased from 1.4 with placebo to 1.6, 3.1 and 7.0 respectively. The inhibitory effect was maintained throughout the study period. No clinical side effects or abnormalities of laboratory screening tests were seen. Omeprazole is well tolerated and administration at 08.00 h produces prolonged dose related inhibition of acid output during the following night.