Effect of single and repeated doses of oral omeprazole on gastric acid and pepsin secretion and fasting serum gastrin and serum pepsinogen I levels.

Abstract

The effect of omeprazole on gastric acid and pepsin secretion and fasting serum gastrin and serum pepsinogen I levels was studied in 12 healthy volunteers. Omeprazole, 40 mg enteric-coated granules, or placebo was given once daily for nine days in a double-blind crossover study design. Twenty-four hours after a single dose of omeprazole, mean basal and mean pentagastrin-stimulated acid output decreased significantly. This effect was more pronounced after nine days of treatment. Basal pepsin output was significantly reduced only in those subjects with basal anacidity during omeprazole treatment. Stimulated pepsin output was slightly reduced after a single dose but unaltered after nine days of omeprazole. Fasting serum gastrin and serum pepsinogen I levels increased significantly during omeprazole treatment. It is concluded that omeprazole is a potent and selective inhibitor of gastric acid secretion, probably without a direct effect on pepsin secretion. However, in cases of basal anacidity during omeprazole administration, basal pepsin secretion is reduced. During omeprazole treatment, fasting serum levels of gastrin and pepsinogen I rise.