Effect of omeprazole, a substituted benzimidazole, on 24-h intragastric acidity in patients with peptic ulcer disease.

Intragastric pH was measured during physiological conditions over 24-h periods in patients with peptic ulcer disease. After single oral doses of 20, 40, and 80 mg omeprazole we found a dose-dependent reduction in mean intragastric acidity ranging from 38% to 99%. After treatment for 1 week with omeprazole, 40 mg daily, with or without an initial loading dose of 80 mg, intragastric acidity was decreased by more than 99%. This is a more pronounced decrease in acidity than can be achieved even with very high doses of histamine H2-receptor antagonists.