Omeprazole, a long-lasting inhibitor of gastric secretion.

Omeprazole is a potent inhibitor of gastric acid secretion (GAS). It has a unique mechanism of action within the parietal cell where it inhibits (H+-K+) ATPase in secretory membranes. The inhibitory effect of omeprazole was measured over a 24-hr period in the dog. Seventy-five minutes after start of pentagastrin-stimulated GAS, placebo or omeprazole (0.5-3.0 micrograms/kg) iv was given to six dogs and GAS was collected for another 2 hr. Twenty-four hours later, GAS was again measured. Omeprazole produced a prompt and dose-dependent reduction of GAS, and significant suppression (44%) was still present at 24 hr.