Effect of prolonged cimetidine therapy on gastric acid secretion in man

In a double blind trial, 23 patients with endoscopically confirmed duodenal ulceration received cimetidine (300 mg four times daily in six patients, or 400 mg four times daily in 10 patients) or placebo (seven patients) for six weeks. Before entry into the trial, pentagastrin (6 microgram.kg-1.h-1)--stimulated gastric acid secretion after a single oral dose of 300 or 400 mg cimetidine was lowered by 82.1% and 81.0%, respectively, while no significant inhibition was recorded in the patients receiving placebo (8.8%). The same test repeated after six weeks of continuous treatment showed that the effect of the drug was maintained, the percentage inhibition of acid secretion being of the same order as in the first test.