Effect of cimetidine on pentagastrin-stimulated gastric acid and pepsin secretion before and after 6 weeks of cimetidine treatment.

To see whether the effect of cimetidine changes during a treatment period, the effect of intravenous cimetidine on pentagastrin-stimulated gastric acid and pepsin secretion was studied before and after a 6-week course of oral cimetidine treatment, 1 g/day, in 10 duodenal ulcer patients. Pentagastrin, 1.5 microgram . kg-1 . h-1, was infused for 165 min, and cimetidine, 1.2 mg . kg-1 . h-1, was added by concomitant infusion during the last 90 min. The second secretion test was carried out 60 hours after the last dose of cimetidine. Acid and pepsin secretion, in response to pentagastrin stimulation, was not significantly changed after 6 weeks of daily cimetidine treatment. The response to pentagastrin plus cimetidine was, however, significantly higher at the end than at the start of the treatment period. The results suggested a slightly reduced effect of cimetidine after prolonged use.