Effect of one-month treatment with cimetidine on gastric secretion and serum gastrin and pepsinogen levels.

The inhibitory effects of cimetidine on gastric acid and pepsin secretion were studied before and after 1 month of treatment with 300 mg of cimetidine four times a day in 15 male duodenal ulcer patients. Cimetidine inhibited both pentagastrin- and peptone meal-stimulated acid secretion significantly better before, than after, 1 month of treatment. Similarly cimetidine inhibited pentagastrin-stimulated pepsin secretion significantly better before treatment. Meal-stimulated serum gastrin concentrations were significantly higher after treatment. The mechanism(s) of these effects was not apparent.