The Effect of Pirenzepine and L-Hyoscyamine on Gastric Emptying and Salivary Secretion in Healthy Volunteers

Abstract

Pirenzepine is used in the treatment of peptic ulcer disease as an inhibitor of gastric acid secretion. Recent studies suggest that the mode of action on the stomach may be selectively anticholinergic. The present study was undertaken to compare the effect of pirenzepine on gastric emptying with the effect of a widely used classical anticholinergic drug and of placebo. In a double-blind double-dummy study 9 healthy volunteers received 50 mg pirenzepine twice a day, 0.6 mg L-hyoscyamine twice a day or 2 placebo tablets twice a day for 4 days before the gastric emptying test. Gastric emptying of a liquid test meal was measured by the method of George. Maximum salivation capacity was registered by the method of Blum 2 and 4 h after the last dose was given. Gastric emptying was delayed during L-hyoscyamine; the emptying was slightly accelerated by pirenzepine when compared with placebo. The difference between L-hyoscyamine and pirenzepine was statistically significant for the time in which the volume fell to 75 and 50% (P < 0.01). The salivation was significantly more inhibited by L-hyoscyamine than by pirenzepine. Pirenzepine in doses inhibiting gastric acid secretion does not delay gastric emptying when compared with an equipotent dose of a classical anticholinergic drug, nor does it inhibit salivary secretion as much as L-hyoscyamine. Pirenzepine may indeed be a selective anticholinergic drug predominantly acting on gastric secretion.