Inhibition of gastric acid secretion by selective and nonselective anticholinergics.

Anticholinergics have been used for many years to reduce gastric acid secretion (e.g., in peptic ulcer patients). Because of their side effects and the advent of histamine-2 receptor antagonists, however, anticholinergics are now used much less frequently as antisecretory agents. Recently, a selective antimuscarinic type of anticholinergic, pirenzepine, has been developed. This agent reduces acid secretion and heals ulcers without producing serious side effects, probably by preferentially blocking a certain subtype of muscarinic receptor for acetylcholine (M1 receptor). This article will review the current types and subtypes of cholinergic receptors and the mechanisms by which antimuscarinic agents, including pirenzepine, reduce gastric acid secretion.