Oral pirenzepine does not affect esophageal pressures in man

Pirenzepine has been proposed to selectively inhibit gastric acid production. In contrast to classical anticholinergics, pirenzepine does not appear to produce systemic side effects or to strongly inhibit contractions in gastrointestinal tract smooth muscle. This study compares the effects of two doses of pirenzepine (25 and 50 mg per os) with a standard anticholinergic, propantheline, 30 mg per os, and with placebo on esophageal contraction pressures in 12 healthy volunteers in a random double-blind study sequence. No significant change in lower esophageal sphincter pressure (LESP) or in peristaltic pressures occurred with placebo or pirenzepine 25 or 50 mg. However, propantheline produced marked reduction in peristaltic contraction pressures and increased velocity (4 of 12 subjects had complete loss of peristalsis). LESP decrease was almost significant. Seven of 12 subjects experienced dry mouth after propantheline, but none after either dose of pirenzepine or placebo. This study indicates that, as opposed to a classical anticholinergic, pirenzepine does not adversely affect esophageal contraction pressures nor does it have anticholinergic side effects with the oral doses studied.