Pirenzepine selectively inhibits gastric acid secretion: a comparative pharmacological study between pirenzepine and seven other antiacetylcholine drugs.

Intravenous doses of eight antiacetylcholine drugs reduced gastric acid secretion in the rat and caused pupil dilatation in the mouse. Inhibition by these drugs of oxotremorine-induced hypothermia in mice was also assessed. The ratio, ED50 (pupil dilatation)/ED50 (gastric acid inhibition), was greater (more favourable) for pirenzepine and oxyphencyclimine than for atropine, benzhexol, glycopyrronium, isopropamide, poldine or propantheline. However, oxyphencyclimine antagonised central oxotremorine activity at all doses having more gastric inhibitory activity. Pirenzepine is a peripheral antiacetylcholine drug more selective for reducing gastric acid secretion than for increasing pupil diameter and with little central antiacetylcholine effect.