The effect of a 100 mg pirenzepine--treatment on acid secretion and serum gastrin.

50 mg pirenzepine inhibit basal acid secretion by 39.9% and peptone-stimulated acid output by 21.3%. The percentage of inhibition is nearly doubled if the same dose is given after a treatment with 50 mg pirenzepine twice daily for 3 to 7 days. No acute effect on serum gastrin levels can be demonstrated by a single dose of pirenzepine. After pretreatment only a small increase of basal gastrin levels is observed, serum gastrin does not change during stimulation. On the bases of these results the effect on ulcer healing by high doses of pirenzepine is probably due to a much more pronounced acid inhibition. One reason for stronger inhibition of acid secretion after pretreatment with pirenzepine is probably accumulation of the drug, other reasons may be distribution space or receptor binding. The effect of anticholinergic drugs on serum gastrin concentrations is probably dose-dependent.