Telenzepine is at least 25 times more potent than pirenzepine--a dose response and comparative secretory study in man.

Telenzepine is an analogue of pirenzepine with a higher potency and similar selectivity for M1-receptors in animals. In this placebo controlled, double blind, randomised study mean peptone stimulated gastric acid secretion (mean +/- SEM) of 10 male healthy subjects (58 +/- 6 mmol H+/3 h for placebo) was significantly and dose dependently inhibited by oral telenzepine (2 mg: 31 +/- 5, 3 mg: 23 +/- 5, 5 mg: 21 +/- 4 mmol H+/3 h). Telenzepine 3 and 5 mg were significantly stronger than pirenzepine 50 mg orally (37 +/- 8 mmol H+/3 h). Mean percentage acid inhibition was 37% for pirenzepine, and 48, 61, and 64% for 2, 3, and 5 mg telenzepine, respectively. Basal and peptone stimulated gastrin release was unaffected. Mean salivary output per three hours declined moderately from 156 +/- 45 g (placebo) to 136 +/- 45 g with pirenzepine and significantly to 88 +/- 28 g, 95 +/- 39 g and 39 +/- 13 g with telenzepine 2, 3, and 5 mg, respectively. There was a parallel effect on Na+, K+, Ca++ and amylase output in saliva. Near point vision was not altered by either drug. Pulse rates were lowered by both substances. Complaints of dry mouth were more frequent with telenzepine 5 mg. On a molar basis telenzepine proved to be a 25 and 50 times more potent inhibitor of gastric and salivary secretion, respectively.