Gastric antisecretory activity of telenzepine, a new M1-selective muscarinic antagonist: comparison with pirenzepine.

The new M1-receptor antagonist telenzepine has been studied for its antisecretory effect in different in vitro and in vivo experimental models in comparison with pirenzepine. Telenzepine was found to be from 3 to 10 times more potent than pirenzepine in inhibiting bethanechol-, pentagastrin- and dimaprit-induced acid secretion in the conscious gastric fistula cat. Also, in the lumen-perfused stomach of the anaesthetized rat, telenzepine was more active than pirenzepine as an inhibitor of bethanechol-induced acid secretion; the inhibitory effect of telenzepine lasted more than 3 hr, while that of pirenzepine disappeared within 1 hr. In the isolated gastric fundus from immature rats, telenzepine and pirenzepine did not modify the spontaneous acid secretion, whereas both drugs caused a competitive inhibition of bethanechol-induced acid secretion (pA2 values were 7.96 and 6.81 for telenzepine and pirenzepine, respectively). These data indicate that telenzepine is a potent antisecretory agent both in vitro and in vivo.