Kinetic analysis of the interaction of mifentidine with gastric H2-receptors in the conscious dog.

The H2-receptor antagonists mifentidine and cimetidine were compared for their ability to antagonize the activation of H2-receptors in the conscious dog. Dose-response curves to dimaprit in stimulating gastric secretion were displaced to the right in a dose-related fashion by both drugs. Schild and Eadie-Hofstee analysis of these data indicated that mifentidine and cimetidine inhibited in vivo activation of H2-receptors in a manner compatible with competitive surmountable antagonism. Mifentidine displayed a 24fold greater potency than cimetidine as H2 antagonist in the conscious dog.