[Pharmacological study of mequitazine (LM-209) (II). Anti-allergic action (author's transl)]

The anti-allergic effect of Mequitazine (LM-209) which was found to have an anti-histaminic activity was investigated in guinea-pigs. The inhibitory activities of LM-209 on the Schultz-Dale reaction and ileum contraction by some mediators released from the sensitized guinea-pig lung were the same as those of clemastine fumarate (CL) but with 5 times the potency. LM-209 and CL, but these activities were less potent than in the case of disodium cromoglycate. The various anaphylactic reactions mediated by IgG in guinea-pigs were inhibited by LM-209, CL and chlorpheniramine maleate (CPM). The homologous PCA mediated IgE in rats was also inhibited by LM-209, CL and CPM, but the duration of the action with LM-209 was markedly longer. In experimentally-induced asthma, the decrease of respiratory rate and volume was significantly inhibited by LM-209, but was not affected by CL. Thus, LM-209 seems to inhibit the allergic reaction mainly by an antagonistic action on allergic mediators.