Inhibition of passive lung anaphylaxis in the rat by AY-25,674.

The antiallergic properties of AY-25,674 were studied in a model of passive lung anaphylaxis. AY-25,674 caused a dose-related inhibition of antigen-induced bronchoconstriction in the passively sensitized rat. AY-25,674 was found to be twice as potent as disodium cromoglycate (DSCG) when injected intravenously. The oral administration of AY-25,674 also effectively inhibited antigen-induced bronchoconstriction. A tachyphylactic effect of repeated administration was found when the rats were pretreated with a large dose of AY-25,674. The compound did not significantly antagonize the bronchoconstriction produced by 5-hydroxytryptamine. These results indicate that AY-25,674 is an orally effective antianaphylactic compound with a mode of action similar to that of DSCG in preventing allergic mediator release.