[Effects of flutropium bromide, a new antiasthma drug, on mediator release from mast cells and actions of mediators]

The effects of flutropium bromide (Ba598Br), a new antiasthma drug possessing the quarternary ammonium structure of atropine derivatives, on mediator release from mast cells and on actions of leukotriene (LT) D4 and serotonin were investigated. Flutropium bromide (3 and 10 mg/kg, i.v.) showed an inhibitory action on the 48 hr homologous PCA in guinea pigs. Atropine showed no inhibitory effect. Flutropium bromide also inhibited the release of histamine from isolated rat mast cells stimulated by antigen, although the inhibitory action was weaker than that of disodium cromoglycate. Atropine also had no inhibitory action in this case. Flutropium bromide and atropine showed no antagonistic action against LTD4-induced contraction of isolated tracheal smooth muscle of guinea pigs. Inhalation of flutropium bromide (0.3%) also showed no antagonistic action against serotonin-induced bronchoconstriction in dogs. From the above results, it is indicated that flutropium bromide has a weak mast cell stabilizing action, but no antagonistic action against LTD4 and serotonin.