Protection against allergen-induced asthma by salmeterol.

The effects of the long-acting beta 2-agonist salmeterol on early and late phase airways events provoked by inhaled allergen were assessed in a group of atopic asthmatic patients. In a placebo-controlled study, salmeterol 50 micrograms inhaled before allergen challenge ablated both the early and late phase of allergen-induced bronchoconstriction over a 34 h time period. Salmeterol also completely inhibited the allergen-induced rise in non-specific bronchial responsiveness over the same time period. These effects were shown to be unrelated to prolonged bronchodilatation or functional antagonism. These data suggest novel actions for topically active long-acting beta 2-agonists in asthma that extend beyond their protective action on airways smooth muscle.