[Bronchodilator effect of salmeterol and inhibition of bronchial hyperreactivity]

Salmeterol is a new long acting bronchodilator which is specific for beta-2 adrenergic receptors. Its bronchodilator effects can persist for at least 12 hours after inhalation. This drug can inhibit the bronchoconstrictor effects of methacholine up to 12 hours after inhalation and this effect is proportional to the administered dose. Salmeterol improves daily expiratory flow rates and blocks exercise-induced bronchoconstriction. A 50 micrograms dose, inhaled before an antigenic bronchoprovocation, can markedly reduce for up to 24 hours the immediate and late bronchospastic responses to antigen. Moreover, salmeterol inhibits the increase in bronchial responsiveness induced by antigenic exposure. This latter effect does not seem to be related to a persisting bronchodilatation. The responsible mechanisms for this inhibition of allergic response or if its effects are only due to a functional antagonism remain to be explored. A particularly relevant point would be to determine of salmeterol diminishes or blocks the inflammatory bronchial asthmatic reaction.