EFFECT OF IPRATROPIUM BROMIDE AND OR SODIUM CROMOGLYCATE PRETREATMENTON WATER-INDUCED BRONCHOCONSTRICTION IN ASTHMA/

The mechanisms underlying water-induced bronchoconstriction are still not fully understood. Cholinergic reflexes and mast cell mediator rele ase are currently believed to play an important pathogenetic role. In order to evaluate the relative contribution of each of these mechanism s, we studied the effect of ipratropium bromide (80 mu g), a muscarini c antagonist, and sodium cromoglycate (20 mg), an inhibitor of mast ce ll mediator release, administered alone and in combination, in the pre vention of bronchospasm induced by ultrasonic mist of distilled water (UMDW). Fifteen patients with documented atopic asthma sodium cromogly cate ultrasonic mist of distilled water and hyperresponsiveness to dis tilled water were selected for this randomized, placebo-controlled, do uble-blind study, Airway responses to pharmachological agents and bron chial challenge were measured by change in specific airways conductanc e (sGaw). Sodium cromoglycate had no effect on bronchial calibre, whil st ipratropium bromide and the combination of the two drugs produced a significant bronchodilation 30, 60 and 90 min after treatments. The m aximal increase in sGaw (mean %+/-SD) was observed at 90 min: 63+/-28% and 58+/-22% after ipratropium bromide and the combined drugs respect ively, UMDW (2, 4, 8, 16 mi water) caused a -36+/-19%, -42+/-19%, -49/-18%,-56+/-15% mean %+/-SD fall in sGaw after placebo. Pretreatment w ith sodium cromoglycate abolished the bronchoconstriction to 2 ml (fal l sGaw -5+/-23% Ns) and significantly reduced the effect of 4(-15+/-22 %), 8 (-21+/-20%) and 16 mi (-24+/-18%) water, Ipratropium bromide cau sed a weaker but significant attenuation; fall in sGaw was -15+/-15%, -18+/-19%, 30+/-21% and -41+/-27% with 2, 4, 8 and 16 ml water respect ively, Treatment with both drugs prevented UMDW bronchoconstriction; a decrease in sGaw greater than 10% was observed in four subjects only. These results suggest that water-induced bronchoconstriction is deter mined by more than one mechanism.