302 METHACHOLINE DOSE-RESPONSE CURVES BEFORE AND DURIN TREATMENT WITH SALMETEROL IN MILD ASTHMATIC CHILDREN

The long-term effects of long-acting beta-2-agonists on the airway sensitivity and maximal bronchoconstriction in asthmatic children have not been evaluated. We compared the effect of salmeterol 50 μg and salbutamol 200 μg bid. in 30 mild asthmatic children in a double-blind parallel study. None of the children were on inhaled corticosteroids. Methacholine dose-response curves were made up to a fall in FEV, of 45% or a maximal plateau bronchoconstriction was reached, before and during 4 months of treatment. PD20, was always measured 12h after the last medication gift. PD20 improved significantly only during salmeterol treatment: 0.7 doubling dose in the salmeterol group, −0.5 doubling dose in the salbutamol group (p<0.001). Maximal plateau bronchoconstriction was rarely seen, either before or during; treatment. We conclude that salmeterol during long-term treatment improves airway sensitivity, but we could not demonstrate a maximal response plateau.