BRONCHODILATOR AND BRONCHOPROTECTIVE EFFECTS OF SALMETEROL IN YOUNG-PATIENTS WITH ASTHMA

Background: In adults with asthma, the selective beta2-adrenergic agonist salmeterol has a prolonged bronchodilator and bronchoprotective effect. To date, there are few published studies of salmeterol in children. Methods: We compared the bronchodilator and bronchoprotective effects of salmeterol, 25 and 50 mug, with salbutamol, 200 mug, and with placebo, administered via metered-dose inhaler, in a randomized, double-blind, within-patient, four-way crossover, single-dose study in 20 children. Results: Mean baseline forced expiratory volume in 1 second (FEV1) and PC20 methacholine were not significantly different (p > 0.05) on the 4 study days, and did not change significantly after placebo. FEV, increased significantly from 5 to 30 minutes after salbutamol, and from 5 minutes to 12 hours after 25 mug or 50 mug salmeterol, compared with placebo. After 25 mug or 50 mug salmeterol, FEV1 was significantly lower than after salbutamol at 5 and 10 minutes, did not differ from salbutamol at 30 minutes, and was significantly greater than after salbutamol from 3 to 12 hours. No significant difference occurred between the effect of 25 mug salmeterol and the effect of 50 mug salmeterol on FEV1. After salbutamol, there was a significant increase in PC20 only at 30 minutes. After 25 mug or 50 mug salmeterol, PC20 increased significantly from 30 minutes to 12 hours. Salmeterol, 25 mug and 50 mug provided significantly greater bronchoprotection than salburamol from 3 to 12 hours and from 30 minutes to 12 hours, respectively. Salmeterol, 50 mug, provided significantly better bronchoprotection than 25 mug salmeterol from 30 minutes to 12 hours. The amount of change in PC20 accounted for by change in FEV1 varied from 14% to 28%, indicating that protection against bronchoconstriction was not entirely dependent on bronchodilation. Conclusions: Salmeterol is a potent, long-acting bronchodilator, with a slower onset Of bronchodilation than salbutamol. It provides significantly greater and longer-lasting protection against bronchoconstriction than salbutamol.