Comparative Efficacy of Salbutamol and Salmeterol in Exercise-Induced Asthma

This study compared the protection provided by salbutamol and salmeterol against exercise-induced asthma. Asthmatic patients (n = 12) with exercise-induced asthma were exercised submaximally for 6 min on a treadmill 1, 6 and 12 h after inhalation of 200 μg salbutamol or 50 μg salmeterol. Each patient also took baseline exercise 1 h after two puffs of placebo. Two days later the drugs were administered in a double-blind trial of crossover design with an interval of 48 h between the two treatments. The main parameters measured were: air flow with a Wright flowmeter and mediator concentrations (histamine, leucotriene and prostaglandin D₂ measured by radioimmunoassay) in venous blood, which was withdrawn before and 4 min after each exercise period. The maximum percentage bronchoconstriction recorded following placebo was 29 ± 4% and following salbutamol inhalation it was 4 ± 4%, 20 ± 13%, 27 ± 10%, respectively, for the exercise periods performed 1, 6 and 12 h after inhalation of the drug. Following salmeterol, the corresponding figures were 3 ± 4%, 3 ± 3% and 11 ± 9%. The concentrations of mediator in plasma were significantly increased after exercise. Salbutamol and salmeterol intake reduced these concentrations both when the patients were at rest and following the exercise period. This effect of both drugs on the mediators corresponded with the protection they provided against exercise-induced asthma and was maintained for 12 h after salmeterol inhalation and for 6 h after salbutamol inhalation.