Salmeterol provides prolonged protection against exercise-induced bronchoconstriction in a majority of subjects with mild, stable asthma

In patients with asthma, exercise-induced symptoms are well recognized and frequently limiting. Currently available β 2-receptor agonists have a short duration of action and breakthrough symptoms may occur. We studied the efficacy of the recently developed long acting inhaled β 2-agonist salmeterol with respect to protection against exercise-induced bronchoconstriction. Twelve patients with mild to moderate, stable asthma were recruited (age range 21–33 years). They each underwent treadmill exercise tests, with target heart rate of approximately 90% of predicted maximu, 1, 6 and 12 h after a single dose of salmeterol 50 μg, salbutamol 200 μg and placebo. Patients breathed through a two-way valve, inspiring dry air from a compressed air cylinder via a Douglas bag to maintain constant humidity. The primary efficacy variable analysed was the maximum percentage fall in FEV 1 and FVC from pre-exercise readings within the first 30 min post-exercise. At 1 h post-dose there was significant protection in terms of fall in mean ± sem FEV 1 in response to exercise challenge after either salmeterol (0·83 ± 6·2%) or salbutamol (3·8 ± 5·5%) as compared with placebo (27·1 ± 7·3%). At 6 h post-dose, fall in FEV 1 on salmeterol was 11·3 ± 3·8% as compared with salbutamol, 28·0 ± 5·7% and placebo, 32·0 ± 7·0%. At 12 h post-dosing there was still significant protection in terms of fall in FEV 1 in the salmeterol treated group, 12·8 ± 4·9%, as compared with salbutamol, 28·7 ± 4·9% and placebo, 25·4 ± 7·3%. Similar results were found with respect to changes in FVC in these patients. We conclude that salmeterol is effective in protecting against exercise-induced bronchoconstriction in the majority of subjects with mild, stable asthma and that this effect lasts for at least 12 h.