Objective: This study compared the bronchodilator efficacy and safety of indacaterol with placebo, salbutamol and salmeterol, in patients with persistent asthma, at single therapeutic and supratherapeutic doses.Research design and methods: This was a randomised, open-label crossover study in adult subjects with asthma (forced expiratory volume in 1 second [FEV1] ≥ 60% predicted). In part A, patients (n = 20) received single doses of indacaterol 200 μg, salbutamol 200 μg, salmeterol 50 μg and placebo. In part B, patients (n = 19) received single doses of indacaterol 1000 μg, salbutamol 1000 μg, salmeterol 250 μg and placebo.Main outcomes measures; Results: For the primary endpoint, FEV1 area under the effect curve during 0–24 h, indacaterol 200 μ g was statistically superior to placebo and salbutamol. Indacaterol 200 μg FEV1 was higher than placebo (5 min to 24 h), salbutamol 200 μg (4–24 h), and salmeterol 50 μg (5 and 15 min and 22 and 24 h). Few adverse events were reported; all were mild or moderate in severity. Initial changes were observed in glucose, potassium, heart rate and QTc interval, but all values remained within normal ranges. Values matched placebo levels after a shorter time for indacaterol 1000 μg than for salmeterol 250 μg.Conclusions: In this single-dose, open-label study, indacaterol 200 μg provided effective 24-h bronchodilation, with a longer duration than salmeterol 50 μg and a good overall safety profile. The sustained bronchodilation of indacaterol 1000 μg was not associated with sustained systemic adverse effects. [ABSTRACT FROM AUTHOR]