Carmoterol is a long-acting β2-adrenoceptor agonist with a rapid onset of action and potent bronchodilating activity. Carmoterol has a similar onset of action compared to salbutamol and formoterol, and a faster onset of action compared to salmeterol. Furthermore, the duration of tracheal smooth muscle relaxation is longer for carmoterol compared to both formoterol and salmeterol. In asthmatic patients, the PK of carmoterol is proportional to the dose, and nonlinear accumulation of the drug after repeated dosing treatments is negligible. In patients with persistent asthma carmoterol 2 µg administered once daily is as effective as formoterol 12 µg twice daily. Safety and tolerability results are similar between carmoterol and formoterol. There were no significant changes in ECG results, blood pressure or serum potassium or glucose levels