Salmeterol, a new long acting β 2 agonist, produces bronchodilatation for at least 12 hours in patients with asthma and when given in doses of 50 g twice daily provides more effective control of asthma symptoms than salbutamol 200 g four times daily.

The dose equivalence of salmeterol compared with salbutamol determined from single dose studies of acute changes in lung function has ranged from 1 to 16 - that is, doses of salmeterol from 12.5 g to 200 g have produced similar bronchodilatation as 200 g salbutamol.