THE DURATION OF ACTION OF INHALED FORMOTEROL DRY POWDER

SUMMARY The duration of action of formoterol inhaled as a dry powder formulation is compared with placebo and a reference treatment of salbutamol dry powder in patients with bronchial asthma. This single-centre, double-blind, cross-over study recruited 23 outpatients with clinically stable asthma. These patients were treated with 12μg formoterol, 400μg salbutamol or placebo in a randomly allocated sequence, with at least 2 days between treatments. Forced expiratory volume in 1s of expiration (FEV₁) was measured at specified time points from 15 min to 15 hours post-treatment. Formoterol produced significantly higher values of FEV₁ at the primary endpoint of 12 hours compared with placebo and salbutamol. No differences between FEV₁ values were seen for the active treatments of formoterol and salbutamol for the first 5 hours post-inhalation. Formoterol was significantly superior to placebo at all time points, whereas salbutamol was significantly superior to placebo for the first 5 hours.This study demonstrates that formoterol, when given as a dry powder inhalation, has a significantly longer duration of acute bronchodilator action than 400μg salbutamol inhaled as a dry powder. The duration of action of formoterol of at least 12 hours seen in this study is at least as long as that reported following administration from a metered dose inhaler (MDI) at the same dose level. The study also demonstrates that 12μg formoterol dry powder is well tolerated by patients.