THE DURATION OF ACTION OF INHALED FORMOTEROL DRY POWDER

The duration of action of formoterol inhaled as a dry powder formulati on is compared with placebo and a reference treatment of salbutamol dr y powder in patients with bronchial asthma. This single-centre, double -blind, cross-over study recruited 23 outpatients with clinically stab le asthma. These patients were treated with 12 mu g formoterol, 400 mu g salbutamol or placebo in a randomly allocated sequence, with at lea st 2 days between treatments. Forced expiratory volume in Is of expira tion (FEV(1)) was measured at specified time points from 15 min to 15 hours post-treatment. Formoterol produced significantly higher values of FEV(1) at the primary endpoint of 12 hours compared with placebo an d salbutamol. No differences between FEV(1) values were seen for the a ctive treatments of formoterol and salbutamol for the first 5 hours po st-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 400 mu g salbutamol inhaled as a d ry powder. The duration of action of formoterol of at least 12 hours s een in this study is at least as long as that reported following admin istration from a metered dose inhaler (MDI) at the same dose level. Th e study also demonstrates that 12 mu g formoterol dry powder is well t olerated by patients.