DOUBLE-BLIND, CLINICAL EFFICACY STUDY COMPARING 400 MU-G OF PIRBUTEROL VERSUS PLACEBO DELIVERED BY A BREATH-ACTUATED AEROSOL INHALER

Pirbuterol is a selective beta-2 adrenergic agonist that is indicated for the treatment of bronchospasm in patients with asthma. Traditional ly, the most common form of administration of the beta-2 agonist is by inhalation from a pressurized metered-dose inhaler. The purpose of th is study was to compare the bronchodilator efficacy and safety of two inhalations (400 mu g) of pirbuterol delivered by a breath-actuated ae rosol (BAA) with that of two inhalations of a matching placebo. Patien ts were studied on each of two study days with a baseline electrocardi ogram and sequential pulmonary function testing for 6 hr. Fourteen pat ients completed the study. The mean age was 32 years, with a range of 21-56 years. Most of these individuals had had asthma for more than 5 years. The mean percent increase in FEV(1) was 41.2% for pirbuterol co mpared to 25.4% for placebo (p = 0.0038). The duration of improvement of >15% over baseline was 4.5 hr for the pirbuterol group compared to 1.8 hr for the placebo group (p = 0.0022). There was no difference bet ween the groups with respect to onset of action or time to reach peak effect. There was no significant difference between treatments with re spect to any cardiovascular parameter. We conclude that pirbuterol in the BAA device produced significantly more bronchodilatation than did placebo with respect to its peak effect, duration of effect, and perce ntage change from baseline. Therefore, we feel that pirbuterol adminis tered through the BAA device is a safe, effective means of treating bo th acute and chronic asthma.