Double-blind, clinical efficacy study comparing 400 micrograms 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. Traditionally, the most common form of administration of the beta-2 agonist is by inhalation from a pressurized metered-dose inhaler. The purpose of this study was to compare the bronchodilator efficacy and safety of two inhalations (400 micrograms) of pirbuterol delivered by a breath-actuated aerosol (BAA) with that of two inhalations of a matching placebo. Patients were studied on each of two study days with a baseline electrocardiogram and sequential pulmonary function testing for 6 hr. Fourteen patients 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 FEV1 was 41.2% for pirbuterol compared 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 between the groups with respect to onset of action or time to reach peak effect. There was no significant difference between treatments with respect 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 percentage change from baseline. Therefore, we feel that pirbuterol administered through the BAA device is a safe, effective means of treating both acute and chronic asthma.