Comparative effects of pirbuterol acetate, metaproterenol, and placebo aerosols on pulmonary function and incidence of cardiac ectopy.

This single-center, double-blind, randomized study compared the efficacy and safety of single-dose pirbuterol aerosol (0.2 mg and 0.4 mg) with metaproterenol (1.3 mg) and placebo aerosols. Twenty-four patients with asthma or chronic obstructive pulmonary disease (COPD) completed this crossover design study. Statistically significant improvement over placebo (p less than 0.05 to p less than 0.001) was noted for pirbuterol 0.2 mg and 0.4 mg in FEV1 (forced expiratory volume in 1 second) duration, peak, and area under the curve (AUC) responses, and in maximum midexpiratory flow rate (MMEF) peak and AUC responses. Pirbuterol at both the 0.2 mg and 0.4 mg doses demonstrated statistically significant improvements in pulmonary function tests and clinical assessment over metaproterenol 1.3 mg. Both drugs were well-tolerated and neither drug increased cardiac ectopy, as measured on 5-h Holter monitor tapes.