The protective effect and duration of action of metaproterenol aerosol on exercise-induced asthma

Ten asthmatic subjects performed two exercise tests two hours apart on two separate days after inhalation of metaproterenol metered dose aerosol (1.5 mg) or placebo. Metaproterenol was effective in preventing exercise-induced asthma when administered 15 minutes before exercise but the duration of this protective effect was less than two hours in most subjects.