Both metaproterenol sulfate and albuterol are inhaled medications commonly used to prevent exercise-induced bronchospasm. Their efficacy and duration of action in controlling exercise-induced bronchospasm were compared with placebo in 18 asthmatic children (age range: 12 to 17 years) in a single-blind randomized crossover study. Standardized treadmill exercise challenges were repeated every two hours for up to six hours following the initial exercise test. With the initial exercise challenge, both active medications blocked exercise-induced bronchospasm with equal efficacy. On the other hand, when the duration of action of the medications was compared: (1) albuterol blocked exercise-induced bronchospasm longer than metaproterenol sulfate in eight subjects, (2) the reverse was true in only one patient, and (3) the medications blocked for equal duration in nine subjects. Thus, although both active agents were equally efficacious in blocking exercise-induced bronchospasm initially, the duration of action of albuterol was significantly (P < .05) longer on serial testing than that of metaproterenol sulfate. Both medications were significantly better than placebo in efficacy and duration of action.
Methacholine Dose-Response Slopes from Maximal Bronchial Challenge Tests in Asthmatic Children: Methodological Aspects