The protective effect of clenbuterol on exercise-induced asthma was studied in 14 patients with aspecific bronchial hyperreactivity. The selectivity of clenbuterol for beta2-receptors was also studied.
After the preliminary measurements (a), oral clenbuterol was started (0.02 mg × 2/day) and measurements were repeated after 30 (b) and 60 days (c) of therapy. During treatment, physical exercise did not significantly influence the indexes of respiratory function. Similarly systolic time intervals and polycardiographic indexes did not change significantly with respect to the initial values. A small increase in heart rate at rest was observed in (b); however, no significant changes were recorded in (c) compared with the initial values.
Clenbuterol seems to offer an effective protection against exercise-induced asthma without the negative effects on the cardiovascular system which may arise from activation of beta1-adrenergic receptors.
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