Aerosolized clenbuterol (NAB 365) and salbutamol in exercise-induced asthma

The effect of clenbuterol (NAB 365) in inhibiting exercise-induced asthma was compared with that of salbutamol in a single-blind, placebo-controlled, crossover study. Single doses of 20 microgram clenbuterol and 200 microgram salbutamol were given by inhalation 180 minutes before exercise to 9 patients. The exercise used was treadmill running. Clenbuterol offered complete protection to 7 patients, partial protection to 1 and no protection to 1 patient. Salbutamol offered complete protection to 5 patients, partial protection to 1 and no protection to 3 patients. One patient was not protected by any treatment. The protective effects of the two beta-adrenergic bronchodilator drugs were similar (p = 0.42 for FEV1 and p = 0.10 for FEF25-75%). Placebo failed to prevent exercised-induced asthma in any patient. No adverse reactions were manifested or reported by the patients.