Bronchodilating effect and anabolic effect of inhaled procaterol

While the use of oral beta (2)-agonists by athletes is prohibited because of their anabolic effects, some inhaled beta (2)-agonists can be used in accordance with the World Anti-Doping Agency regulations. We examined the dose disparity between the bronchodilating effect and anabolic effect of inhaled procaterol, a selective beta (2)-agonist, to determine if the drug might be effective for athletes with asthma. Intact rats were given nebulized procaterol at 0.001, 0.01, 0.1 and 1 mg/mL by inhalation, and its inhibitory effect on carbachol-induced bronchoconstriction was evaluated. Castrated rats were given nebulized procaterol at 0.03, 0.1, 0.3 and 1 mg/mL by inhalation 3 times a day for 14 days, and anabolic markers (body weight gain, weight of the levator ani muscle and gastrocnemius muscle) were measured. At 0.01 mg/mL and higher, procaterol dose-dependently inhibited carbachol-induced bronchoconstriction with a significant effect. At doses of up to 0.3 mg/mL, there were no signs indicating an anabolic effect of procaterol. At 1 mg/mL, however, a slight but statistically significant increase in the weight of the levator ani muscle was observed with no significant changes in other anabolic markers. It was suggested that inhaled procaterol might be useful for athletes with asthma because of the big dose disparity between its bronchodilating effect and anabolic effect in rats.