Abstract
Repeated injury of the airway epithelium caused by hyperpnoea of poorly conditioned air has been proposed as a key factor in the pathogenesis of exercise-induced bronchoconstriction (EIB) in athletes. In animals, the short-acting β2-agonist terbutaline has been shown to reduce dry airflow-induced bronchoconstriction and shedding of the airway epithelial cells. Our aim was to test the efficacy of terbutaline in attenuating hyperpnoea-induced bronchoconstriction and airway epithelial injury in athletes. Twenty-three recreational athletes with EIB participated in a randomised, double-blind, placebo controlled, cross-over study. Athletes completed an 8 min eucapnic voluntary hyperpnoea (EVH) test with dry air on two separate days 15 min after inhaling 0.5 mg terbutaline or a placebo. Forced expiratory volume in 1 sec (FEV1) and urinary concentration of the Clara cell protein CC16 (a marker of airway epithelial stress) were measured before and for up to 60 min after EVH. The maximum fall in FEV1 of 18 ± 8% (SD) on placebo was reduced to 8 ± 5% following terbutaline (P<0.001). Terbutaline gave bronchoprotection (i.e., post-EVH FEV1 fall <10%) to 18 (83%) athletes. EVH caused an increase in urinary excretion of CC16 in both conditions (P<0.001), and terbutaline significantly reduced this rise (delta pre- to post-challenge CC16 increase 416 ± 495 ρg·mmol creatinine-1 after placebo vs 315 ± 523 ρg·mmol creatinine-1 after terbutaline, P=0.016). The results suggest that inhalation of a single therapeutic dose of terbutaline offers significant protection against hyperpnoea-induced bronchoconstriction and may attenuate acute airway epithelial stress in athletes.
- © 2013 ERS