THE EFFECT OF REGULAR INHALED ALBUTEROL ON EXERCISE-INDUCED BRONCHOCONSTRICTION

Pretreatment with inhaled beta(2)-agonists is often recommended for th e prevention of exercise-induced bronchoconstriction. Regular treatmen t with inhaled beta(2)-agonists has been associated with worsened base line airway caliber and increased airway responsiveness. In this study , we have investigated the effects of regular inhaled albuterol on the severity of exercise-induced bronchoconstriction using a double-blind , placebo-controlled, randomized, crossover design. Ten subjects inhal ed either albuterol or placebo (2 x 100 mu g, four times per day) for 7 d. On the eighth and ninth days of treatment periods, subjects perfo rmed 5-min constant work rate cycle ergometry exercise challenges afte r inhaling 200 mu g of placebo (eighth day) or albuterol (ninth day). Forced expired volume in 1 s (FEV(1)) was measured on arrival in the l aboratory as well as before and for 1 h after exercise. One week of re gular inhaled albuterol compared with placebo resulted in: (I)a lower baseline FEV(1) (mean difference, 230 ml)(p = 0.02); (2) a lower minim um postexercises FEV(1) without inhaled albuterol pretreatment (mean d ifference, 390 ml; range, -50 ml to 1,250 ml)(p = 0.01); (3) a lower m inimum postexercise FEV(1) with inhaled albuterol pretreatment (p < 0. 01). The smallest degree of exercise-induced bronchoconstriction occur red after a week of regular placebo and pretreatment with inhaled albu terol immediately before exercise, Inhalation of albuterol four times daily for 1 wk worsens exercise-induced bronchoconstriction; however, it remains extremely effective when used immediately before exercise f or preventing bronchoconstriction.