RESUMEN
BACKGROUND: Inhaled short-acting beta(2)-adrenoceptor agonists are the most commonly used treatment for the prevention of exercise-induced bronchoconstriction (EIB). Formoterol, a long-acting beta(2)-adrenoceptor agonist, has been demonstrated to provide protection from EIB, although the onset and duration of this protection have not been defined. OBJECTIVE: The purpose of this study was to determine the onset and duration of the protective effect of a single dose of inhaled formoterol powder against EIB, comparing them with the effect of a single dose of placebo and albuterol administered via metered-dose inhaler (MDI). METHODS: In this double-dummy, 4-way crossover study, patients received single doses of formoterol (12 and 24 microg) via a powder inhaler, albuterol by MDI (180 microg), and placebo. Exercise challenge tests (ECTs) were conducted at 15 minutes and at 4, 8, and 12 hours postdose. Pulmonary function studies (forced expiratory volume in 1 second [FEV(1)] and peak expiratory flow rate) were performed before and after each exercise challenge. RESULTS: Twenty adolescent and adult patients (mean age, 23.8 years; range, 13-41 years; 9 male, 11 female) with asthma were enrolled in the study, and 17 completed all 4 treatment sequences. Compared with placebo, both doses of formoterol produced significantly greater inhibition of FEV(1) decreases at all time points (P < 0.01). There were no significant differences in efficacy measures between the 2 formoterol doses throughout the study. The exercise-induced decrease in FEV(1) after albuterol treatment was significantly reduced compared with placebo only at 15 minutes after dosing (P < 0.05). Formoterol and albuterol exhibited a similar rapid onset of action (<15 minutes), but formoterol continued to protect patients against EIB for at least 12 hours (P < 0.01), whereas albuterol was no longer clinically effective by the 4-hour ECT. CONCLUSIONS: Formoterol and albuterol, given as single-dose inhalations, both provided protection from EIB within 15 minutes in this group of patients. The bronchoprotection afforded by formoterol lasted up to 12 hours, whereas that of albuterol was no longer significant by 4 hours.