Many of these patients will be receiving long-acting beta2-agonists and this therapy will be discontinued for 48h before starting the run-in. In addition, the following therapies are not allowed: 1) anticholinergics; 2) theophylline; 3) oral beta2-agonists; 4) antihistamines; 5) inhaled cromolyn sodium or nedocromil; 6) leukotriene antagonists.