2. Patients with a Forced Expiratory Volume in one second (FEV1) at Visit 1 of ≥50% of the predicted normal value for the patient. This criterion for FEV1 will have to be demonstrated after a washout period of at least 6 hours during which no short acting β2-agonist has been inhaled, and a minimum of 48 hours for a long acting β2-agonist.