- Patients who have a documented forced expiratory volume at 1 second (FEV1) reversibility of at least 12% over baseline value following administration of a bronchodilator (i.e. "historical" reversibility) or demonstrate a >12% increase in FEV1 over their baseline value within 30 minutes after inhalation of up to 360 µg (4 puffs) of albuterol at Visit 1. The administration of albuterol for the reversibility test must be within 30 minutes after baseline spirometry.