- All patients must have an improvement in FEV1 not less than 12 % above baseline and an absolute change of at least 200 mL within 15-30 min after administration of 400 mcg salbutamol/albuterol Hydrofluoroalkane (HFA) Metered Dose Inhaler (MDI). When the reversibility is not achieved at Visit 1, there will be the option to repeat reversibility test at any visit during the run-in period.