Mean increase in FEV1 from baseline in patients treated with either formoterol or budesonide/formoterol. At screening (t = -20 minutes), salbutamol 400 μg was administered to all patients to establish their relative refractoriness to β2-agonist therapy. Patients in the formoterol group received formoterol 9 μg, 2 inhalations at t = -5 minutes and 2 inhalations at 0 minutes (total dose 36 μg). Patients treated with budesonide/formoterol received budesonide/formoterol 320/9 μg, 2 inhalations at t = -5 minutes and 2 inhalations at 0 minutes (total dose 1280/36 μg). The timing of study drug administration is shown by vertical dotted lines on the figure. Patients received oral prednisolone 60 mg 90 minutes after the last administration of study drug.