This was an open-label study conducted over 1 to 2 h for each participant on a single day. After we obtained baseline spirometry, heart rate, and BP measurements, participants received two inhalations of albuterol (90 μg per inhalation) from an MDI attached to a holding chamber (InspirEase; Schering-Plough Corporation; Kenilworth, NJ). Additional inhalations of 90 μg through the holding chamber were administered every 15 min, with spirometry, heart rate, and BP measured immediately prior to each dose. When there was no further improvement in FEV1 (< 100 mL change from the highest FEV1 obtained after the previous dose), each participant received a single 2.5-mg dose of nebulized albuterol. Final spirometry, heart rate, and BP measurements were obtained 15 min after nebulized albuterol. The cumulative doses of albuterol administered from the MDI were 180 μg, 270 μg, 360 μg, 450 μg, 540 μg; and the cumulative doses from the MDI plus nebulizer were 270 μg MDI plus 2,500 μg nebulized (2,770 μg); 360 μg MDI plus 2,500 μg nebulized (2,860 μg); 450 μg MDI plus 2,500 μg nebulized (2,950 μg); and 540 μg MDI plus 2,500 μg nebulized (3,040 μg). The number of participants receiving each dose and the cumulative administered doses (MDI and MDI plus nebulized) are shown in Figure 1. These doses represent the amount of drug administered to the patient from each device.