The study objective is to compare the efficacy and safety of albuterol in a dry powder inhaler (DPI) and albuterol in an HFA metered dose inhaler (MDI) after a cumulative dose of 1440mcg administered as 1+1+2+4+8 inhalations (90mcg per inhalation). Another study objective is to compare the pharmacokinetics (metabolism) of albuterol with the two inhalers. The pharmacokinetics of albuterol will be examined in half (24) of the study subjects. To participate in the study, patients must provide written informed consent, washout any prohibited medications and pass all the screen criteria. Once this is done, there will be two treatment visits. At each visit the subject will inhale with both types of inhalers. At each visit, one inhaler will have active drug (albuterol) and one inhaler will have placebo (dummy). The inhaler with the active drug will be switched at the two visits in a random manner. At each visit the subject will inhale with each inhaler a total of 16 times by a specific schedule. The subject will inhale from each inhaler once (1), wait 30 minutes, inhale from each inhaler once (1), wait 30 minutes, inhale from each inhaler twice (2), wait 30 minutes, inhale from each inhaler four times (4), wait 30 minutes, and then inhale from each inhaler eight times (8). The total time to complete the inhalations should be about 2 hours. Following that, there will be a series of assessments taken at regular times with vital signs measured up to 6 hours, ECG (electrocardiogram) assessed up to 4 hours, blood taken to measure potassium and glucose up to 4 hours, lung function evaluated with spirometry up to 6 hours, and for those subjects participating in the pharmacokinetic evaluation blood will be drawn up to 12 hours. The two study treatment visits will be 3 to 14 days apart. Following these visits, there will be a study concluding visit 1 to 5 days later.
