Pharmacodynamic Bioequivalence Study of Albuterol Sulfate Inhalation Aerosol, 0.09 mg Albuterol Base/ Inhalation

Inclusion Criteria: 1. Male and non-pregnant female subjects (18-65 years of age). 2. Stable mild asthmatics based on National Asthma Education and Prevention Program (NAEPP) guidelines. 3. FEV1 ≥ 80% of predicted. 4. Airway responsiveness to methacholine demonstrated by a pre-albuterol dose (baseline) PC20 ≤ 8 mg/mL or equivalent PD20. 5. Nonsmokers for at least six months prior to the study and a maximum smoking history of five pack-years (the equivalent of one pack per day for five years). 6. Written informed consent. Exclusion Criteria: 1. Evidence of upper or lower respiratory tract infection (e.g., pneumonia, bronchitis, sinusitis) within six weeks prior to the study. 2. History of seasonal asthma exacerbations, in which case the subject should be studied outside of the relevant allergen season. 3. History of cystic fibrosis, bronchiectasis or other respiratory diseases. 4. History of cardiovascular, renal, neurologic, liver or endocrine dysfunction, including ECG with evidence of ischemic heart disease. 5. Treatment in an emergency room or hospitalization for acute asthmatic symptoms or need for daily oral corticosteroids within past three months. 6. Known intolerance or hypersensitivity to any component of the albuterol MDI