Escalating and Cumulative-Dose Study of Pharmacokinetics (PK), Pharmacodynamics (PD) and Safety of A006

Inclusion Criteria: * Body weight ≥ 50 kg for men and ≥ 45 kg for women, and BMI within the range of 18.5 - 30.0 kg/m2 inclusive; * Sitting blood pressure ≤ 135/90 mmHg; * Demonstrating negative alcohol/drug screen tests; * Demonstrating negative HIV, HBsAg and HCV-Ab screen tests; * With mild-to-moderate persistent asthma for at least 6 months prior to Screening, and having used inhaled β-agonist(s) for asthma control; * Demonstrating a Mean Screening Baseline FEV1 at 50.0 - 85.0 % of predicted normal; * Demonstrating a ≥ 15.0% Airway Reversibility in FEV1 within 30(±5) min after inhaling 2 actuations of Proventil-HFA; * Demonstrating Peak Inspiratory Flow Rate within 80-150 L/min; * Demonstrating proficiency in the use of DPI and MDI after training; * Females of child-bearing potential must be non-pregnant, non-lactating, and practicing a clinically acceptable form of birth control; * Having properly consented to participate in the trial. Exclusion Criteria: * Smoking history of ≥ 10 pack-years, or having smoked within 6 months prior to Screening; * Upper respiratory tract infections within 2 wk, or lower respiratory tract infection within 4 wk; * Asthma exacerbations that required emergency care or hospitalized treatment, within 4 wk prior; * Any current or recent respiratory conditions that might significantly affect pharmacodynamic response to the study drugs, besides asthma; * Concurrent clinically significant cardiovascular, hematological, renal, neurologic, hepatic, endocrine, psychiatric, malignancies, or other illnesses that could impact on the conduct, safety and evaluation of the study; * Known intolerance or hypersensitivity to any of the ingredients of the A006 or Proventil-HFA; * Use of prohibited drugs or failure to observe the drug washout restrictions; * Having been on other clinical drug/device studies in the last 30 days; * Having donated blood within the last 30 days prior to Screening.