Long-acting Beta Agonist Step Down Study

Inclusion Criteria: * age 12-80 years * physician diagnosed asthma that is well-controlled on moderate dose ICS/LABA based on an Asthma Control Test (ACT) score more than or equal to 20, and the absence of unscheduled visits or use of rescue prednisone for 4 weeks prior to enrollment * pre-bronchodilator FEV1 (forced expiratory volume in 1 second) more than or equal to 70% predicted Exclusion Criteria: * chronic oral steroid therapy * hospitalization or urgent care visit within 4 weeks of the screening visit * lung disease other than asthma including COPD, bronchiectasis, sarcoidosis or other lung disease * less than 10 pack/yr of tobacco use and abstinence for at least 1 yr * history of extensive environmental tobacco exposure or occupational exposure suggestive of possible COPD (chronic obstructive pulmonary disease) per judgment of investigator * post bronchodilator FEV1 less than 70% predicted * near fatal asthma (intubation or ICU admission for asthma) within 2 yrs of enrollment * high risk of near fatal or fatal asthma * history of known premature birth less than 33 weeks or any significant level of respiratory care including prolonged oxygen administration or mechanical ventilation during the neonatal period * unstable cardiac disease (decompensated congestive heart failure, unstable angina, recent myocardial infarction, atrial fibrillation, supraventricular or ventricular tachycardia, congenital heart disease, or severe uncontrolled hypertension) * other major chronic illnesses which in the judgment of the study physician would interfere with participation in the study e.g. including but not limited to uncontrolled diabetes, uncontrolled HIV infection or other immune system disorder * drug allergies to any component of study drug or history of adverse reaction to short or long acting beta agonists * for women of child bearing potential; not pregnant, not lactating and agree to practice an adequate birth control method (abstinence, combination barrier and spermicide, or hormonal) for the duration of the study