- FEV1 reversibility of at least 12% following bronchodilator administration (4 puffs) at study visit 1. Individuals will need to hold albuterol, montelukast, theophylline, ipratropium bromide (or other anticholinergics) and LABAs per study instructions prior to reversibility testing. If an individual is receiving these types of medications prior to study visit 1, he/she may be brought back to the clinical center within 1 week following appropriate medication withholding to attempt qualification by reversibility criteria. If the individual does not meet this requirement, they may qualify for enrollment if their PC20 methacholine FEV1 is less than or equal to 12.5 mg/ml at the time of randomization. If FEV1 is less than 70%, thus precluding the methacholine challenge at this visit, then completion of the visit will be postponed several days and an additional attempt to obtain a methacholine challenge test will be made. If the methacholine challenge still cannot be performed, an individual may still qualify by reversibility criteria at this visit.