This was a Phase III, multicenter, randomized, double-blind, placebo- and active-controlled, parallel-group study of up to 9 weeks in duration. Seven days of QID single-blind placebo administration (via MDI) was followed by 56 days of QID double-blind active treatment. Following the run-in period, each subject was randomized to one of the following three treatments: levalbuterol HFA MDI 90 mcg (2 actuations of 45 mcg), racemic albuterol HFA MDI 180 mcg (2 actuations of 90 mcg), or placebo (2 actuations). Subjects were randomized in a 2:1:1 ratio of levalbuterol to racemic albuterol to placebo. In order to maintain blinding of the device, a placebo dose was administered with each treatment. This study was previously posted by Sepracor Inc. In October 2009, Sepracor Inc. was acquired by Dainippon Sumitomo Pharma., and in October 2010, Sepracor Inc's name was changed to Sunovion Pharmaceuticals Inc.