A randomized, double-blind, active-controlled multicenter, two-way crossover study of HFA levalbuterol (with and without a spacer) in subjects 4-11 years of age with asthma. 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.