A Randomised, Double-blind, Double-dummy, Parallel-group Multicentre Study to Assess Efficacy and Safety of Fluticasone Furoate/GW642444 Inhalation Powder and Fluticasone Propionate/Salmeterol Inhalation Powder in the Treatment of Persistent Asthma in Adults and Adolescents

The purpose of the study is to compare the efficacy and safety of fluticasone furoate/vilanterol (GW642444) inhalation powder administered once daily with fluticasone propionate/salmeterol administered twice daily in adolescent and adult subjects 12 years of age and older with persistent bronchial asthma over a 24-week period.