This is a multi-center, randomized, double-blind, double-dummy, parallel-group study to compare the efficacy and safety of Fluticasone Furoate Inhalation Powder 100mcg once daily and Fluticasone Propionate Inhalation Powder 250mcg twice daily with Placebo. Subjects will participate in the study for up to a maximum of 29 weeks (including screening, treatment and follow-up contact). The primary endpoint consists of change from baseline in clinic visit trough (pre-bronchodilator and pre-dose) FEV1 at the end of the 24 week treatment period. The nominated powered secondary endpoint is the change from baseline in the percentage of rescue-free 24 hour periods during the 24-week treatment period. Safety assessments include adverse events, oropharyngeal examinations, clinical chemistry and urine cortisol excretion. For subjects who have consented for pharmacogenetics, a blood sample will also be taken for pharmacogenetic analysis.
