A 12-Week Study to Evaluate the 24-Hour Pulmonary Function Profile of Fluticasone Furoate/Vilanterol (FF/VI) Inhalation Powder 100/25 mcg Once Daily Compared With Fluticasone Propionate/Salmeterol Inhalation Powder 250/50 mcg Twice Daily in Subjects With Chronic Obstructive Pulmonary Disease (COPD)

This will be a Phase IIIb multicentre, randomized, double-blind, double-dummy, 12-week parallel group study evaluating the effects of once daily in the morning treatment of FF/VI Inhalation Powder versus Fluticasone Propionate/Salmeterol Inhalation Powder twice daily on lung function in COPD subjects. Subjects will be screened and will enter a 2-week, single-blind (placebo), Run-In Period to evaluate the subject's adherence with study treatment, study procedures and assessment of disease stability. At the end of the Run-In Period, subjects will return to the Clinic and who meet all of the Randomization Criteria will be randomized to double-blind study medication (12-week treatment period). Subjects will be randomized to receive either FF/VI 100/25 via NDPI or Fluticasone Propionate/Salmeterol 250/50mcg via ACCUHALER/DISKUS. Matching placebos will be available in NDPI and ACCUHALER/DISKUS. Each morning (approximately 6-10 AM) subjects will take 1 inhalation from the NDPI followed by 1 inhalation from the ACCUHALER/DISKUS. Each evening (approximately 6-10 PM), approximately 12 hours after the morning dose with blinded study medication, subjects will take 1 inhalation from the ACCUHALER/DISKUS. Subjects will return to the clinic at the end of the treatment period. A follow-up phone contact will be performed approximately 7 days after the last clinic visit. The overall study duration (Screening to Follow-up) for each subject is approximately 15 weeks.