Study to Evaluate the 24-Hour Pulmonary Function Profile of Fluticasone Furoate (FF) /GW642444 (Vilanterol) (VI) Inhalation Powder 100/25mcg Once Daily Compared With Fluticasone Propionate/Salmeterol Inhalation Powder 250/50mcg Twice Daily in Subjects With Chronic Obstructive Pulmonary Disease

The purpose of this study is to evaluate the 24-hour spirometry effect (FEV1) of FF/VI 100/25mcg once daily compared with Fluticasone Propionate/Salmeterol 250/50mcg twice daily over a 12-week treatment period in subjects with COPD.

This is a randomized, double-blind, double-dummy, multi-centre parallel group study. Subjects who meet the eligibility criteria at Screening and meet the randomization criteria at the end of a 2-week Run-In period will enter a 12-week treatment period. There will be a 7-day Follow-up period after the treatment period.

Eligibility Criteria:
Inclusion Criteria:

* Signed and dated written informed consent
* Male or females ≥ 40 years of age
* Established clinical history of COPD by ATS/ERS definition
* Females are eligible to enter and participate if of non-childbearing potential, or if of child bearing potential, has a negative serum pregnancy test at screening, and agrees to one of the acceptable contraceptive methods listed in protocol, used consistently and correctly
* Former or current smoker \> 10 pack years
* Post-albuterol spirometry criteria: FEV1/FVC ratio ≤ 0.70 and FEV1 ≤ 70% of predicted normal (NHANES III)

Exclusion Criteria:

* Current diagnosis of asthma
* Subjects with other respiratory disorders including active tuberculosis, α1-antitrypsin deficiency, lung cancer, bronchiectasis, sarcoidosis, lung fibrosis, pulmonary hypertension, interstitial lung diseases or other active pulmonary diseases
* Lung volume reduction surgery within previous 12 months
* Clinically significant abnormalities not due to COPD by chest x-ray
* Hospitalized for poorly controlled COPD within 12 weeks of Screening
* Poorly controlled COPD 6 weeks prior to Screening, defined as acute worsening of COPD that is managed by the subject with corticosteroids or antibiotics or that requires treatment prescribed by a physician
* Lower respiratory infection requiring antibiotics 6 weeks prior to Screening
* Uncontrolled or clinically significant (in opinion of PI) cardiovascular, hypertension, neurological, psychiatric, renal, hepatic, immunological, endocrine, peptic ulcer disease, or hematological abnormalities
* Carcinoma not in complete remission for at least 5 years
* Subjects with history of hypersensitivity to study medications (e.g., beta-agonists, corticosteroid) or components of inhalation powder (e.g., lactose, magnesium stearate)
* Subjects with history of severe milk protein allergy that, in opinion of study physician, contraindicates subject's participation
* Known/suspected history of alcohol or drug abuse in the last 2 years
* Women who are pregnant or lactating or plan to become pregnant
* Subjects medically unable to withhold albuterol and/or ipratropium 4 hours prior to spirometry testing at each study visit
* Use of certain medications such as bronchodilators and corticosteroids for the protocol-specific times prior to Visit 1 (the Investigator will discuss the specific medications)
* Long Term Oxygen Therapy (LTOT) or nocturnal oxygen therapy \>12 hours a day
* Participation in the acute phase of a pulmonary rehabilitation program within 4 weeks prior to Screening or during the study
* Non-compliance or inability to comply with study procedures or scheduled visits
* Affiliation with investigator site