A Study in Asthmatic Patients to Determine if There is Any Difference in Dosing With Fluticasone Furoate/Vilanterol Inhalation Powder in the Morning or Evening on Lung Function

This study will be a repeat-dose, double-blind, randomized, placebo controlled, three-way crossover study in patients with persistent bronchial asthma to compare the effect of morning (AM) and evening (PM) dosing with fluticasone furoate (FF)/Vilanterol (VI) inhalation powder on lung function. Following screening there will be a run-in period of 14 days. There will be 3 treatment periods; drug at AM, drug at PM and placebo, which will last for 14 days each with a 14-21 day washout period between starting the next. Key assessments include; forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), vital signs, electrocardiograms (ECGs), adverse event (AE) monitoring and laboratory safety tests.