Inhaled Fluticasone Furoate/Vilanterol Safety and Tolerability, PK and PD Study

Inclusion Criteria

• Healthy as determined by a study physician, based medical history, physical examination, laboratory testing, and electrocardiogram (ECG); with no significant medical condition apart from asthma, eczema, or rhinitis. A subject with a clinical abnormality or laboratory parameters outside the reference range for this study may be included if the Investigator and GSK Medical Monitor agree the finding is unlikely to introduce additional risk factors or interfere with the study procedures.
• Male and pre-menarchial female subjects aged 5 to less than 12 years on the last planned treatment day are eligible for this study. Pre-menarchial females are defined as any female who has not begun menses and is considered Tanner Stage 2 or less.
• Diagnosis of asthma at least 6 months prior to screening.
• Stable asthma therapy (fluticasone propionate, total daily dose less than or equal to 400 microgram or equivalent) and short acting beta-agonist (SABA) inhaler for at least 4 weeks prior to screening.
• Subjects must be controlled on their existing asthma treatment at screening, which will be continued during the run-in, washout and run-out periods (but not during active treatment periods). Control is defined as a Childhood Asthma Control Test score of >19 and (Peak Expiratory Flow) PEF more than 75 percent predicted.
• Subjects must demonstrate an ability to accept and effectively use a demonstration inhaler from the demonstration kits provided.
• Subjects must weigh at least 20 kilograms.
• The subject and parent/guardian are able to understand and comply with protocol requirements, instructions, and protocol stated restrictions. The parent or guardian must have the ability to read, write, and record diary information collected throughout the study. The parent or guardian must have the ability to manage study drug administration and PEF assessments.
• At least one parent/guardian has signed and dated the written informed consent prior to admission to the study. This will be accompanied by informed assent from the subject for children aged 7 to 11 years.

Exclusion Criteria

• Subjects with a history of life-threatening asthma, an asthma exacerbation requiring systemic corticosteroids or Emergency Room attendance (within 3 months) or requiring hospitalization (within 6 months) prior to screening.
• Subjects with any medical condition or circumstance making the volunteer unsuitable for participation in the study.
• Culture-documented or suspected bacterial or viral infection of the upper or lower respiratory tract, sinus, or middle ear, not resolved within 4 weeks of screening leading to a change in asthma management; or, in the opinion of the investigator, is likely to affect the subject's asthma status or ability to participate in the study.
• Clinical visual evidence of oral candidiasis at screening.
• Subjects currently receiving (or have received within 4 weeks of screening) asthma therapies including theophyllines, long-acting inhaled beta-agonists, oral beta-agonists, or who have changed their asthma medication within 4 weeks of screening.
• Significant abnormality of rate, interval, conduction or rhythm in the 12-lead ECG (electrocardiogram), determined by the investigator in conjunction with the age and gender of the child and the assessment provided by the remote analysis service.
• QTcF (QT interval corrected for heart rate using Fridericia's formula) more than 450 milliseconds or an ECG not suitable for QT measurement (e.g. poorly defined termination of the T wave).
• Aspartarte aminotransferase, Alanine aminotransferase, alkaline phosphatase and bilirubin more than 1.5 times Upper Limit of Normal (ULN) (isolated bilirubin more than 1.5 times ULN is acceptable if bilirubin is fractionated and direct bilirubin less than 35 percent).
• A known or suspected sensitivity to any constituents of the novel dry powder inhaler (i.e. lactose or magnesium stearate) (e.g. history of severe milk protein allergy)
• Any a