This is a first time in human study to investigate the safety of GSK626616AC given as oral single and repeat doses in healthy subjects. An additional group of subjects will be assessed to determine the effect of several drugs given at the same time as GSK626616.

Inclusion Criteria:

• Age 18 to 55 years healthy subjects
• Hemoglobin values of 13.5-17.0 g/dL for males or 12.0-15.5 g/dL for females.
• Females cannot be pregnant.

Exclusion Criteria:

• Cannot have exposure to greater than 4 new chemical entities within 12 months.
• Cannot have a clinical history of current alcohol, or illicit drug use which, in the judgment of the Investigator, would interfere with the subject's ability to comply with the dosing schedule.
• Cannot have a history of regular use of tobacco- or nicotine-containing products within 3 months.
• Must not have received a blood transfusion or had a donation of blood within 3 months prior to study entry.
• Cannot use be taking prescription, non-prescription or illicit drugs.