GSK2647544 is an orally available, selective inhibitor of Lp PLA2 that is being developed for the treatment of Alzheimer's disease. The current study is a single-blind, randomised, placebo-controlled, 4-cohort study to assess the safety, tolerability, pharmacokinetics and pharmacodynamics of repeat doses of GSK2647544. Cohorts 1, 2 and 3 will evaluate escalating doses of GSK2647544 in young healthy volunteers for 7 days, 7 days, and 14 days, respectively. Cohort 4 will evaluate repeat doses of GSK2647544 in healthy elderly volunteers for 14 days. Additionally, Cohorts 1 and 3 will include an assessment of potential drug-drug interaction with simvastatin to examine CYP3A4 inhibition by GSK2647544.