This study described in the present protocol consists of two parts. Part A is a multiple ascending dose study to evaluate the safety, tolerability and pharmacokinetics of ascending doses of GSK1144814. The study is a single blind, randomised, placebo controlled design in healthy male and female (of non childbearing potential) subjects. Part B is an open label design in healthy male subjects to assess the GSK1144814 Neurokinin 1 receptor occupancy after repeat oral dosing by positron emission tomography scanning with [11C] GR205171.