SB-742457 is a 5HT6 receptor antagonist that is in development for the symptomatic treatment of mild to moderate Alzheimer's disease . To date, all clinical trials have been conducted using a capsule formulation of SB-742457. However, it is intended to conduct all futures studies with a tablet formulation. The aim of this study is to assess the pharmacokinetic profile of SB-742457 and its major metabolites following single doses of both the capsule and tablet formulations.