The purpose of this clinical research study is to compare up to 3 doses of an investigational drug GW501516 to placebo (an inactive pill that looks like GW501516) to see if it is safe, well tolerated and effective in improving (raising) low levels of "good cholesterol", high-density lipoprotein cholesterol (HDLc), as compared to placebo.

A multicentre, two-staged with interim analysis, parallel, randomised, double blind, placebo-controlled, dose-ranging study of the safety, tolerability, and effects on plasma high-density lipoprotein cholesterol (HDLc) of 12 weeks treatment with 2.5mg, 5mg and 10mg daily doses of GW501516 in subjects with low HDLc

Inclusion criteria:

• Have a fasting plasma HDLc concentration <=45mg/dL (<=1.16mmol/L), plasma LDLc levels that do not require treatment according to the National Cholesterol Education Program/Adult Treatment Panel III (NCEP/ATPÂ III) guidelines.
• Have a fasting plasma TG concentration =500mg/dL (=5.65mmol/L).

Exclusion criteria:

• Coronary heart disease.
• Diabetes mellitus.
• Atherosclerotic disease.