The primary objective of this study is to evaluate the relative bioavailability, including the inter-subject variability, of the immediate release (IR) tablet used for the previous Phase I studies and 2 prototype bioenhanced tablet formulations of GSK1325756 in healthy elderly male and female subjects under fed and fasted states during suppression of gastric acid secretion (concomitant omeprazole, 20 mg, once daily (QD)). Secondary objectives include provision of information on the oral pharmacokinetic (PK) of GSK1325756 in the elderly under different dosing conditions during suppression of gastric acid secretion, and additional safety and tolerability information for oral administration of GSK1325756 in elderly subjects.