The completed clinical studies demonstrated that to minimize inter-subject variability of the exposure to GSK1325756, the current formulation needs to be administered with food, particularly in elderly subjects. This does not preclude development of the current formulation, but is not ideal, particularly if twice daily administration is needed in chronic obstructive pulmonary disease (COPD) patients and for elderly subjects in which food intake can be variable. In addition, the inter-subject variability in exposure with the current formulation when given with omeprazole in the fasted state is not acceptable. This is likely due to the need for a low pH (acid level) (pH < 2) gastric environment, particularly in the fasted state, to allow for sufficient solubilization of the GSK1325756 prior to transport to the small intestine where it is absorbed. Thus, this study is being conducted for the following reasons: (1) to determine if the current formulation results in acceptable exposure and inter-subject variability if given with food in subjects in which gastric acid secretion is suppressed with omeprazole and (2) to determine if a bio-enhanced formulation can provide an acceptable exposure profile and acceptable inter-subject variability in the fasted state in subjects in which gastric acid is suppressed. This information will be important in helping to determine the appropriate formulation and dosing regimen for progression to studies in COPD patients.