Because a significant proportion of COPD subjects are prescribed proton pump inhibitors (PPI's) such as omeprazole in order to alleviate symptoms of gastro-esophageal reflux disease (GERD), it is important to understand the absorption of the current formulation of GSK1325756 in an environment of raised intra-gastric pH as will be encountered in patients taking PPI's. Therefore, this study will also evaluate the impact of the proton pump inhibitor omeprazole on the pharmacokinetics of GSK1325756.