GSK1349572 Drug Interaction Study With Fosamprenavir/Ritonavir

GSK1349572 is an integrase inhibitor being developed for the treatment of human immunodeficiency virus (HIV)-1 infection by GlaxoSmithKline (GSK) on behalf of Shionogi-ViiV HealthcareLLC. In HIV-infected patients where combination antiretroviral therapy is the standard of care, it is likely that it will be dosed with boosted protease inhibitors (PIs) including fosamprenavir/ritonavir (FPV/RTV or FPV/r). As FPV and RTV are modulators (induction as well as inhibition) of Uridine diphosphate glucuronosyltransferase (UGT) and Cytochrome P450 (CYP)3A which are the primary and secondary metabolic pathways of GKS1349572, it is likely that FPV/RTV will affect the pharmacokinetics (PK) of GSK1349572, therefore a drug interaction study is warranted and will be evaluated in Part A of this study. Part B will evaluate the effect of particle size of tablet variants on the PK of GSK1349572. In Part A, approximately 12 subjects will receive GSK1349572 50mg every 24 hours (q24h) for 5 days (Treatment A). Subjects will then be administered GSK1349572 50mg q24h in combination with FPV/RTV 700/100 mg every 12 hours (q12h) (Treatment B) for 10 days. There will be no washout between treatments. In Part B 15 subjects will receive a single 50 mg dose (2 x 25mg tablet) in 3 different tablet variants of the same formulation, differing only in particle sizes of GSK1349572, under fasted conditions in a three-way crossover design. Safety evaluations and serial PK samples will be collected during each treatment period. A follow-up visit will occur 7-14 days after the last dose of study drug.