GSK1349572 is an integrase inhibitor that is currently in Phase 2 clinical trials for the treatment of HIV infection. As GSK1349572 development progresses, it may be dosed with non-nucleoside HIV reverse transcriptase inhibitors (NNRTIs) including efavirenz (EFV, Sustiva). Efavirenz is a known inducer of CYP3A4. GSK1349572 is primarily metabolized via UGT1A1, however it also has a CYP component to its metabolism, thus a drug interaction between GSK1349572 and EFV is likely. A previous study showed that another NNRTI, etravirine which is also a known inducer of CYP3A and UGT, reduced GSK1349572 exposure significantly. GSK1349572 is not an inhibitor or inducer of CYP3A and is not expected to have impact on pharmacokinetics (PK) of EFV.