GSK1349572 Drug Interaction Study With Efavirenz

Study Summary

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. This study will investigate the dose proportionality between single doses of 50mg and 100mg of GSK1349572 and will compare steady-state plasma PK, safety and tolerability of GSK1349572 50 mg every 24h (q24h) with and without efavirenz 600 mg q24h. Approximately 12 subjects will receive a single dose of GSK1349572 100 mg (Treatment A) in Period 1 followed by a washout of greater than or equal to 6 days. In Period 2 subjects will receive GSK1349572 50mg q24h for 5 days (Treatment B). Subjects will then be administered GSK1349572 50mg q24h in the morning in combination with EFV 600 mg q24h (Treatment C) in the evening for 14 days in Period 3. There will be no washout between Periods 2 and 3. Safety evaluations and serial PK samples for GSK1349572 will be collected during each treatment period. A follow-up visit will occur 7-14 days after the last dose of study drug. This study will be conducted at one center in the US, with healthy adult male and female subjects.

Primary Outcome

Plasma GSK1349572 PK parameters: AUC(0-24), Cmax, and C24, and dose-normalized AUC(0-24), Cmax, and C24 following single dose administration of 100mg and 50mg.

Interventions

• DRUG Efavirenz
• DRUG GSK1349572