To compare intracellular and plasma etravirine concentrations when etravirine was given at 200 mg/12 h versus 400 mg/24 h and to evaluate whether the results would support once-daily dosing.Methods
This was an open-label sequential study in which eight patients on protease inhibitor (PI)-sparing regimens containing etravirine were included. Full pharmacokinetic profiles were performed while on 200 mg of etravirine/12 h and after switching to 400 mg of etravirine/24 h. Intracellular and plasma levels were determined by liquid chromatography coupled with mass spectrometry. Pharmacokinetic parameters were calculated by non-compartmental analysis and compared by geometric mean ratios (GMRs) using 200 mg of etravirine/12 h as the reference group. Trial registration: ClinicalTrials.gov NCT01121809.Results
The geometric mean (GM) for etravirine AUC0–τ (5602 versus 5076 ng · h/mL, GMR 0.91), Cmax (403 versus 495 ng/mL, GMR 1.23) and Cmin (139 versus 102 ng/mL, GMR 0.74) were similar with both dosing schedules at the intracellular level. In plasma, the GMRs for AUC0–τ, Cmax and Cmin were 1.31, 1.76 and 0.99, respectively. The mean intracellular penetration, evaluated as intracellular and plasma AUC0–τ ratios, was 81% when etravirine was dosed twice daily and 56% with once-daily dosing.Conclusions
Our results show that intracellular etravirine levels were similar with both dosing regimens in patients with PI-sparing regimens, while etravirine plasma AUC0–τ and Cmax were 30% and 76% higher with the once-daily regimen, respectively. Thus, a once-daily dosing regimen is supported not only by plasma etravirine pharmacokinetic profiles but also by intracellular levels.