Pharmacokinetics of Darunavir/Ritonavir and TMC125 alone and Coadministered in HIV-Negative Volunteers

Objective To evaluate the pharmacokinetics of TMC125 (etravirine) and darunavir (DRV) with low-dose ritonavir (DRV/r). Design Open-label, randomized, two-way crossover Phase I trial. Methods Thirty-two HIV-negative volunteers were randomized 1:1 to two panels. All received TMC125 100 mg twice daily for 8 days and, after 14 days washout, DRV/r 600/100 mg twice daily for 16 days. During days 9–16, TMC125 100 or 200 mg twice daily was coadministered (Panel I or II, respectively). Results Twenty-three volunteers completed the trial. With DRV/r coadministration, mean exposure (area under the plasma concentration-time curve from 0 to 12 h [AUC 12h ]) to TMC125 given as 100 mg twice daily was decreased by 37%; maximum and minimum plasma concentrations (C max and C min ) were decreased by 32% and 49%, respectively. For TMC125 200 mg twice daily coadministered with DRV/r, AUC 12h , C max and C min of TMC125 were 80%, 81% and 67% greater, respectively, versus TMC125 100mg twice daily alone. DRV pharmacokinetics were unchanged except a 15% increase in AUC 12h when given with TMC125 200 mg twice daily. Conclusions No clinically relevant changes in DRV pharmacokinetics were observed when combined with TMC125; therefore DRV dose adjustment is not required. Coadministration of TMC125 100 mg twice daily with DRV/r decreased TMC125 exposure by 37%. The increase of TMC125 exposure by 80% when given as 200 mg twice daily reflects the higher dose and the interaction with DRV/r. The magnitude of this interaction is comparable to TMC125 interactions with other boosted PIs observed in Phase IIb trials in HIV-1-infected patients. As these trials demonstrated TMC125 efficacy, no dose adjustment of TMC125 is needed when combined with DRV/r.