ritonavir and Etravirine Interactions

Interactions between ritonavir and Etravirine (etravirine)

ritonavir and etravirine (Major Drug-Drug)

GENERALLY AVOID: Coadministration with full-dose ritonavir (600 mg twice a day) may significantly decrease the plasma concentrations of etravirine. The mechanism of interaction has not been described but may involve ritonavir induction of CYP450 2C19 and 2C9, of which etravirine is a substrate. In 11 study subjects administered etravirine with ritonavir 600 mg twice a day, etravirine peak plasma concentration (Cmax) decreased by 32% and systemic exposure (AUC) decreased by 46%.

MANAGEMENT: Given the risk of reduced viral susceptibility and resistance development associated with subtherapeutic antiretroviral drug levels, the use of etravirine in combination with full-dose ritonavir should be avoided. Etravirine may be used with low-dose ritonavir administered as a pharmacokinetic booster in certain protease inhibitor regimens.