Raltegravir Plasma Concentrations in Treatment-Experienced

Raltegravir, the first licensed HIV in-tegrase inhibitor, is currently ap-proved in several countries for use in combination with other antiretroviral agents for treatment of HIV-1 infection. Raltegravir is active against a wide range of wild-type and multidrug-resistant HIV-1 clinical isolates and, in combina-tion with optimized background therapy, has shown to be safe and effective in achieving immunologic recovery and vi-rologic suppression.1,2 Pharmacokinetic studies have shown that raltegravir is rapidly absorbed,3 with steady-state concentrations achieved within 2 days4,5; its metabolism occurs primarily through glucuronidation.6 Al-though some drugs that induce the rele-vant enzyme, UDP glucuronosyltrans-ferase, may significantly reduce ralte-gravir concentrations,4,7 this does not apply to commonly used antiretroviral agents. Consequently, raltegravir metab-olism is usually unaffected by concomi-tant administration of nucleoside and nonnucleoside reverse transcriptase in-hibitors (NRTIs, NNRTIs) or protease inhibitors (PIs).8,9 Available data suggest some interindividual variability for ralte-gravir plasma concentrations. Yilmaz e