Switch from Enfuvirtide to Raltegravir Lowers Plasma Concentrations

We compared tipranavir and darunavir concentrations measured at steady state in 20 human immunodeficiency virus (HIV)-infected patients enrolled in the EASIER-ANRS 138 clinical trial who switched from enfuvirtide to raltegravir while maintaining the same background regimen. The geometric mean ratios of the observed predose concentration (Ctrough), maximum concentration of drug observed in plasma (Cmax), and area under the plasma concentration-time curve (AUC) before (day 0) and after (week 24) the switch were 0.49, 0.76, and 0.67 and 0.82, 0.68, and 0.64 for tipranavir and darunavir, respectively. The virologic consequences of these drug interactions have yet to be determined. Among patients with multidrug-resistant human immunode-ficiency virus type 1 (HIV-1) infection, salvage antiretroviral regimens, including enfuvirtide, have demonstrated sustained efficacy. Nowadays, reluctance to use subcutaneous injections supports the replacement of enfuvirtide with newly available antiretrovirals, such as raltegravir, an integrase inhibitor ad-ministered orally. The EASIER-ANRS 138 clinical trial dem-onstrated that a switch to raltegravir was safe, well tolerated