Effect of body weight and composition on efavirenz, atazanavir or darunavir concentration.

Background: To compare the steady state plasma concentrations (Css) of three antiretroviral drugs in both normal and overweight patients, and to determine the relationship between Css and fat mass (FM) or lean body mass.

Methods: Patients treated for more than 6 months once daily with one of the antiretroviral drugs: efavirenz (EFV) 600mg, atazanavir boosted with ritonavir (ATV-r) 300mg/100mg, or darunavir boosted with ritonavir (DRV-r) 800mg/100mg, combined with two nucleoside analogues, were enrolled prospectively. One at steady state, plasma samples for the assessment of drug concentration were taken and body composition was assessed by bioelectrical impedance.