Are Hi Efavirenz Blood Levels Associated With CNS Side Effects?
Several posters discussed the pharmacokinetics of efavirenz in relation to central nervous system (CNS) toxicity and viral suppression; long term adverse effects with efavirenz were also assessed.4-6 Nunez et. al. reported that plasma efavirenz concentrations > 3.5 mcg/mL were more frequent among subjects with CNS toxicity (13/15) compared to controls (17/36; p=.02).4 This data is in agreement with that recently reported by Marzolini et. al. in which efavirenz concentrations > 4 mcg/mL were associated with CNS toxicity among 130 HIV-infected patients.7 The authors suggest that the data from the 15 patients presented here support the introduction of therapeutic drug monitoring (TDM) for efavirenz in clinical practice. While this may eventually prove to be true, substantiating ARV efficacy along with reduced CNS symptoms with efavirenz doses below 600 mg daily are necessary before efavirenz TDM can be routinely recommended. In contrast to the above findings, Fiske et. al. from Dupont Pha
