Would a CYP2B6 Test Help HIV Patients Being Treated With Efavirenz?

Abstract

Efavirenz is a potent and effective nonnucleoside reverse transcriptase inhibitor that is a preferred component of first-line antiretroviral therapy (ART) for HIV-1-infected individuals in both wealthy and resource-limited countries [1,2]. The use of efavirenz in clinical practice has further increased in recent years, especially in developing countries. It is usually prescribed at a fixed dosage of 600 mg once daily. Some patients who receive efavirenz have experienced adverse effects such as neuropsychiatric manifestations, skin rash, hepatitis and dyslipidemia [1,3]. In clinical practice, concern over neuro psychiatric adverse effects often plays a role in the decision of whether or not to include efavirenz as part of ART. Prediction of therapeutic efficacy and the likelihood of developing psychiatric disorders have been associated with plasma efavirenz concentrations [4]. The preferable mid-dosing plasma level of efavirenz is 1000–4000 ng/ml to allow for optimized antiretroviral potency and to minimize the risk of neuropsychiatric toxicity. HIV-1-infected patients who receive standarddose efavirenz and have plasma efavirenz concentration of 4000 ng/ml may experience adverse CNS effects more frequently [4]. Many studies have highlighted the potential for serious psychiatric complications with efavirenz, including depression, psychosis, amnesia, extreme excitability, aggressive behavior, post-traumatic stress disorder symptoms and induced suicidal effect [3,4]. However, increased neuropsychiatric adverse effects were typically reported only during the first month after starting this medication [4–6]. Clinical trials have reported CNS side effects in >50% of