ABSTRACT
Efavirenz is a widely used agent for treatment of HIV-1 infection and is a member of the class of nonnucleoside reverse transcriptase inhibitors. When administered in combination with other antiretroviral drugs, it suppresses HIV-1 replication, improves immunologic function, enhances quality of life, and reduces HIV-related clinical progression and mortality; when HIV replication is fully suppressed it prevents onward HIV transmission. Efavirenz, in combination with other antiretroviral agents, is still recommended as a preferred agent for initial treatment of HIV-1 infection in World Health Organization (WHO) guidelines but the availability of more effective and better tolerated antiretroviral agents means that it is now listed as an alternative rather than a preferred agent in US, European, and UK guidelines (World Health Organization, 2013; Gunthard et al., 2014; British HIV Association, 2015; European AIDS Clinical Society Guidelines Panel, 2015; Panel on Antiretroviral Guidelines for Adults and Adolescents, 2015). The main advantages of efavirenz are its potency, convenient dosing (once daily), tolerability, and established track record; its chief drawbacks are low genetic barrier to resistance (with cross-resistance to most of the other nonnucleoside agents) if administered as part of an insufficiently potent regimen, neuropsychiatric side effects, and its potential contribution to lipodystrophy and metabolic syndrome. Lack of established safety in pregnancy was an earlier concern but with accumulating clinical observations of safe use in humans and risk–benefit considerations, efavirenz is no longer contraindicated in pregnancy (see section 6d, Fetal toxicity).
