Efavirenz (Sustiva®) is a first-generation non-
nucleoside reverse transcriptase inhibitor (NNRTI) used to treat human immunodeficiency virus (HIV) type 1
infection or to prevent the spread of HIV. In 1998, the FDA authorized
efavirenz for the treatment of HIV-1
infection. Patients formerly required three 200 mg
efavirenz capsules daily, which was rapidly updated to a 600 mg
tablet that only required one
tablet per day. However, when given 600 mg once daily, plasma
efavirenz concentrations were linked not only to poor HIV suppression but also to toxicity. Clinical data suggested that the standard dose of
efavirenz could be reduced without compromising its effectiveness, resulting in a reduction in side effects and making the
drug more affordable. Therefore, ENCORE1 was performed to compare the efficiency and safeness of a reduced dose of
efavirenz (400 mg) with the standard dose (600 mg) plus two NRTI in antiretroviral-naïve HIV-infected individuals. Nowadays, due to the emergence of
integrase strand transfer inhibitors (INSTIs), some consider that it is time to stop using
efavirenz as a first-line treatment on a global scale, in the parts of the world where that is possible.
Efavirenz has been a primary first-line
antiviral drug for more than 15 years. However, at this moment, the best use for
efavirenz could be for pre-exposure prophylaxis (PrEP) and repurposing in medicine.