Sustiva (efavirenz) is a non-nucleoside reverse transcriptase inhibitor (NNRTI). Like the other NNRTIs – which include Viramune® (nevirapine) and Rescriptor® (delavirdine) – Sustiva blocks HIV's reverse transcriptase enzyme, a protein that helps the virus invade the DNA inside human cells. (Click here to learn more about the life cycle of HIV and the ways in which NNRTIs and other anti-HIV drugs work).
An anti-HIV drug regimen consisting of Sustiva and two regular nucleoside
analogues (e.g., AZT and 3TC) is a popular
option for HIV-positive people starting therapy for the first time. Sustiva
only needs to be taken once a day, preferably on an empty stomach, usually
at bedtime.
As discussed in the our lesson, "When Should I Start Treatment, and What Should I Take First?", Sustiva is the only NNRTI recommended as a preferred choice by the United States Public Health Service (USPHS) – the federal agency responsible for setting health-related policies in the U.S. – for patients who have never been on anti-HIV therapy before (the others are recommended as "alternative" options) . This is because Sustiva has been shown to be associated with long-term benefits in people who have both low and high (>100,000 copies/mL) viral loads before starting therapy. While some protease inhibitors (PIs) are also recommended by the USPHS for patients starting therapy for the first time, Sustiva may not cause some of the long-term side effects being seen in some people taking PIs, such as abnormal body fat changes (lipodystrophy).