Efavirenz
Efavirenz (Sustiva) is an antiretroviral medicine used, together with other antiretrovirals, to treat HIV-1 infection. It is listed for Viraday, Trustiva and Sustiva, three tablet brands built around it.
Key points
- In vitro studies suggest two liver enzymes, CYP3A and CYP2B6, are chiefly responsible for breaking efavirenz down, and efavirenz itself makes these enzymes more active, increasing the breakdown of other medicines processed the same way.
- Sustiva contains efavirenz on its own, while Viraday and Trustiva combine it with tenofovir disoproxil and emtricitabine in one tablet.
- In controlled trials of 1,008 patients treated with efavirenz tablets, central nervous system symptoms were reported, including dizziness in 28.1%, insomnia in 16.3%, impaired concentration in 8.3%, somnolence in 7.0%, abnormal dreams in 6.2% and hallucinations in 1.2%.
What Efavirenz is used for
Efavirenz tablets are used, together with other antiretroviral medicines, to treat HIV-1 infection in adults and in children from 3 months old who weigh at least 3.5kg. In this catalogue, efavirenz is grouped under HIV Management.
Common questions about Efavirenz
Can Sustiva be used on its own to treat HIV?
No. Efavirenz tablets must not be used as a single medicine to treat HIV-1 infection, or added alone to a failing regimen. Resistant virus emerges rapidly when efavirenz is used as the only antiretroviral medicine, which is why Sustiva is meant to be paired with others rather than taken by itself.
Does efavirenz affect heart rhythm?
Efavirenz has been linked to QTc prolongation, a change in the heart’s electrical rhythm. Doctors may consider alternatives when it would be combined with a medicine known to carry a risk of Torsade de Pointes, a dangerous irregular heartbeat, or for patients who are already at higher risk of this problem.
What does an efavirenz rash look like?
Rashes linked to efavirenz are usually mild to moderate skin eruptions that start within the first two weeks of treatment, with a median onset of 11 days, and resolve within a month for most patients who continue, with a median duration of 16 days. A smaller number of patients, 0.9%, develop more severe reactions with blistering or ulceration.
Are there psychiatric side effects with efavirenz?
Serious psychiatric adverse experiences have been reported in patients treated with efavirenz tablets, separate from the central nervous system symptoms such as dizziness, insomnia, impaired concentration and vivid dreams also seen in clinical trials.