Efavirenz
A non-nucleoside reverse transcriptase inhibitor for HIV-1, known for vivid dreams, dizziness and other nervous system effects.
Also called EFV (abbreviation).
Drug card
- How it works
- Binding a pocket beside the reverse transcriptase active site and distorting it
- Used for
- HIV-1 infection, with other antiretrovirals
- Known for
- Vivid or abnormal dreams
- Harm to the fetus in early pregnancy
- Its name
- -vir means an antiviral
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does efavirenz work?
Binds HIV-1 reverse transcriptase away from its active site and blocks it noncompetitively; it does not inhibit HIV-2 or human DNA polymerases. It induces CYP3A and CYP2B6, speeding its own metabolism and that of other drugs. HIV becomes resistant quickly, most often through the K103N mutation.
Uses
What is efavirenz used for?
- HIV-1 infection, with other antiretrovirals
Side effects
Side effects of efavirenz
- Vivid or abnormal dreamsKnown for
- Harm to the fetus in early pregnancyKnown forSerious
- Dizziness and poor concentration
- Trouble sleeping (insomnia)
- Rash, usually in the first 2 weeks
- Severe depression and suicidal thoughtsSerious
- Psychosis, paranoia or maniaSerious
- Liver injury, rarely liver failureSerious
- Long QT intervalSerious
- SeizuresSerious
- Raised cholesterol and triglycerides
- Breast enlargement in men
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Take on an empty stomach, preferably at bedtime: food raises its levels and side effects, and bedtime eases the nervous system effects.
- Avoid in the first trimester of pregnancy.
- Many interactions through CYP3A and CYP2B6; contraindicated with elbasvir-grazoprevir.
- Consider other drugs in people at risk of torsades or on QT-prolonging drugs; check liver tests in hepatitis B or C.
Good to know: WHO has preferred dolutegravir to efavirenz since 2019, partly because HIV resistance to efavirenz and nevirapine is rising.
Remember it
A way to remember it
NRTIs fill the slot; NNRTIs jam the hinge.
NRTIs enter the active site as false nucleotides and end the DNA chain. NNRTIs bind a nearby pocket and twist the enzyme so it cannot work, and a single change in that pocket can make HIV resistant.
Written for biofideX
Its name
-vir means antiviral
Sub-stems name the target: -ciclovir, -amivir, -fovir, -tegravir, -navir, -buvir, -virine (NNRTIs). Lamivudine and zidovudine are antivirals without it.
- Every drug name stem
Its class
Non-nucleoside reverse transcriptase inhibitors
NNRTIs do not resemble nucleosides. They bind a pocket of HIV-1 reverse transcriptase next to, not in, the active site, which distorts the enzyme and blocks it noncompetitively, so HIV cannot copy its RNA into DNA. They do not act on HIV-2. Resistance comes fast, often through one change in that pocket such as K103N, and can cross between NNRTIs.
Easily mixed up with nucleoside reverse transcriptase inhibitors.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Efavirenz tablets: label (DailyMed)
- Efavirenz (NCI Thesaurus)
- WHO recommends dolutegravir as preferred HIV treatment option in all populations (WHO)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Antivirals
Efavirenz is one of 10 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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