Antiretroviral, non-nucleoside reverse transcriptase inhibitor (NNRTI)
ATC code: J05AG03 (Efavirenz)
Brand names
Sustiva, Atripla
Binds the allosteric pocket of HIV-1 reverse transcriptase and blocks its activity. Not active against HIV-2 or other retroviruses. Strong inducer of CYP3A4 and CYP2B6 (also a CYP2B6 substrate). Reduces levels of most co-administered drugs. Main adverse profile is neuropsychiatric (insomnia, vivid dreams, depression).
Second line
Efavirenz is a second-line NNRTI in HIV-1 antiretroviral therapy. GeSIDA 2024 places it as an option when first-line integrase inhibitors are unavailable. Usually taken in the evening before sleep to minimise neuropsychiatric adverse effects. In women of childbearing age – discuss contraception and risk of CNS defects in the first trimester.
3 pairs found. Sorted from critical to minor.
Mechanism
Efavirenz induces CYP3A4 and P-gp. Apixaban falls 50% – stroke risk in AF.
Symptoms
Ischemic stroke or recurrent VTE.
Management
Alternative ARV – dolutegravir, or alternative anticoagulant – warfarin with INR 2.5-3.5.
Mechanism
St. John's wort is a potent inducer of the CYP3A4 enzyme (and of CYP2C9 and P-glycoprotein). After 1–2 weeks it speeds up the breakdown of Efavirenz and lowers its blood level, weakening its effect.
Symptoms
Fall in antiretroviral levels, loss of HIV virological control and risk of drug resistance.
Management
Contraindicated with antiretroviral therapy. Do not use St. John's wort during HIV treatment.
Mechanism
Efavirenz induces CYP3A4. Simvastatin falls 60% – lipid-lowering effect lost.
Symptoms
returns to baseline.
Management
Alternative statin – pravastatin or rosuvastatin.
Opens the checker prefilled with this drug. Pick the second one from your regimen.
Neural tube defects reported with first-trimester exposure. Switch to non-efavirenz regimen when planning pregnancy if possible.
Breastfeeding by HIV-positive women not recommended in Spain.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Efavirenz is evaluated for the following indications with varying evidence strength: HIV infection (evidence tier B). See the full indication matrix with dosing and citations above on this page.
Common side effects of Efavirenz (≥ 1 in 100): Insomnia, Vivid dreams, Dizziness, Rash, Transaminase rise, Hyperlipidaemia. See the Safety section for uncommon and serious reactions.
FDA category D. Neural tube defects reported with first-trimester exposure. Switch to non-efavirenz regimen when planning pregnancy if possible.
Breastfeeding by HIV-positive women not recommended in Spain.
Efavirenz is contraindicated in: Pimozide, oral midazolam, ergotamine, cisapride; St John's wort (loss of ARV effect); Severe hepatic impairment; Depression with prior suicidal ideation. Full list in the Safety section.