Drug interactions
Atazanavir + Efavirenz
Severity: Major
Atazanavir and Efavirenz: major interaction.
Last updated Sources: US FDA label
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Efavirenz induces CYP3A4 and lowers atazanavir concentrations, which may cause virologic failure and resistance if atazanavir is not boosted. Boosted atazanavir needs a dose adjustment when given with efavirenz in treatment-naive patients.
What this interaction means in plain words
Atazanavir and Efavirenz can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Atazanavir belongs to Anti Virals; Efavirenz belongs to Anti Virals.
Why it happens
Efavirenz induces CYP3A4 and UGT1A1, increasing atazanavir clearance.
What to do
Do not use unboosted atazanavir with efavirenz. If combined, give atazanavir with ritonavir at the labeled adjusted dose in treatment-naive patients, and avoid the combination in treatment-experienced patients.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Efavirenz
- Cobimetinib + Efavirenz Contraindicated
- Dienogest / estradiol valerate + Efavirenz Contraindicated
- Dihydroergotamine intranasal + Efavirenz Contraindicated
- Dihydroergotamine + Efavirenz Contraindicated
- Doravirine + Efavirenz Contraindicated
- Efavirenz + Elbasvir / grazoprevir Contraindicated
Other interactions of Atazanavir
- Alfuzosin + Atazanavir Contraindicated
- Atazanavir + Avanafil Contraindicated
- Atazanavir + Dronedarone Contraindicated
- Atazanavir + Eletriptan Contraindicated
- Atazanavir + Eplerenone Contraindicated
- Atazanavir + Ergotamine Contraindicated
Frequently asked questions
Can I take Atazanavir with Efavirenz?
MediHelp rates the interaction as major. Atazanavir and Efavirenz can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Efavirenz induces CYP3A4 and lowers atazanavir concentrations, which may cause virologic failure and resistance if atazanavir is not boosted. Boosted atazanavir needs a dose adjustment when given with efavirenz in treatment-naive patients.
How serious is the interaction between Atazanavir and Efavirenz?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Do not use unboosted atazanavir with efavirenz. If combined, give atazanavir with ritonavir at the labeled adjusted dose in treatment-naive patients, and avoid the combination in treatment-experienced patients.
What other medicines interact with Efavirenz?
MediHelp also lists interactions of Efavirenz with, for example, Cobimetinib, Dienogest / estradiol valerate, Dihydroergotamine intranasal. The full list is on the Efavirenz page.
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