Drug interactions
Efavirenz + Enzalutamide
Severity: Major
Efavirenz and Enzalutamide: major interaction.
Last updated
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
Enzalutamide is a strong CYP3A4 inducer and may substantially lower efavirenz concentrations, risking virologic failure. Efavirenz, a CYP3A4 inducer, may reduce enzalutamide exposure, though the net active moiety effect is smaller.
What this interaction means in plain words
Efavirenz and Enzalutamide 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 belongs to Anti Virals; Enzalutamide belongs to Endocrine.
Why it happens
Mutual CYP3A4 induction, with enzalutamide also inducing CYP2B6, increasing clearance of both drugs.
What to do
Avoid the combination where possible and choose an antiretroviral less affected by induction. If used, monitor HIV viral load and efavirenz levels, and watch for reduced enzalutamide efficacy.
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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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 Enzalutamide
- Doravirine + Enzalutamide Contraindicated
- Elbasvir / grazoprevir + Enzalutamide Contraindicated
- Ensitrelvir + Enzalutamide Contraindicated
- Enzalutamide + Fostemsavir Contraindicated
- Enzalutamide + Isavuconazonium Contraindicated
- Enzalutamide + Lenacapavir Contraindicated
Frequently asked questions
Can I take Efavirenz with Enzalutamide?
MediHelp rates the interaction as major. Efavirenz and Enzalutamide 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. Enzalutamide is a strong CYP3A4 inducer and may substantially lower efavirenz concentrations, risking virologic failure. Efavirenz, a CYP3A4 inducer, may reduce enzalutamide exposure, though the net active moiety effect is smaller.
How serious is the interaction between Efavirenz and Enzalutamide?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination where possible and choose an antiretroviral less affected by induction. If used, monitor HIV viral load and efavirenz levels, and watch for reduced enzalutamide efficacy.
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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