Abametapir and Enzalutamide: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jun 30, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Abametapir
No brand names on recordEnzalutamide
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
Abametapir is a lotion used on the scalp to treat head lice. Even though it goes on your skin, some of it can get into your body and briefly block a liver enzyme called CYP3A4. That enzyme is one of the main ways your body clears enzalutamide (Xtandi), your prostate cancer medicine.
When that enzyme is slowed, more enzalutamide can build up in your body, which could raise your chance of side effects. This warning is based mostly on how the drugs work rather than on real reports, but it is still worth taking seriously. Please talk with your pharmacist or doctor before using a lice treatment so they can help you plan the timing safely.
Mechanism: Abametapir inhibits CYP3A4. Enzalutamide is a CYP3A4 substrate (and itself a strong CYP3A4 inducer), so abametapir exposure may transiently reduce enzalutamide clearance, increasing its exposure (AUC/Cmax) and toxicity risk.
- Direction: increased enzalutamide exposure (neither drug is a prodrug requiring 3A4 activation here).
- Onset: rapid.
- Evidence: theoretical.
- Severity: major.
Management: Avoid CYP3A4 substrates for 2 weeks after abametapir application; if unavoidable, avoid abametapir. If co-exposure occurs, monitor for enzalutamide-related adverse effects (fatigue, hypertension, seizure risk) and individualize care.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
For a period of 2 weeks following abametapir application, do not use CYP3A4 substrates. Should this prove impractical, abametapir itself should be avoided 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
Your care team can manage this easily with timing.
- Keep taking your enzalutamide (Xtandi) as prescribed. Do not stop or change it on your own.
- The guidance is to avoid CYP3A4 medicines like enzalutamide for 2 weeks after applying abametapir lice lotion. If that spacing is not possible, the alternative is to avoid using abametapir.
- Before using any lice treatment, ask your pharmacist or prescriber which option and timing is safest for you.
- If you have already used both close together, watch for increased side effects and let your care team know so they can monitor you more closely.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Enzalutamide together?
Abametapir can briefly raise enzalutamide levels by blocking CYP3A4, so avoid enzalutamide for 2 weeks after using this lice lotion, or skip the lotion; check timing with your pharmacist first. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abametapir and Enzalutamide interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How is the Abametapir and Enzalutamide interaction managed?
Your care team can manage this easily with timing. Keep taking your enzalutamide (Xtandi) as prescribed. Do not stop or change it on your own. The guidance is to avoid CYP3A4 medicines like enzalutamide for 2 weeks after applying abametapir lice lotion. If that spacing is not possible, the alternative is to avoid using abametapir. Before using any lice treatment, ask your pharmacist or prescriber… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Abametapir or Enzalutamide need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- Product Information: XEGLYZE(TM) topical lotion, abametapir topical lotion. Dr Reddy’s Laboratories Inc (per FDA), Princeton, NJ, 2020. DailyMed
Keep reading about Abametapir
Keep reading about Enzalutamide
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