Tazemetostat and Abametapir: 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 recordTazemetostat
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's applied to the skin, a little gets into your body and can temporarily block an important liver enzyme called CYP3A4. That enzyme is one of the main ways your body breaks down tazemetostat (Tazverik), your cancer medicine.
When that enzyme is slowed down, more tazemetostat can build up in your body than expected, which could raise the risk of side effects. This is based on how the drugs work rather than on patient reports, but it's taken seriously. The good news is your care team can plan the timing so both medicines are used safely. Please check with your pharmacist or doctor before using both.
Mechanism: Abametapir is a CYP3A4 inhibitor; tazemetostat is a CYP3A4 substrate. Concurrent use is predicted to reduce tazemetostat clearance, increasing its exposure (AUC/Cmax) and the potential for concentration-related toxicity.
- Direction: increased tazemetostat exposure (neither drug is a prodrug requiring activation).
- Onset: rapid; inhibition can persist due to abametapir's prolonged CYP3A4 effect.
- Evidence: theoretical (mechanism-based).
- Magnitude: not quantified.
Management: Avoid CYP3A4 substrates, including tazemetostat, for 2 weeks after abametapir application. If tazemetostat cannot be interrupted, avoid using abametapir and consider an alternative lice treatment. Enhanced monitoring for tazemetostat toxicity is warranted if co-exposure occurs.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
For a period of 2 weeks following abametapir application, refrain from using substrates of CYP3A4. Should avoiding these substrates not be possible, then abametapir itself should be avoided1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
The main strategy here is separation and timing, coordinated by your care team.
- Keep taking your tazemetostat (Tazverik) exactly as prescribed. Do not stop or change it on your own.
- Guidance is to avoid CYP3A4 substrates like tazemetostat for 2 weeks after applying abametapir lotion. If you cannot pause tazemetostat, the abametapir lice treatment should be avoided instead.
- Tell your pharmacist and oncologist before using any lice product so they can pick the safest option or timing.
- If both were used together, your team may watch you more closely for increased tazemetostat side effects.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Tazemetostat and Abametapir together?
Abametapir can raise tazemetostat levels by blocking CYP3A4, so avoid tazemetostat for 2 weeks after applying abametapir; if that isn't possible, avoid the abametapir and ask your care team about a different lice treatment. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Tazemetostat and Abametapir 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 Tazemetostat and Abametapir interaction managed?
The main strategy here is separation and timing, coordinated by your care team. Keep taking your tazemetostat (Tazverik) exactly as prescribed. Do not stop or change it on your own. Guidance is to avoid CYP3A4 substrates like tazemetostat for 2 weeks after applying abametapir lotion. If you cannot pause tazemetostat, the abametapir lice treatment should be avoided instead. Tell your pharmacist and… 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 Tazemetostat or Abametapir 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 Tazemetostat
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