Abametapir and Pemigatinib: 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 recordPemigatinib
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 to treat head lice. Even though it's applied to the scalp, some of it gets into your body and can block a liver enzyme called CYP3A4 for up to two weeks. Your cancer medicine, pemigatinib (Pemazyre), is broken down by that same enzyme.
When abametapir slows down the enzyme, pemigatinib can build up to higher levels than intended, which may raise the risk of side effects. The good news is this is easy to plan around. Talk with your pharmacist or oncologist before using any lice treatment so your care team can protect you.
Mechanism: Abametapir inhibits CYP3A4. Pemigatinib is a CYP3A4 substrate, so co-exposure is expected to increase pemigatinib AUC/Cmax, raising toxicity risk (neither drug is affected by prodrug considerations here).
- Direction: Increased pemigatinib exposure and effect.
- Onset: Rapid; inhibition can persist ~2 weeks after a single topical application.
- Evidence: Theoretical, but rated major.
- Management: Avoid CYP3A4 substrates, including pemigatinib, for 2 weeks after abametapir. If concurrent use is unavoidable, avoid abametapir. If exposure occurs, consider closer monitoring for pemigatinib toxicity per prescribing guidance.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
Do not administer CYP3A4 substrates during the 2-week period following application of abametapir. Should this be impractical, abametapir itself should not be used 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
Keep taking your pemigatinib (Pemazyre) exactly as prescribed. The key is to avoid using abametapir lice lotion during and for about two weeks after treatment, because its effect on the liver enzyme lingers.
- Tell your pharmacist and oncologist before using any lice product, prescription or over-the-counter.
- Your care team may choose a different lice treatment, or time things so the two don't overlap.
- If abametapir was already used, your team may monitor you more closely for pemigatinib side effects.
Don't start, stop, or change either medicine on your own; let your care team make that call.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Pemigatinib together?
Abametapir can raise pemigatinib levels for up to two weeks by blocking CYP3A4, so avoid combining them and ask your care team to pick a safer lice treatment or timing. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abametapir and Pemigatinib 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 Pemigatinib interaction managed?
Keep taking your pemigatinib (Pemazyre) exactly as prescribed. The key is to avoid using abametapir lice lotion during and for about two weeks after treatment, because its effect on the liver enzyme lingers. Tell your pharmacist and oncologist before using any lice product, prescription or over-the-counter. Your care team may choose a different lice treatment, or time things so the two don't overl… 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 Pemigatinib 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 Pemigatinib
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