Abametapir and Tucatinib: 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 recordTucatinib
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, and Tucatinib (Tukysa) is a cancer medicine. Even though abametapir is applied to your scalp, a small amount can get into your body and slow down a liver enzyme (called CYP3A4) that normally helps break down tucatinib.
When that enzyme is blocked, tucatinib can build up higher than expected, which may raise your chance of side effects. This effect can last for about two weeks after using the lice treatment. The good news is that this is easy to plan around. Talk with your pharmacist or cancer care team before using any lice product so they can help you time things safely.
Mechanism: Abametapir inhibits CYP3A4. Tucatinib is a CYP3A4 substrate, so co-exposure is predicted to raise tucatinib AUC/Cmax, increasing toxicity risk. Neither is a prodrug requiring activation, so the effect is straightforwardly additive to tucatinib exposure.
- Direction: increased tucatinib exposure (increases_drug_effect)
- Onset: rapid; enzyme inhibition may persist ~2 weeks post-application
- Evidence: theoretical
- Severity: major
Management: Avoid CYP3A4 substrates, including tucatinib, within 2 weeks of abametapir application. If concurrent tucatinib therapy cannot be interrupted, avoid abametapir and select an alternative lice treatment. Coordinate through oncology.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
Do not administer CYP3A4 substrates during the 2-week period following application of abametapir. When avoiding these substrates is not possible, abametapir itself should be avoided 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
Keep taking your tucatinib (Tukysa) exactly as prescribed. The concern is with the head lice lotion, not your cancer medicine.
- Do not start any product containing abametapir without checking with your oncology team or pharmacist first.
- Because the interaction can last about two weeks after the lotion is applied, timing matters, so your care team may advise avoiding abametapir while you are on tucatinib.
- Ask your pharmacist about safe alternative lice treatments that do not affect your cancer medicine.
Bring up any new medicines, lotions, or over-the-counter products so your team can keep you safe.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Tucatinib together?
Abametapir can raise tucatinib levels and increase side-effect risk for up to two weeks, so avoid using them together and ask your pharmacist about a lice treatment that is safe with your cancer medicine. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abametapir and Tucatinib 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 Tucatinib interaction managed?
Keep taking your tucatinib (Tukysa) exactly as prescribed. The concern is with the head lice lotion, not your cancer medicine. Do not start any product containing abametapir without checking with your oncology team or pharmacist first. Because the interaction can last about two weeks after the lotion is applied, timing matters, so your care team may advise avoiding abametapir while you are on tuca… 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 Tucatinib 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 Tucatinib
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