Abametapir and Lorlatinib: 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 recordLorlatinib
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 you only put it on your scalp, it can slow down a liver enzyme (called CYP3A4) that your body uses to break down other medicines. Lorlatinib (Lorbrena) is a cancer medicine that your body clears using that same enzyme.
So if you use abametapir, your body may not clear lorlatinib as fast, and the amount in your blood can climb higher than intended. That could mean more side effects. The good news is this is very manageable. Please talk with your pharmacist or oncologist before using any lice treatment, and they can plan the safest timing for you.
Effect: Increased lorlatinib exposure. Abametapir inhibits CYP3A4, and lorlatinib is a CYP3A4 substrate, so inhibition reduces its metabolism and raises AUC/Cmax, increasing toxicity risk.
- Direction: Increased lorlatinib effect/exposure (parent drug, not a prodrug).
- Onset: Rapid; enzyme inhibition can persist up to ~2 weeks after topical application.
- Evidence: Theoretical.
- Magnitude: Not quantified.
Management: Avoid CYP3A4 substrates such as lorlatinib within 2 weeks after abametapir application. If concurrent lice treatment is unavoidable, avoid abametapir and consider an alternative. Coordinate any decisions with the oncology team.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
For a period of 2 weeks following abametapir application, refrain from administering CYP3A4 substrates. Should avoiding these substrates not be practical, then abametapir itself should not be used1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
Keep taking your lorlatinib exactly as prescribed. The important step is not to add a lice treatment on your own.
- Tell your pharmacist and oncologist before using abametapir or any lice product.
- Because the enzyme-blocking effect can last about 2 weeks, your care team may recommend an alternative lice treatment rather than abametapir.
- If abametapir must be used, your team can plan timing and may monitor you more closely for extra lorlatinib side effects.
Ask your team which lice treatment is safest for you.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Lorlatinib together?
Abametapir can block the enzyme that clears lorlatinib, raising lorlatinib levels and side effect risk for up to about two weeks. Do not use abametapir with lorlatinib without checking with your oncologist or pharmacist, who can pick a safer lice treatment. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abametapir and Lorlatinib 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 Lorlatinib interaction managed?
Keep taking your lorlatinib exactly as prescribed. The important step is not to add a lice treatment on your own. Tell your pharmacist and oncologist before using abametapir or any lice product. Because the enzyme-blocking effect can last about 2 weeks, your care team may recommend an alternative lice treatment rather than abametapir. If abametapir must be used, your team can plan timing and may m… 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 Lorlatinib 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 Lorlatinib
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