Abametapir and Vinblastine: 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 recordVinblastine
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 put it on your scalp, a little gets into your body, where it can block a liver enzyme called CYP3A4. That same enzyme is one of the main ways your body breaks down vinblastine, a chemotherapy drug.
If the enzyme is blocked, vinblastine can build up higher than intended. That could mean stronger side effects, like a bigger drop in blood counts or more nerve and stomach problems. This is a serious combination, so please let your cancer team and pharmacist know before using any lice treatment. They can help you time things safely or pick another option.
Mechanism: Abametapir inhibits CYP3A4. Vinblastine is a CYP3A4 substrate (not a prodrug), so inhibition reduces its metabolism and increases systemic exposure (AUC/Cmax).
Direction: Increased vinblastine exposure, raising risk of dose-dependent toxicity (myelosuppression, neurotoxicity, GI toxicity).
- Onset: rapid
- Severity: major
- Evidence: theoretical (based on abametapir's known CYP3A4 inhibition)
Management: Avoid CYP3A4 substrates, including vinblastine, within 2 weeks after abametapir application. If concurrent use is unavoidable, avoid abametapir. Consider alternative lice therapy and closer monitoring of counts and toxicity if exposure occurs.
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
Do not administer CYP3A4 substrates during the 2 week period following abametapir application. Where avoiding this is not possible, abametapir should not be used1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
The safest approach here is separation and avoidance, and your care team can arrange this.
- Do not start or stop anything on your own. Tell your oncology team and pharmacist that abametapir (a lice lotion) has been prescribed or is being considered.
- Guidance on file is to avoid CYP3A4 substrates like vinblastine for 2 weeks after applying abametapir.
- If that timing is not workable, the team may choose a different lice treatment instead.
- If both are used, expect closer monitoring (such as blood counts and watching for side effects).
Keep taking your prescribed chemotherapy as directed and raise any lice-treatment plans with your team first.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Vinblastine together?
Abametapir can raise vinblastine levels and increase its toxicity, so avoid vinblastine (and other CYP3A4 drugs) for 2 weeks after using abametapir, or choose a different lice treatment. Always coordinate with your oncology team and pharmacist first. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abametapir and Vinblastine 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 Vinblastine interaction managed?
The safest approach here is separation and avoidance, and your care team can arrange this. Do not start or stop anything on your own. Tell your oncology team and pharmacist that abametapir (a lice lotion) has been prescribed or is being considered. Guidance on file is to avoid CYP3A4 substrates like vinblastine for 2 weeks after applying abametapir. If that timing is not workable, the team may cho… 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 Vinblastine 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 Vinblastine
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