Abametapir and Pimozide: 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 recordPimozide
No brand names on record
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. After it's applied, it can block a liver enzyme (called CYP3A4) that normally helps your body break down other medicines. Pimozide is one of those medicines. If your body can't clear pimozide well, its levels can climb higher than intended.
That matters because higher pimozide levels can affect your heart rhythm. The good news is this is easy to manage. Your care team may space these medicines apart in time or pick a different plan. Please don't change anything on your own, just check with your pharmacist or doctor first.
Mechanism: Abametapir inhibits CYP3A4, reducing metabolism of pimozide (a CYP3A4 substrate), which increases pimozide exposure (AUC/Cmax). Neither agent is a prodrug here, so this is a straightforward increase in pimozide effect.
- Direction: increased pimozide exposure and effect
- Clinical concern: pimozide is a QT-prolonging agent; elevated levels raise risk of QTc prolongation and arrhythmia
- Onset: rapid; inhibition can persist for up to 2 weeks post-application
- Evidence: theoretical
- Management: avoid CYP3A4 substrates for 2 weeks after abametapir; if unavoidable, avoid abametapir
What happens
Increased exposure of CYP3A4 substrate
Interaction Deep Dive
Within a 2 week window following the application of abametapir, the concurrent use of CYP3A4 substrates should be avoided. Should this not be possible, abametapir itself should not be used 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by abametapir
How to manage this interaction
Here's how a care team typically handles this:
- Timing/avoidance: The guidance is to avoid CYP3A4 substrates like pimozide for 2 weeks after applying abametapir. If that isn't feasible, the abametapir treatment is avoided instead.
- Closer monitoring: If both are needed, your team may watch you more closely.
What you should do: Keep taking your medicines as prescribed and don't stop anything on your own. Tell your pharmacist or prescriber you use pimozide before starting abametapir so they can plan the safest timing for you.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abametapir and Pimozide together?
Abametapir can raise pimozide levels by blocking its breakdown for up to two weeks, which is a concern for pimozide's heart-rhythm effects; ask your pharmacist or doctor to plan the timing before using both. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abametapir and Pimozide 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 Pimozide interaction managed?
Here's how a care team typically handles this: Timing/avoidance: The guidance is to avoid CYP3A4 substrates like pimozide for 2 weeks after applying abametapir. If that isn't feasible, the abametapir treatment is avoided instead. Closer monitoring: If both are needed, your team may watch you more closely. What you should do: Keep taking your medicines as prescribed and don't stop anything on your… 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 Pimozide 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 Pimozide
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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