Abemaciclib and Pimozide: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 10, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Pimozide
No brand names on recordAbemaciclib
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.
Here's what's going on. Pimozide is a medicine your body clears using a liver enzyme. Abemaciclib (Verzenio) may slow that enzyme down. When that happens, pimozide can build up in your body more than expected, which can raise the chance of side effects like drowsiness, muscle stiffness, or effects on your heart rhythm.
The good news: this is a possible (theoretical) concern, not something proven to happen in everyone. Your care team can handle it by adjusting your dose if needed and watching you a little more closely. Keep taking both exactly as prescribed, and let your pharmacist or doctor know you take them together.
Effect: Potential increased pimozide exposure with elevated risk of pimozide-related adverse reactions (QT prolongation, extrapyramidal symptoms, sedation).
Mechanism: Pimozide is a CYP1A2 substrate; abemaciclib may inhibit CYP1A2-mediated metabolism, reducing pimozide clearance and increasing AUC/Cmax.
- Direction: increased pimozide effect (inhibition; neither agent is dependent on activation to be effective).
- Evidence: theoretical.
- Onset: unspecified.
- Severity: major, given pimozide's narrow margin and QT liability.
Management: Individualize pimozide dosing and monitor for toxicity; consider ECG monitoring for QT. Coordinate any dose changes with the prescriber.
What happens
Increased pimozide exposure and an increased risk of pimozide-related adverse reactions
Interaction Deep Dive
When pimozide, which is metabolized by CYP1A2, is given together with agents that inhibit CYP1A2, pimozide levels may rise, potentially raising the likelihood of adverse reactions associated with pimozide1.
Why it happens (mechanism)
Inhibition of CYP1A2-mediated metabolism of pimozide
How to manage this interaction
What your care team may do:
- Tailor and individualize your pimozide dose while you are on both medicines.
- Monitor you more closely for pimozide side effects, which may include heart rhythm checks (ECG), and watch for drowsiness or muscle stiffness.
What you should do:
- Keep taking both medicines as prescribed unless your doctor tells you otherwise.
- Tell your pharmacist and prescriber that you take these together so they can plan monitoring.
- Report new symptoms like a fast or irregular heartbeat, fainting, unusual stiffness, or heavy sedation right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abemaciclib and Pimozide together?
Abemaciclib may raise pimozide levels and side-effect risk, so keep taking both as prescribed but tell your care team, who can adjust the dose and monitor you (including your heart rhythm). Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abemaciclib 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 "unspecified". The timing of this interaction is not well characterized.
How is the Abemaciclib and Pimozide interaction managed?
What your care team may do: Tailor and individualize your pimozide dose while you are on both medicines. Monitor you more closely for pimozide side effects, which may include heart rhythm checks (ECG), and watch for drowsiness or muscle stiffness. What you should do: Keep taking both medicines as prescribed unless your doctor tells you otherwise. Tell your pharmacist and prescriber that you take t… 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 Abemaciclib 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: Pimozide oral tablet, pimozide oral tablet. Endo USA, Inc (per DailyMed), Malvern, PA, 2017. DailyMed
Keep reading about Pimozide
Keep reading about Abemaciclib
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