Abemaciclib and Carbamazepine: 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
Carbamazepine
Abemaciclib
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. Carbamazepine (Tegretol) speeds up an enzyme in your liver called CYP3A4. That same enzyme breaks down your cancer medicine, abemaciclib (Verzenio). So when you take both, your body clears the abemaciclib faster and its blood levels can drop. In one study with a similar strong booster of this enzyme, abemaciclib levels fell by about two-thirds.
The worry here isn't extra side effects. It's that too little abemaciclib may not fight the cancer as well as it should. The good news is your care team can plan around this, often by choosing a different medicine that doesn't cause this problem. Please don't change anything on your own. Just let your oncologist or pharmacist know you take both.
Mechanism: Carbamazepine is a strong CYP3A4 inducer; abemaciclib is a CYP3A4 substrate. Induction accelerates abemaciclib metabolism, lowering plasma concentrations of the parent drug and its active metabolites.
Direction / magnitude: Reduced abemaciclib exposure with potential loss of antineoplastic efficacy. A strong inducer (rifampin) decreased abemaciclib AUC by ~67%; a comparable effect is expected with carbamazepine.
- Evidence: theoretical (extrapolated from rifampin data)
- Onset: unspecified; induction typically develops over days to weeks
- Management: Avoid coadministration. Select an alternative anticonvulsant that does not induce CYP3A4. If an inducer is unavoidable, dosing should be individualized by the care team.
What happens
Decreased abemaciclib plasma concentration
Interaction Deep Dive
Taking abemaciclib together with a potent CYP3A4 inducer can lower the plasma concentrations of both abemaciclib and its active metabolite, potentially reducing therapeutic effectiveness. Research showed that giving rifampin, a strong CYP3A4 inducer, alongside abemaciclib reduced abemaciclib exposure by 67%. This combination should be avoided, and alternative agents should be considered1.
Why it happens (mechanism)
Induction of CYP3A4-mediated abemaciclib metabolism
How to manage this interaction
What your care team may do:
- Try to avoid using these two together, since combining them can lower how much abemaciclib is in your body.
- Choose an alternative medicine (for example, a seizure or mood drug that does not speed up this liver enzyme) so your cancer treatment keeps working as intended.
- Individualize and monitor your therapy closely if both must be used.
What you should do: Keep taking both exactly as prescribed for now, and do not stop or change either one on your own. Tell your oncologist and pharmacist that you take both so they can review the best option for you.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In drug interaction trials conducted in healthy volunteers, giving a single 200 mg dose of abemaciclib together with rifampin 600 mg daily (a potent CYP3A inducer) reduced the AUC(0 to infinity) of abemaciclib along with its active metabolites (M2, M18, and M20) by 67% 1.
Common questions
Can I take Abemaciclib and Carbamazepine together?
Carbamazepine can lower abemaciclib levels and may weaken its cancer-fighting effect, so this combination is usually avoided. Talk with your oncologist or pharmacist about a safer alternative before changing anything. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abemaciclib and Carbamazepine 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 Carbamazepine interaction managed?
What your care team may do: Try to avoid using these two together, since combining them can lower how much abemaciclib is in your body. Choose an alternative medicine (for example, a seizure or mood drug that does not speed up this liver enzyme) so your cancer treatment keeps working as intended. Individualize and monitor your therapy closely if both must be used. What you should do: Keep taking b… 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.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Abemaciclib or Carbamazepine 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: VERZENIO(TM) oral tablets, abemaciclib oral tablets. Lilly USA LLC (per FDA), Indianapolis, IN, 2017. DailyMed
Keep reading about Carbamazepine
Keep reading about Abemaciclib
These medications also interact with supplements
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist