Fexinidazole and Abemaciclib: 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
Fexinidazole
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.
Let's talk about taking fexinidazole together with abemaciclib (Verzenio). Your body clears abemaciclib using a liver enzyme called CYP3A4. Fexinidazole can slow that enzyme down, so abemaciclib may build up higher than intended. With a cancer drug like abemaciclib, higher levels can mean more side effects, such as diarrhea, low blood counts, tiredness, or nausea.
The good news is this is a predicted concern, and your care team can manage it. Please don't stop or change either medicine on your own. Instead, let your pharmacist or oncologist know you take both so they can decide the safest plan for you.
Effect: Fexinidazole inhibits CYP3A4, which is the primary metabolic pathway for abemaciclib. This is expected to increase abemaciclib exposure (AUC/Cmax), raising the risk of concentration-dependent toxicities.
- Direction: Increased abemaciclib effect (abemaciclib is the affected substrate; it is an active drug, not a prodrug).
- Mechanism: CYP3A4 inhibition by fexinidazole.
- Evidence: Theoretical; magnitude not quantified. Onset unspecified.
- Toxicities to watch: diarrhea, neutropenia, hepatotoxicity, fatigue, ILD/pneumonitis.
- Management: Avoid concomitant use per labeling. If unavoidable, dose may be individualized and patient monitored more closely (CBC, LFTs, GI symptoms).
What happens
An increased CYP3A4 substrate exposure
Interaction Deep Dive
Because fexinidazole inhibits CYP3A4, giving it together with CYP3A4 substrates raises the concentrations of those substrate drugs, which heightens the likelihood of adverse reactions; for this reason, such concurrent use should be avoided1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by fexinidazole
How to manage this interaction
The documented guidance is to avoid using these two together when possible, because fexinidazole can raise abemaciclib levels and increase side effects.
- Keep taking both as prescribed unless your care team tells you otherwise. Do not adjust anything on your own.
- Make sure your oncologist and pharmacist know you take both drugs. They may choose an alternative, adjust the abemaciclib dose to fit your situation, or watch you more closely.
- Report side effects promptly, especially diarrhea, unusual tiredness, signs of infection (fever), or yellowing of the skin/eyes.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Fexinidazole and Abemaciclib together?
Fexinidazole can raise abemaciclib levels and increase its side effects, so this combination is generally avoided. Tell your oncologist and pharmacist you take both so they can pick the safest plan. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Fexinidazole and Abemaciclib 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 Fexinidazole and Abemaciclib interaction managed?
The documented guidance is to avoid using these two together when possible, because fexinidazole can raise abemaciclib levels and increase side effects. Keep taking both as prescribed unless your care team tells you otherwise. Do not adjust anything on your own. Make sure your oncologist and pharmacist know you take both drugs. They may choose an alternative, adjust the abemaciclib dose to fit you… 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 Fexinidazole or Abemaciclib 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: Fexinidazole oral tablets, fexinidazole oral tablets. sanofi-aventis US LLC (per FDA), Bridgewater, NJ, 2021. DailyMed
Keep reading about Fexinidazole
Keep reading about Abemaciclib
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major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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