Abemaciclib and Voriconazole: 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
Voriconazole
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. Voriconazole (Vfend) is a strong antifungal that slows down a liver enzyme called CYP3A4. That same enzyme is what your body uses to break down abemaciclib (Verzenio). So when you take them together, abemaciclib can build up higher than usual in your blood.
Higher levels can mean more side effects, like diarrhea, nausea, tiredness, or lower blood counts. The good news is this is very manageable. Your care team can lower your abemaciclib dose while you're on the antifungal and adjust it back afterward. Please don't change anything on your own, just talk with your oncology team or pharmacist so they can tailor your dose safely.
Mechanism: Voriconazole is a strong CYP3A4 inhibitor; abemaciclib is a CYP3A4 substrate (active parent plus active metabolites). Inhibition reduces metabolic clearance, increasing abemaciclib exposure (AUC/Cmax) and potential toxicity (diarrhea, neutropenia, hepatotoxicity, fatigue).
Direction: increased abemaciclib effect. Neither drug is a prodrug requiring activation here.
Evidence: theoretical; severity moderate; onset unspecified.
Management:
- If starting dose was 200 mg or 150 mg BID, reduce to 100 mg BID.
- If already reduced to 100 mg BID for adverse reactions, reduce further to 50 mg BID.
- On discontinuing voriconazole, resume the prior dose after 3 to 5 inhibitor half-lives.
- Monitor for CBC changes, GI toxicity, and hepatic effects.
What happens
Increased abemaciclib plasma concentration
Interaction Deep Dive
Taking abemaciclib together with a potent CYP3A4 inhibitor can raise plasma concentrations of both abemaciclib and its active metabolite, potentially increasing toxicity. When these agents are given together and abemaciclib was started at 200 mg or 150 mg twice daily, the abemaciclib dose should be lowered to 100 mg twice daily. For patients whose dose was already reduced to 100 mg twice daily because of adverse reactions, abemaciclib should be decreased further to 50 mg twice daily. Once the strong CYP3A inhibitor is stopped, the abemaciclib dose can be raised back to the level used prior to starting the strong inhibitor, doing so after 3-5 half-lives of the inhibitor have elapsed1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated abemaciclib metabolism
How to manage this interaction
The main point: keep taking both medicines as prescribed and let your care team coordinate the dosing. They can safely manage this combination.
- Your team may lower your abemaciclib dose while you are on voriconazole, then raise it back once the antifungal is stopped and has cleared your system.
- They may watch you more closely for side effects such as diarrhea, nausea, unusual tiredness, or signs of low blood counts.
- Tell your pharmacist or oncologist that you are (or will be) taking both, and report any new or worsening side effects promptly.
Do not start, stop, or change either drug on your own.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) In studies examining drug interactions, giving abemaciclib together with itraconazole (a potent CYP3A inhibitor) is expected to raise the AUC of abemaciclib along with its active metabolites (M2, M18 and M20) by 2.2-fold 1.
b) In drug interaction studies conducted in cancer patients, administering a single 50 mg dose of abemaciclib (0.3 times the approved 150 mg dose) alongside clarithromycin 500 mg twice daily (a potent CYP3A inhibitor) raised the AUC(0 to infinity) of abemaciclib together with its active metabolites (M2, M18, and M20) by 1.7-fold relative to abemaciclib given alone 1.
Common questions
Can I take Abemaciclib and Voriconazole together?
Voriconazole can raise abemaciclib levels and side effects, so your oncology team will likely lower the abemaciclib dose while you're on the antifungal and adjust it back afterward. Keep taking both as prescribed and report any new side effects. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abemaciclib and Voriconazole interaction?
It is rated moderate. Can be significant — usually manageable with 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 Voriconazole interaction managed?
The main point: keep taking both medicines as prescribed and let your care team coordinate the dosing. They can safely manage this combination. Your team may lower your abemaciclib dose while you are on voriconazole, then raise it back once the antifungal is stopped and has cleared your system. They may watch you more closely for side effects such as diarrhea, nausea, unusual tiredness, or signs o… 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 Voriconazole 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 anything you'd monitor while I'm on both?
References (1)
- Product Information: VERZENIO(TM) oral tablets, abemaciclib oral tablets. Lilly USA LLC (per FDA), Indianapolis, IN, 2017. DailyMed
Keep reading about Voriconazole
Keep reading about Abemaciclib
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