Abemaciclib and Avacopan: 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
Avacopan
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.
Let's talk about taking avacopan (Tavneos) together with abemaciclib (Verzenio), your cancer medicine. Avacopan can slow down a liver enzyme (called CYP3A4) that normally helps clear abemaciclib out of your body. When that clearance slows, more abemaciclib can build up in your blood.
In real terms, that could mean stronger side effects from the abemaciclib, like diarrhea, tiredness, or low blood counts. The good news is this is very manageable. Please don't stop or change either medicine on your own. Your care team can watch you a little more closely and adjust your abemaciclib dose if needed to keep you safe.
Interaction: Avacopan is a moderate CYP3A4 inhibitor; abemaciclib is a CYP3A4 substrate with a narrow therapeutic index. Co-administration is expected to reduce abemaciclib metabolism, increasing its exposure (AUC/Cmax) and risk of dose-related toxicity.
- Direction: Increased abemaciclib effect/toxicity (neither drug is a prodrug).
- Mechanism: Inhibition of CYP3A4-mediated abemaciclib metabolism by avacopan.
- Evidence: Probable; onset unspecified.
- Management: Monitor closely for abemaciclib adverse effects (diarrhea, neutropenia, hepatotoxicity, fatigue); consider abemaciclib dose reduction per labeling, individualized by the care team.
What happens
Increased exposure to CYP3A4 substrate
Interaction Deep Dive
When avacopan, which inhibits CYP3A4, is taken together with a CYP3A4 substrate that has a narrow therapeutic index, the substrate's toxicity may be heightened; watch carefully for adverse reactions and think about lowering the dose of the CYP3A4 substrate1.
Why it happens (mechanism)
Inhibition of CYP3A4 substrate metabolism by avacopan
How to manage this interaction
This interaction is manageable when your team knows you take both drugs.
- Keep taking both as prescribed unless your prescriber tells you otherwise.
- Your care team may monitor you more closely for abemaciclib side effects such as diarrhea, unusual tiredness, signs of infection, or blood-count and liver changes.
- Your abemaciclib dose may need to be adjusted and individualized by your care team to keep it safe and effective.
- Tell your pharmacist or oncologist promptly if you notice new or worsening diarrhea, fever, or fatigue.
Ask your pharmacist to review your full medication list so any needed changes are made together.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) When simvastatin (a CYP3A4 substrate) was given together with avacopan at 60 mg daily for 7 days following food, the AUC and Cmax of simvastatin rose by 3.53-fold and 3.20-fold, respectively 1.
b) When midazolam (a CYP3A4 substrate) was given together with avacopan at 30 mg daily for 11 days on an empty stomach, the AUC and Cmax of simvastatin rose by 1.55-fold and 1.81-fold, respectively 1.
Common questions
Can I take Abemaciclib and Avacopan together?
Avacopan can raise abemaciclib levels and increase side effects, so your care team may monitor you more closely and adjust the abemaciclib dose. Keep taking both as prescribed and report new diarrhea, fever, or fatigue. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abemaciclib and Avacopan 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 Avacopan interaction managed?
This interaction is manageable when your team knows you take both drugs. Keep taking both as prescribed unless your prescriber tells you otherwise. Your care team may monitor you more closely for abemaciclib side effects such as diarrhea, unusual tiredness, signs of infection, or blood-count and liver changes. Your abemaciclib dose may need to be adjusted and individualized by your care team to ke… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Abemaciclib or Avacopan 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: TAVNEOS(R) oral capsules, avacopan oral capsules. ChemoCentryx Inc (per FDA), Thousand Oaks, CA, 2024. DailyMed
Keep reading about Avacopan
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.
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