Abemaciclib and Berotralstat: 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
Berotralstat
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. Berotralstat (Orladeyo) gently slows down a liver enzyme called CYP3A4. Your body uses that same enzyme to break down abemaciclib (Verzenio). So when you take both, the abemaciclib may clear out of your body more slowly and build up a little higher than usual.
Because abemaciclib can cause side effects like diarrhea, low blood counts, tiredness, and other reactions, higher levels could make those more likely. The good news is this is very manageable. Your cancer care team can watch you closely and adjust your dose if needed. Keep taking both exactly as prescribed, and let your team know about any new or worsening side effects.
Mechanism: Berotralstat 150 mg is a moderate CYP3A4 inhibitor. Abemaciclib is a CYP3A4 substrate (not a prodrug), so inhibition reduces its metabolism and increases exposure (AUC/Cmax).
Effect: Elevated abemaciclib exposure with increased risk of substrate-related adverse reactions (diarrhea, neutropenia, hepatotoxicity, fatigue, venous thromboembolism).
- Direction: Increased abemaciclib effect/toxicity
- Severity: Major; evidence: theoretical; onset: unspecified
Management: Monitor for CDK4/6 inhibitor toxicity; abemaciclib dose may need to be individualized and reduced per prescribing guidance for moderate CYP3A4 inhibitors. Titrate as clinically indicated with closer monitoring of CBC and hepatic function.
What happens
Increased CYP3A4 substrate exposure and an increased CYP3A4 substrate-related adverse reactions
Interaction Deep Dive
Taking berotralstat 150 mg (which acts as a moderate CYP3A4 inhibitor) together with a CYP3A4 substrate that has a narrow therapeutic index can raise the exposure of the substrate and may heighten the likelihood of adverse reactions tied to those substrates. Carry out suitable monitoring and adjust the dose as needed1.
Why it happens (mechanism)
Inhibition of CYP3A4-substrate metabolism by berotralstat
How to manage this interaction
What your care team may do:
- Watch you more closely for abemaciclib side effects such as diarrhea, low blood counts, and liver changes.
- Adjust and individualize your abemaciclib dose if needed, since it may build up while you are on berotralstat.
- Order routine blood tests to keep an eye on things.
What you should do:
- Keep taking both medicines exactly as prescribed unless your team tells you otherwise.
- Report new or worsening diarrhea, unusual tiredness, fever, or signs of infection promptly.
- Ask your pharmacist or oncologist before starting or stopping either drug.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abemaciclib and Berotralstat together?
Berotralstat can raise abemaciclib levels and side effect risk by slowing its breakdown; keep taking both as prescribed and let your oncology team monitor you and adjust the abemaciclib dose if needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abemaciclib and Berotralstat 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 Berotralstat interaction managed?
What your care team may do: Watch you more closely for abemaciclib side effects such as diarrhea, low blood counts, and liver changes. Adjust and individualize your abemaciclib dose if needed, since it may build up while you are on berotralstat. Order routine blood tests to keep an eye on things. What you should do: Keep taking both medicines exactly as prescribed unless your team tells you otherw… 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 Berotralstat 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: ORLADEYO® oral capsules, oral pellets, berotralstat oral capsules, oral pellets. BioCryst Pharmaceuticals Inc (per manufacturer), Durham, NC, 2025. DailyMed
Keep reading about Berotralstat
Keep reading about Abemaciclib
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