Abemaciclib and Xanomeline: 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
Abemaciclib
Xanomeline
No brand names on record
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.
You've been prescribed abemaciclib (Verzenio), a cancer pill, along with xanomeline. Here's the simple version: your body uses a liver-and-gut enzyme called CYP3A4 to break down abemaciclib. Xanomeline can briefly slow that enzyme down in your gut. When that happens, a bit more abemaciclib may stay in your system, which could make its side effects (like diarrhea, tiredness, nausea, or low blood counts) show up more often or feel stronger.
The good news is this is a theoretical concern, and it's very manageable. Your care team can watch you a little more closely and adjust your dose if needed. Please don't change anything on your own, just keep your team in the loop about how you feel.
Effect: Xanomeline transiently inhibits intestinal (not systemic) CYP3A4. Abemaciclib is a sensitive oral CYP3A4 substrate, so co-administration may increase abemaciclib exposure (AUC/Cmax) and raise the frequency/severity of dose-related adverse effects.
- Direction: increased abemaciclib effect/toxicity (inhibitor + non-prodrug substrate).
- Adverse effects to watch: diarrhea, neutropenia, hepatotoxicity (transaminases), fatigue, nausea, VTE.
- Onset: unspecified; evidence: theoretical.
- Magnitude: likely modest given gut-localized, transient inhibition.
Management: Monitor for enhanced abemaciclib toxicity; CBC and LFTs per abemaciclib protocol. Dose may be individualized by the oncology team if toxicity emerges.
What happens
Increased oral sensitive CYP3A4 substrate exposure and an increased risk on severity and frequency of sensitive CYP3A4 substrate-related adverse reactions
Interaction Deep Dive
In the gut, xanomeline causes transient local inhibition of CYP3A4, though this effect does not extend systemically. When xanomeline is taken together with oral medications that are sensitive CYP3A4 substrates, the exposure to those oral sensitive CYP3A4 substrates may rise. Such an increase in exposure can lead to a greater frequency and/or severity of adverse reactions associated with these substrates. In cases of concomitant use, watch patients for any rise in the frequency and/or severity of adverse reactions tied to oral drugs that are sensitive substrates of CYP3A41.
Why it happens (mechanism)
Inhibition of CYP3A4-substrate metabolism by xanomeline
How to manage this interaction
This interaction is manageable. Here's the practical approach:
- Keep taking both exactly as prescribed unless your care team tells you otherwise.
- Your team may monitor you more closely for abemaciclib side effects (such as diarrhea, unusual tiredness, fever or signs of infection, and blood-count or liver-function checks).
- The abemaciclib dose may need to be adjusted and individualized by your oncology team if side effects increase.
What to raise with your pharmacist or prescriber: any new or worsening diarrhea, fatigue, nausea, fever, or bruising, and make sure both drugs are listed on your medication record.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Abemaciclib and Xanomeline together?
Xanomeline may modestly increase abemaciclib levels and side effects by slowing its breakdown in the gut; keep taking both as prescribed and report any worsening side effects so your team can adjust the dose or monitor you more closely. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abemaciclib and Xanomeline 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 Xanomeline interaction managed?
This interaction is manageable. Here's the practical approach: Keep taking both exactly as prescribed unless your care team tells you otherwise. Your team may monitor you more closely for abemaciclib side effects (such as diarrhea, unusual tiredness, fever or signs of infection, and blood-count or liver-function checks). The abemaciclib dose may need to be adjusted and individualized by your oncol… 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 Xanomeline 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: COBENFY(TM) oral capsules, xanomeline, trospium chloride oral capsules. Bristol-Myers Squibb Company (Per FDA), Princeton, NJ, 2024. DailyMed
Keep reading about Abemaciclib
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