Abemaciclib and Rifampin: 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
Rifampin
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.
Rifampin can weaken your cancer medicine, abemaciclib (Verzenio). Rifampin speeds up an enzyme in your liver called CYP3A4, and that enzyme breaks down abemaciclib. When abemaciclib gets cleared out faster, less of it stays in your body to fight the cancer. In studies, rifampin cut abemaciclib levels by about two-thirds, which is a big drop.
The concern here is that your cancer treatment could become less effective, not more dangerous in terms of side effects. Please don't change anything on your own. Talk with your oncologist or pharmacist, since they can often pick a different antibiotic or adjust your plan so your cancer treatment keeps working.
Effect: Rifampin (strong CYP3A4 inducer) increases CYP3A4-mediated metabolism of abemaciclib, reducing exposure of abemaciclib and its active metabolites and risking reduced efficacy.
- Direction/magnitude: Coadministration decreased abemaciclib AUC by ~67% in study data.
- Onset: Unspecified; enzyme induction typically develops over days to ~1-2 weeks.
- Evidence: Rated theoretical/major.
- Management: Avoid coadministration; select an alternative to the strong inducer where feasible. If a strong CYP3A4 inducer is unavoidable, dosing should be individualized by the care team and efficacy monitored closely.
What happens
Decreased abemaciclib plasma concentration
Interaction Deep Dive
Taking abemaciclib together with a potent CYP3A4 inducer can lower the plasma concentrations of both abemaciclib and its active metabolite, potentially reducing therapeutic effectiveness. Study data showed that giving rifampin, a strong CYP3A4 inducer, alongside abemaciclib reduced abemaciclib exposure by 67%. This combination should not be used, and alternative agents should be considered1.
Why it happens (mechanism)
Induction of CYP3A4-mediated abemaciclib metabolism
How to manage this interaction
The main goal is protecting how well your cancer medicine works. Because rifampin can markedly lower abemaciclib levels, the usual approach is to avoid using them together.
- Keep taking both as prescribed until you speak with your care team, do not stop on your own.
- Tell your oncology team and pharmacist that you have been prescribed rifampin, they may choose an alternative agent or adjust your plan.
- If both are truly needed, your team can individualize the dose and monitor your response more closely.
Ask your pharmacist before starting any new antibiotic or medication while on abemaciclib.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In drug interaction trials involving healthy participants, giving a single 200 mg dose of abemaciclib together with rifampin 600 mg daily (a potent CYP3A inducer) reduced the AUC(0 to infinity) of abemaciclib and its active metabolites (M2, M18, and M20) by 67% 1.
Common questions
Can I take Abemaciclib and Rifampin together?
Rifampin can cut abemaciclib levels by about two-thirds and weaken your cancer treatment, so this combination is usually avoided. Talk with your oncologist or pharmacist about an alternative before changing anything. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abemaciclib and Rifampin 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 Rifampin interaction managed?
The main goal is protecting how well your cancer medicine works. Because rifampin can markedly lower abemaciclib levels, the usual approach is to avoid using them together. Keep taking both as prescribed until you speak with your care team, do not stop on your own. Tell your oncology team and pharmacist that you have been prescribed rifampin, they may choose an alternative agent or adjust your pla… 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 Rifampin 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: VERZENIO(TM) oral tablets, abemaciclib oral tablets. Lilly USA LLC (per FDA), Indianapolis, IN, 2017. DailyMed
Keep reading about Rifampin
Keep reading about Abemaciclib
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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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