Abemaciclib and Lopinavir: 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
Lopinavir
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.
Here's what's going on. Your cancer medicine abemaciclib (Verzenio) is broken down by a liver enzyme called CYP3A4. Lopinavir slows that enzyme down. When the enzyme works slower, abemaciclib can build up in your body to higher levels than intended.
Higher levels can mean more side effects, like diarrhea, tiredness, or low blood counts. This is based on how the drugs are expected to behave rather than lots of real-world reports, but it's worth taking seriously. The good news is your care team can manage this easily, often by adjusting your abemaciclib dose and keeping a closer eye on you. Please don't change anything yourself, just talk with your oncologist or pharmacist.
Mechanism: Lopinavir inhibits CYP3A4, the primary enzyme metabolizing abemaciclib and its active metabolites. This reduces clearance and increases abemaciclib exposure (AUC/Cmax), raising the risk of dose-related toxicity (diarrhea, neutropenia, fatigue, hepatotoxicity). Neither agent is a prodrug in a way that reverses this, so the effect is a straightforward increase in abemaciclib activity.
- Direction: increased abemaciclib effect/toxicity
- Evidence: theoretical
- Onset: unspecified
- Management: If starting dose was 200 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 the inhibitor, resume the prior dose after 3 to 5 inhibitor half-lives. Monitor for toxicity.
What happens
Increased abemaciclib plasma concentration
Interaction Deep Dive
Taking abemaciclib together with a potent CYP3A4 inhibitor can raise plasma concentrations of abemaciclib and its active metabolite, potentially increasing toxicity. When these agents are given together and the initial abemaciclib dose was 200 mg or 150 mg twice daily, lower the abemaciclib dose to 100 mg twice daily. For patients whose dose was already reduced to 100 mg twice daily because of adverse reactions, cut the abemaciclib dose further to 50 mg twice daily. Once the strong CYP3A inhibitor is stopped, raise the abemaciclib dose (following 3-5 half-lives of the inhibitor) back to the dose that had been in place before the strong inhibitor was started1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated abemaciclib metabolism
How to manage this interaction
This is manageable with dose tailoring and monitoring. Keep taking both medicines exactly as prescribed unless your team tells you otherwise.
- Your oncologist may lower your abemaciclib dose while you are also taking lopinavir. Per the guidance, a 200 mg or 150 mg twice-daily dose is typically reduced to 100 mg twice daily, and if you were already at 100 mg twice daily for side effects, it may go to 50 mg twice daily.
- If the lopinavir is stopped, your team can raise the abemaciclib dose back to what you took before, after allowing time for the lopinavir to clear.
- Report any worsening diarrhea, unusual tiredness, fever, or signs of infection to your pharmacist or prescriber.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) In drug interaction studies, giving abemaciclib together with itraconazole (a strong CYP3A inhibitor) is expected to raise the AUC of abemaciclib together 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 strong 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 Lopinavir together?
Lopinavir can raise abemaciclib levels and side effects by slowing its breakdown, so your oncology team will likely lower the abemaciclib dose and monitor you more closely. Keep taking both as prescribed and let them make the adjustments. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abemaciclib and Lopinavir 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 Lopinavir interaction managed?
This is manageable with dose tailoring and monitoring. Keep taking both medicines exactly as prescribed unless your team tells you otherwise. Your oncologist may lower your abemaciclib dose while you are also taking lopinavir. Per the guidance, a 200 mg or 150 mg twice-daily dose is typically reduced to 100 mg twice daily, and if you were already at 100 mg twice daily for side effects, it may go t… 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 Lopinavir 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 Abemaciclib
Keep reading about Lopinavir
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist