Abemaciclib and Vonoprazan: 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
Vonoprazan
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. Vonoprazan (Voquezna) is a stomach acid medicine that also mildly slows down one of your body's main drug-processing pathways (an enzyme called CYP3A). Your cancer medicine abemaciclib (Verzenio) is broken down by that same pathway. So when you take them together, the abemaciclib may clear out of your body a little more slowly and build up higher than usual.
That could mean more of abemaciclib's usual side effects, like diarrhea, low blood counts, or fatigue. The good news is this is very manageable. Please don't change anything on your own. Your care team can watch you more closely and adjust your dose if needed. Just keep them in the loop about both medicines.
Mechanism: Vonoprazan is a weak CYP3A inhibitor. Abemaciclib is a CYP3A4 substrate, so inhibition may reduce its clearance and increase exposure (AUC/Cmax), potentially amplifying toxicity.
- Direction: Increased abemaciclib exposure and effect.
- Magnitude: Not quantified for this pair; vonoprazan raised midazolam AUC ~93% as a probe. Weak inhibition, so effect likely modest.
- Onset: Unspecified.
- Evidence: Theoretical.
Management: Monitor for abemaciclib adverse effects (diarrhea, neutropenia, elevated LFTs, fatigue, VTE). Dose reduction may be individualized by the oncology team if toxicity emerges. Avoid adding strong CYP3A inhibitors concurrently.
What happens
Increased CYP3A substrates exposure
Interaction Deep Dive
As a weak inhibitor of CYP3A, vonoprazan has the potential to raise the exposure of CYP3A substrates, which is a concern for agents where even small changes in concentration can trigger serious toxicities. In a study, a single oral 2 mg dose of midazolam (a CYP3A4 substrate) given after vonoprazan produced a 93% rise in midazolam AUC relative to midazolam given by itself. Combining vonoprazan with clarithromycin, which is a strong CYP3A inhibitor, adds to the potential for elevated exposure and adverse effects. Concentrations and/or adverse reactions associated with CYP3A substrates should be monitored frequently, and a reduction in dosage may be required123.
Why it happens (mechanism)
Inhibition of CYP3A-mediated metabolism by vonoprazan
How to manage this interaction
The main message: keep taking both as prescribed unless your care team tells you otherwise. This interaction is manageable with monitoring.
- Your team may watch you more closely for abemaciclib side effects such as diarrhea, low blood counts, fatigue, or signs of liver stress.
- Your abemaciclib dose may need to be adjusted and individualized by your oncology team if side effects show up.
- Tell your pharmacist and prescriber about every medicine you take, especially other drugs that can affect the CYP3A pathway (for example, certain antibiotics like clarithromycin).
- Report new or worsening diarrhea, unusual tiredness, fever, or easy bruising promptly.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
Common questions
Can I take Abemaciclib and Vonoprazan together?
Vonoprazan may modestly raise abemaciclib levels, so your oncology team may monitor you more closely and adjust the abemaciclib dose if needed; keep taking both as prescribed and report new side effects. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abemaciclib and Vonoprazan 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 Vonoprazan interaction managed?
The main message: keep taking both as prescribed unless your care team tells you otherwise. This interaction is manageable with monitoring. Your team may watch you more closely for abemaciclib side effects such as diarrhea, low blood counts, fatigue, or signs of liver stress. Your abemaciclib dose may need to be adjusted and individualized by your oncology team if side effects show up. Tell your p… 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 Vonoprazan 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 (3)
- Product Information: VOQUEZNA(R) oral tablets, vonoprazan oral tablets. Phathom Pharmaceuticals Inc (per FDA), Buffalo Grove, IL, 2023. DailyMed
- Product Information: VOQUEZNA(TM) DUAL PAK(TM) oral kit, vonoprazan oral tablets, amoxicillin oral capsules kit. Phathom Pharmaceuticals (per FDA), Buffalo Grove, IL, 2023. DailyMed
- Product Information: VOQUEZNA(TM) TRIPLE PAK(TM) oral kit, vonoprazan oral tablets, amoxicillin oral capsules, clarithromycin oral tablets kit. Phathom Pharmaceuticals (per FDA), Buffalo Grove, IL, 2023. DailyMed
Keep reading about Vonoprazan
Keep reading about Abemaciclib
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