Ketoconazole Topical and Palbociclib: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Palbociclib
Ketoconazole Topical
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.
What happens
Increased palbociclib exposure
Interaction Deep Dive
Avoid concomitant use of palbociclib (a CYP3A substrate) with strong CYP3A inhibitors, as it may result in increased palbociclib exposure. When palbociclib was coadministered with itraconazole (a strong CYP3A inhibitor), the AUC and Cmax of palbociclib increased by 87% and 34%, respectively. Consider alternative comedications with no or minimal CYP3A inhibition; however, if coadministration is necessary, reduce the palbociclib dose to 75 mg once daily until the strong CYP3A inhibitor is discontinued. When 3 to 5 half-lives of the inhibitor have elapsed since discontinuation, increase the palbociclib dose to that used prior to initiating the strong CYP3A inhibitor1.
Why it happens (mechanism)
Inhibition of CYP3A-mediated palbociclib metabolism
Literature reports
1 report — tap to read
a) Concomitant use of palbociclib (a single 125 mg dose) and the strong CYP3A inhibitor, itraconazole (multiple doses of 200 mg/day), in 12 healthy subjects increased palbociclib AUC by 87% and Cmax by 34% compared with palbociclib alone 1.
Common questions
Can I take Ketoconazole Topical and Palbociclib together?
Increased palbociclib exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ketoconazole Topical and Palbociclib 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 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 Ketoconazole Topical or Palbociclib 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: IBRANCE(R) oral capsules, palbociclib oral capsules. Pfizer Labs (per FDA), New York, NY, 2016. DailyMed
Keep reading about Palbociclib
Keep reading about Ketoconazole Topical
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