Ketoconazole Topical and Pimavanserin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ketoconazole Topical
Pimavanserin
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 pimavanserin exposure and an increased risk of QT interval prolongation
Interaction Deep Dive
Concomitant use of ketoconazole (a strong CYP3A4 inhibitor that may prolong the QT interval) with pimavanserin (a CYP3A4 substrate that prolongs QT) is contraindicated1. In a pharmacokinetic study, concurrent use of these agents significantly increased pimavanserin Cmax and AUC. The combination of ketoconazole and pimavanserin may also prolong QT interval 2 and result in life-threatening ventricular tachyarrhythmias such as torsade de pointes 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of pimavanserin; additive QT interval prolongation
Literature reports
1 report — tap to read
a) In a pharmacokinetic study, concurrent administration of ketoconazole with pimavanserin significantly increased pimavanserin Cmax by 1.5-fold and AUC by 3-fold 2.
Common questions
Can I take Ketoconazole Topical and Pimavanserin together?
Increased pimavanserin exposure and an increased risk of QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ketoconazole Topical and Pimavanserin interaction?
It is rated contraindicated. These should generally not be used together.
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 "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Ketoconazole Topical or Pimavanserin 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 (2)
- Product Information: Ketoconazole oral tablet, ketoconazole oral tablet. Taro Pharmaceuticals U.S.A. Inc. (per DailyMed), Hawthorne, NY, 2024. DailyMed
- Product Information: NUPLAZID(R) oral capsules, oral tablets, pimavanserin oral capsules, oral tablets. Acadia Pharmaceuticals Inc (per manufacturer), San Diego, CA, 2023. DailyMed
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