Ketoconazole Topical and Bosentan: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Bosentan
No brand names on recordKetoconazole 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 bosentan exposure
Interaction Deep Dive
Caution is warranted with the concurrent use of bosentan and ketoconazole1. Coadministration of ketoconazole, a potent CYP3A4 inhibitor, and bosentan may increase in bosentan exposure. While a dose adjustment is not necessary when these 2 agents are coadministered, patients may need to be monitored for increased bosentan adverse effects 21. Bosentan exposure increased by approximately 2-fold when 125 mg of bosentan twice daily was administered concomitantly with ketoconazole 1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of bosentan
Literature reports
2 reports — tap to read
a) Coadministration of bosentan 125 mg twice daily and ketoconazole, increased the plasma concentrations of bosentan by approximately 2-fold in normal volunteers 1.
b) Coadministration of bosentan 125 mg twice daily and ketoconazole, increased the exposure of bosentan by approximately 100% in normal volunteers 2.
Common questions
Can I take Ketoconazole Topical and Bosentan together?
Increased bosentan exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ketoconazole Topical and Bosentan interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
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 Bosentan 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: TRACLEER(R) oral tablets, oral suspension tablets, bosentan oral tablets, oral suspension tablets. Actelion Pharmaceuticals US Inc (per FDA), Titusville, NJ, 2024. DailyMed
Keep reading about Bosentan
Keep reading about Ketoconazole Topical
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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:
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