Alosetron and Ketoconazole Topical: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Alosetron
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 alosetron exposure
Interaction Deep Dive
Ketoconazole is a potent inhibitor of the CYP3A4-mediated metabolism of alosetron. Concomitant use of alosetron and ketoconazole increased the AUC of alosetron by 29% in one study. This may increase the risk of constipation and other serious bowel side effects, including ischemic colitis. Caution should be exercised with the coadministration of alosetron and ketoconazole1.
Why it happens (mechanism)
Inhibition by ketoconazole of CYP3A4-mediated alosetron metabolism
Literature reports
1 report — tap to read
a) Ketoconazole inhibits the CYP3A4-mediated metabolism of alosetron. In a pharmacokinetic study involving 38 healthy female subjects, participants received ketoconazole 200 mg twice daily for 7 days. On day 7, participants also received a single 1-mg dose of alosetron. The mean area under the concentration-time curve (AUC) of alosetron increased by 29% 1.
Common questions
Can I take Alosetron and Ketoconazole Topical together?
Increased alosetron exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Alosetron and Ketoconazole Topical 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 strong is the evidence for this interaction?
The evidence is graded "established". Well documented — supported by controlled studies or strong clinical data.
Questions for your pharmacist
- Does my dose of Alosetron or Ketoconazole Topical 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: LOTRONEX(R) oral tablets, alosetron hcl oral tablets. Prometheus Laboratories,Inc, San Diego, CA, 2008. DailyMed
Keep reading about Alosetron
Keep reading about Ketoconazole Topical
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