Topotecan and Ketoconazole Topical: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ketoconazole Topical
Topotecan
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 topotecan exposure and risk of adverse events
Interaction Deep Dive
Concomitant use of oral topotecan (a P-gp substrate) and a P-gp inhibitor may increase systemic exposure of topotecan and increase the risk of adverse events. In a clinical study, coadministration of oral topotecan with cyclosporine A (a P-gp inhibitor) increased topotecan exposure 2- to 3-fold. Concomitant use of orally administered topotecan and P-gp inhibitors should be avoided1.
Why it happens (mechanism)
Inhibition of P-gp-mediated efflux transport of topotecan
Literature reports
1 report — tap to read
a) In a clinical study coadministration of single dose of cyclosporine A 15 mg/kg orally (P-gp inhibitor) within 4 hours of oral topotecan increased the dose-normalized AUC (0-24 hours) of topotecan lactone and total topotecan 2- to 3-fold compared with topotecan alone 1.
Common questions
Can I take Topotecan and Ketoconazole Topical together?
Increased topotecan exposure and risk of adverse events Always confirm with your pharmacist or prescriber before making any change.
How serious is the Topotecan and Ketoconazole Topical 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 Topotecan 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 a safer alternative to one of these medications for me?
References (1)
- Product Information: HYCAMTIN(R) oral capsules, topotecan oral capsules. Novartis Pharmaceuticals Corporation (per FDA), East Hanover, NJ, 2018. DailyMed
Keep reading about Ketoconazole Topical
Keep reading about Topotecan
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