Drug interactions
Fentanyl transmucosal + Ketoconazole
Severity: Major
Fentanyl transmucosal and Ketoconazole: major interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Ketoconazole increases systemic fentanyl exposure from the swallowed and absorbed portions of transmucosal products. This raises the risk of respiratory depression and heavy sedation.
What this interaction means in plain words
Fentanyl transmucosal and Ketoconazole can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Strong CYP3A4 inhibition reduces first-pass and systemic clearance of fentanyl.
What to do
Monitor frequently for respiratory depression and sedation and reduce the fentanyl dose or titrate cautiously while the inhibitor is in use.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
Frequently asked questions
Can I take Fentanyl transmucosal with Ketoconazole?
MediHelp rates the interaction as major. Fentanyl transmucosal and Ketoconazole can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Ketoconazole increases systemic fentanyl exposure from the swallowed and absorbed portions of transmucosal products. This raises the risk of respiratory depression and heavy sedation.
How serious is the interaction between Fentanyl transmucosal and Ketoconazole?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor frequently for respiratory depression and sedation and reduce the fentanyl dose or titrate cautiously while the inhibitor is in use.
What other medicines interact with Ketoconazole?
MediHelp also lists interactions of Ketoconazole with, for example, Alfuzosin, Alprazolam, Avanafil. The full list is on the Ketoconazole page.
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