Drug interactions
Fentanyl transdermal + Itraconazole
Severity: Major
Fentanyl transdermal and Itraconazole: 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
Itraconazole raises fentanyl concentrations by inhibiting CYP3A4 metabolism, and transdermal systems continue to release drug for many hours. This may cause profound sedation and fatal respiratory depression.
What this interaction means in plain words
Fentanyl transdermal and Itraconazole 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 decreases fentanyl clearance and increases systemic exposure.
What to do
Avoid the combination. If unavoidable, monitor for respiratory depression and sedation for several days after starting or stopping itraconazole and reduce the fentanyl dose.
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 Itraconazole
- Alfuzosin + Itraconazole Contraindicated
- Alprazolam + Itraconazole Contraindicated
- Avanafil + Itraconazole Contraindicated
- Conivaptan + Itraconazole Contraindicated
- Dihydroergotamine intranasal + Itraconazole Contraindicated
- Dihydroergotamine + Itraconazole Contraindicated
Frequently asked questions
Can I take Fentanyl transdermal with Itraconazole?
MediHelp rates the interaction as major. Fentanyl transdermal and Itraconazole 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. Itraconazole raises fentanyl concentrations by inhibiting CYP3A4 metabolism, and transdermal systems continue to release drug for many hours. This may cause profound sedation and fatal respiratory depression.
How serious is the interaction between Fentanyl transdermal and Itraconazole?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination. If unavoidable, monitor for respiratory depression and sedation for several days after starting or stopping itraconazole and reduce the fentanyl dose.
What other medicines interact with Itraconazole?
MediHelp also lists interactions of Itraconazole with, for example, Alfuzosin, Alprazolam, Avanafil. The full list is on the Itraconazole page.
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