Drug interactions
Fentanyl transdermal + Isoflurane
Severity: Major
Fentanyl transdermal and Isoflurane: 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
Patients on a fentanyl patch have ongoing opioid exposure that adds to the depressant effects of isoflurane. Together they can cause profound sedation, hypotension and respiratory depression. Fentanyl absorption continues after patch removal.
What this interaction means in plain words
Fentanyl transdermal and Isoflurane 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
Additive central nervous system and respiratory depression through opioid receptor agonism and enhancement of GABA-mediated inhibition by the volatile anesthetic.
What to do
Continue the patch as baseline analgesia as advised by the anesthesia team, and reduce other opioid and anesthetic doses accordingly. Monitor ventilation, oxygenation and blood pressure continuously, including during recovery.
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 Isoflurane
Frequently asked questions
Can I take Fentanyl transdermal with Isoflurane?
MediHelp rates the interaction as major. Fentanyl transdermal and Isoflurane 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. Patients on a fentanyl patch have ongoing opioid exposure that adds to the depressant effects of isoflurane. Together they can cause profound sedation, hypotension and respiratory depression. Fentanyl absorption continues after patch removal.
How serious is the interaction between Fentanyl transdermal and Isoflurane?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Continue the patch as baseline analgesia as advised by the anesthesia team, and reduce other opioid and anesthetic doses accordingly. Monitor ventilation, oxygenation and blood pressure continuously, including during recovery.
What other medicines interact with Isoflurane?
MediHelp also lists interactions of Isoflurane with, for example, Adrenaline-articaine, Amisulpride, Arsenic trioxide. The full list is on the Isoflurane page.
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