Drug interactions
Clozapine + Fentanyl transdermal
Severity: Major
Clozapine and Fentanyl transdermal: major interaction.
Last updated Sources: UK SmPC
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
Transdermal fentanyl gives sustained opioid exposure, and clozapine adds sedation, hypotension and risk of respiratory depression. The effects can persist for many hours after patch removal, complicating management of overdose.
What this interaction means in plain words
Clozapine and Fentanyl transdermal 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 CNS and respiratory depression with additive hypotension.
What to do
Titrate the patch cautiously and monitor sedation, respiratory rate and blood pressure, especially after dose changes. Avoid concurrent use of other sedatives where possible.
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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References
Other interactions of Clozapine
- Clozapine + Deferiprone Contraindicated
- Clozapine + Irinotecan Contraindicated
- Clozapine + Pimozide Contraindicated
- Clozapine + Thioridazine Contraindicated
- Acalabrutinib + Clozapine Major
- Adagrasib + Clozapine Major
Frequently asked questions
Can I take Clozapine with Fentanyl transdermal?
MediHelp rates the interaction as major. Clozapine and Fentanyl transdermal 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. Transdermal fentanyl gives sustained opioid exposure, and clozapine adds sedation, hypotension and risk of respiratory depression. The effects can persist for many hours after patch removal, complicating management of overdose.
How serious is the interaction between Clozapine and Fentanyl transdermal?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Titrate the patch cautiously and monitor sedation, respiratory rate and blood pressure, especially after dose changes. Avoid concurrent use of other sedatives where possible.
What other medicines interact with Clozapine?
MediHelp also lists interactions of Clozapine with, for example, Deferiprone, Irinotecan, Pimozide. The full list is on the Clozapine page.
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