Drug interactions
Fentanyl + Primidone
Severity: Major
Fentanyl and Primidone: 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
Primidone, converted partly to phenobarbital, induces CYP3A4 and can lower fentanyl concentrations, causing reduced pain control or opioid withdrawal in dependent patients. If primidone is stopped, fentanyl levels may rise and cause overdose and respiratory depression. Primidone also adds sedation.
What this interaction means in plain words
Fentanyl and Primidone 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.
Fentanyl belongs to Musculoskeletal; Primidone belongs to Central Nervous System.
Why it happens
CYP3A4 induction increasing fentanyl clearance, plus additive CNS depression.
What to do
Monitor analgesic response and withdrawal signs, and titrate fentanyl as needed. When primidone is started, stopped or changed, reassess fentanyl dosing and watch for sedation and respiratory depression.
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 Fentanyl
- Alvimopan + Fentanyl Contraindicated
- Fentanyl + Isocarboxazid Contraindicated
- Fentanyl + Olanzapine / samidorphan Contraindicated
- Fentanyl + Phenelzine Contraindicated
- Fentanyl + Tranylcypromine Contraindicated
- Alfentanil + Fentanyl Major
Other interactions of Primidone
- Lorlatinib + Primidone Contraindicated
- Lurasidone + Primidone Contraindicated
- Primidone + Ranolazine Contraindicated
- Primidone + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Primidone + Voriconazole Contraindicated
- Abiraterone + Primidone Major
Frequently asked questions
Can I take Fentanyl with Primidone?
MediHelp rates the interaction as major. Fentanyl and Primidone 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. Primidone, converted partly to phenobarbital, induces CYP3A4 and can lower fentanyl concentrations, causing reduced pain control or opioid withdrawal in dependent patients. If primidone is stopped, fentanyl levels may rise and cause overdose and respiratory depression. Primidone also adds sedation.
How serious is the interaction between Fentanyl and Primidone?
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 analgesic response and withdrawal signs, and titrate fentanyl as needed. When primidone is started, stopped or changed, reassess fentanyl dosing and watch for sedation and respiratory depression.
What other medicines interact with Fentanyl?
MediHelp also lists interactions of Fentanyl with, for example, Alvimopan, Isocarboxazid, Olanzapine / samidorphan. The full list is on the Fentanyl page.
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