Drug interactions
Fentanyl + Pentobarbital
Severity: Major
Fentanyl and Pentobarbital: 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
Pentobarbital is a barbiturate that strongly depresses the CNS, and combined with fentanyl it can produce profound sedation, respiratory depression, coma and death. Barbiturates also induce CYP3A4 and may lower fentanyl exposure over time, making dosing unpredictable.
What this interaction means in plain words
Fentanyl and Pentobarbital 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, plus CYP3A4 induction by the barbiturate that accelerates fentanyl metabolism.
What to do
Avoid the combination where possible, or use reduced doses with continuous monitoring of respiration and sedation. Titrate fentanyl cautiously and reassess when the barbiturate is started or stopped.
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
Frequently asked questions
Can I take Fentanyl with Pentobarbital?
MediHelp rates the interaction as major. Fentanyl and Pentobarbital 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. Pentobarbital is a barbiturate that strongly depresses the CNS, and combined with fentanyl it can produce profound sedation, respiratory depression, coma and death. Barbiturates also induce CYP3A4 and may lower fentanyl exposure over time, making dosing unpredictable.
How serious is the interaction between Fentanyl and Pentobarbital?
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 where possible, or use reduced doses with continuous monitoring of respiration and sedation. Titrate fentanyl cautiously and reassess when the barbiturate is started or stopped.
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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