Drug interactions
Pentobarbital + Warfarin
Severity: Moderate
Pentobarbital and Warfarin: moderate 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, a barbiturate, induces hepatic drug-metabolizing enzymes and can accelerate warfarin clearance. This lowers the anticoagulant effect and may cause the INR to fall below the therapeutic range, with a risk of thrombosis. The effect can persist after the barbiturate is stopped, and warfarin requirements may then fall again.
What this interaction means in plain words
Pentobarbital and Warfarin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Barbiturate-mediated induction of hepatic CYP enzymes (including CYP2C9, CYP3A4 and CYP1A2) increases warfarin metabolism.
What to do
Check INR more often when pentobarbital is started or stopped and increase the warfarin dose as needed. Reduce the dose again, with close INR monitoring, once the barbiturate is withdrawn.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Warfarin
- Defibrotide + Warfarin Contraindicated
- Ketorolac + Warfarin Contraindicated
- Abciximab + Warfarin Major
- Acetylsalicylic acid + Warfarin Major
- Adagrasib + Warfarin Major
- Amiodarone + Warfarin Major
Frequently asked questions
Can I take Pentobarbital with Warfarin?
MediHelp rates the interaction as moderate. Pentobarbital and Warfarin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Pentobarbital, a barbiturate, induces hepatic drug-metabolizing enzymes and can accelerate warfarin clearance. This lowers the anticoagulant effect and may cause the INR to fall below the therapeutic range, with a risk of thrombosis. The effect can persist after the barbiturate is stopped, and warfarin requirements may then fall again.
How serious is the interaction between Pentobarbital and Warfarin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check INR more often when pentobarbital is started or stopped and increase the warfarin dose as needed. Reduce the dose again, with close INR monitoring, once the barbiturate is withdrawn.
What other medicines interact with Warfarin?
MediHelp also lists interactions of Warfarin with, for example, Defibrotide, Ketorolac, Abciximab. The full list is on the Warfarin page.
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