Drug interactions
Heparin + Phenindione
Severity: Major
Heparin and Phenindione: 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
Both drugs impair coagulation by different routes, so together they increase the risk of bleeding. Overlap is intentional during initiation of an oral vitamin K antagonist, but heparin can also prolong the INR and complicate monitoring.
What this interaction means in plain words
Heparin and Phenindione 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 anticoagulation: heparin potentiates antithrombin while phenindione inhibits vitamin K-dependent clotting factor synthesis.
What to do
Use together only for planned bridging, monitoring INR and aPTT or anti-Xa, and stop heparin once the INR is therapeutic. Watch for bleeding.
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 Heparin
- Defibrotide + Heparin Contraindicated
- Heparin + Ketorolac Contraindicated
- Heparin + Oritavancin Contraindicated
- Acemetacin + Heparin Major
- Acetylsalicylic acid + Heparin Major
- Alteplase + Heparin Major
Frequently asked questions
Can I take Heparin with Phenindione?
MediHelp rates the interaction as major. Heparin and Phenindione 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. Both drugs impair coagulation by different routes, so together they increase the risk of bleeding. Overlap is intentional during initiation of an oral vitamin K antagonist, but heparin can also prolong the INR and complicate monitoring.
How serious is the interaction between Heparin and Phenindione?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use together only for planned bridging, monitoring INR and aPTT or anti-Xa, and stop heparin once the INR is therapeutic. Watch for bleeding.
What other medicines interact with Heparin?
MediHelp also lists interactions of Heparin with, for example, Defibrotide, Ketorolac, Oritavancin. The full list is on the Heparin page.
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