Drug interactions
Quinidine + Warfarin
Severity: Moderate
Quinidine 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
Quinidine can enhance the anticoagulant effect of warfarin and raise the INR. This increases the risk of bleeding, particularly when quinidine is started or its dose is changed.
What this interaction means in plain words
Quinidine 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.
Quinidine belongs to Anti Parasitic; Warfarin belongs to Cardiovascular.
Why it happens
Quinidine may reduce warfarin clearance and has been reported to impair vitamin K-dependent clotting factor synthesis, adding to warfarin's effect.
What to do
Check the INR more often when quinidine is started, stopped or adjusted, and reduce the warfarin dose as needed. Counsel the patient to report bleeding or bruising.
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 Quinidine
- Adagrasib + Quinidine Contraindicated
- Arsenic trioxide + Quinidine Contraindicated
- Artemether / lumefantrine + Quinidine Contraindicated
- Chloroquine + Quinidine Contraindicated
- Dofetilide + Quinidine Contraindicated
- Dronedarone + Quinidine Contraindicated
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 Quinidine with Warfarin?
MediHelp rates the interaction as moderate. Quinidine 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. Quinidine can enhance the anticoagulant effect of warfarin and raise the INR. This increases the risk of bleeding, particularly when quinidine is started or its dose is changed.
How serious is the interaction between Quinidine 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 the INR more often when quinidine is started, stopped or adjusted, and reduce the warfarin dose as needed. Counsel the patient to report bleeding or bruising.
What other medicines interact with Quinidine?
MediHelp also lists interactions of Quinidine with, for example, Adagrasib, Arsenic trioxide, Artemether / lumefantrine. The full list is on the Quinidine page.
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