Drug interactions
Phenindione + Vitamin e
Severity: Moderate
Phenindione and Vitamin e: 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
Phenindione is an oral vitamin K antagonist, and high doses of vitamin E may further impair vitamin K-dependent clotting and platelet function. This may increase bleeding risk, mainly with megadoses.
What this interaction means in plain words
Phenindione and Vitamin e 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
High-dose vitamin E antagonizes vitamin K-dependent clotting factor synthesis and inhibits platelet aggregation, adding to phenindione's effect.
What to do
Avoid vitamin E megadoses in patients on phenindione. Monitor INR and bleeding signs if supplementation is started or stopped.
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 Vitamin e
- Betrixaban + Vitamin e Moderate
- Selumetinib + Vitamin e Moderate
- Vitamin e + Warfarin Moderate
- Alfalfa + Vitamin e Minor
- Antithrombin alfa + Vitamin e Minor
- Antithrombin iii + Vitamin e Minor
Frequently asked questions
Can I take Phenindione with Vitamin e?
MediHelp rates the interaction as moderate. Phenindione and Vitamin e 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. Phenindione is an oral vitamin K antagonist, and high doses of vitamin E may further impair vitamin K-dependent clotting and platelet function. This may increase bleeding risk, mainly with megadoses.
How serious is the interaction between Phenindione and Vitamin e?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid vitamin E megadoses in patients on phenindione. Monitor INR and bleeding signs if supplementation is started or stopped.
What other medicines interact with Vitamin e?
MediHelp also lists interactions of Vitamin e with, for example, Betrixaban, Selumetinib, Warfarin. The full list is on the Vitamin e page.
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