Drug interactions
Chitosan + Phenindione
Severity: Moderate
Chitosan and Phenindione: 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
Chitosan binds dietary fat and may reduce absorption of fat-soluble vitamins including vitamin K. In a patient taking a vitamin K antagonist such as phenindione, this could modestly increase the anticoagulant effect and raise INR.
What this interaction means in plain words
Chitosan and Phenindione 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
Chitosan binds lipids in the gut and may reduce absorption of fat-soluble vitamin K, adding to vitamin K antagonism.
What to do
Monitor INR when chitosan is started or stopped in patients on phenindione. Adjust the phenindione dose according to INR results.
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 Chitosan
- Chitosan + Heparin Minor
- Chitosan + Vitamin a Minor
- Chitosan + Vitamin e Minor
Frequently asked questions
Can I take Chitosan with Phenindione?
MediHelp rates the interaction as moderate. Chitosan and Phenindione 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. Chitosan binds dietary fat and may reduce absorption of fat-soluble vitamins including vitamin K. In a patient taking a vitamin K antagonist such as phenindione, this could modestly increase the anticoagulant effect and raise INR.
How serious is the interaction between Chitosan and Phenindione?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor INR when chitosan is started or stopped in patients on phenindione. Adjust the phenindione dose according to INR results.
What other medicines interact with Chitosan?
MediHelp also lists interactions of Chitosan with, for example, Heparin, Vitamin a, Vitamin e. The full list is on the Chitosan page.
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