Drug interactions
Floxuridine + Phenytoin
Severity: Moderate
Floxuridine and Phenytoin: 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
Fluoropyrimidines have been reported to raise phenytoin concentrations, leading to toxicity such as ataxia, nystagmus and confusion. Reports are limited but the effect can be clinically significant.
What this interaction means in plain words
Floxuridine and Phenytoin 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
Likely inhibition of CYP2C9-mediated phenytoin metabolism by fluoropyrimidines, though not firmly established.
What to do
Monitor phenytoin levels and signs of toxicity when starting or stopping floxuridine. Reduce the phenytoin dose if levels rise.
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 Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Frequently asked questions
Can I take Floxuridine with Phenytoin?
MediHelp rates the interaction as moderate. Floxuridine and Phenytoin 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. Fluoropyrimidines have been reported to raise phenytoin concentrations, leading to toxicity such as ataxia, nystagmus and confusion. Reports are limited but the effect can be clinically significant.
How serious is the interaction between Floxuridine and Phenytoin?
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 phenytoin levels and signs of toxicity when starting or stopping floxuridine. Reduce the phenytoin dose if levels rise.
What other medicines interact with Phenytoin?
MediHelp also lists interactions of Phenytoin with, for example, Artemether / lumefantrine, Bictegravir, Cabotegravir. The full list is on the Phenytoin page.
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