Drug interactions
Phenytoin + Rufinamide
Severity: Moderate
Phenytoin and Rufinamide: 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
Phenytoin can lower rufinamide concentrations, potentially reducing seizure control. Rufinamide may modestly raise phenytoin levels, so phenytoin toxicity is possible.
What this interaction means in plain words
Phenytoin and Rufinamide 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.
Phenytoin belongs to Central Nervous System; Rufinamide belongs to Central Nervous System.
Why it happens
Phenytoin induces enzymes that increase rufinamide clearance, and rufinamide may weakly inhibit CYP2C19, reducing phenytoin metabolism.
What to do
Monitor phenytoin concentrations and clinical response when starting or stopping rufinamide. Adjust the dose of either drug according to seizure control and signs of toxicity.
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
Other interactions of Rufinamide
- Carbamazepine + Rufinamide Moderate
- Desogestrel-ethinyl estradiol + Rufinamide Moderate
- Dronedarone + Rufinamide Moderate
- Esketamine + Rufinamide Moderate
- Ethinyl estradiol-drospirenone + Rufinamide Moderate
- Ethinyl estradiol-levonorgestrel + Rufinamide Moderate
Frequently asked questions
Can I take Phenytoin with Rufinamide?
MediHelp rates the interaction as moderate. Phenytoin and Rufinamide 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. Phenytoin can lower rufinamide concentrations, potentially reducing seizure control. Rufinamide may modestly raise phenytoin levels, so phenytoin toxicity is possible.
How serious is the interaction between Phenytoin and Rufinamide?
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 concentrations and clinical response when starting or stopping rufinamide. Adjust the dose of either drug according to seizure control and signs of toxicity.
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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