Drug interactions
Nitisinone + Phenytoin
Severity: Moderate
Nitisinone 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
Nitisinone inhibits CYP2C9, the main enzyme clearing phenytoin, so phenytoin levels may rise. Phenytoin's narrow therapeutic range makes toxicity possible.
What this interaction means in plain words
Nitisinone 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.
Nitisinone belongs to Miscellaneous; Phenytoin belongs to Central Nervous System.
Why it happens
Nitisinone inhibits CYP2C9, reducing phenytoin metabolism.
What to do
Monitor phenytoin levels and signs of toxicity when nitisinone is started, and reduce the phenytoin dose if needed.
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 Nitisinone
- Adefovir + Nitisinone Moderate
- Bosentan + Nitisinone Moderate
- Celecoxib + Nitisinone Moderate
- Chlorpropamide + Nitisinone Moderate
- Diclofenac + Nitisinone Moderate
- Fluvastatin + Nitisinone Moderate
Frequently asked questions
Can I take Nitisinone with Phenytoin?
MediHelp rates the interaction as moderate. Nitisinone 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. Nitisinone inhibits CYP2C9, the main enzyme clearing phenytoin, so phenytoin levels may rise. Phenytoin's narrow therapeutic range makes toxicity possible.
How serious is the interaction between Nitisinone 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 nitisinone is started, and reduce the phenytoin dose if needed.
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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