Drug interactions
Avatrombopag + Phenytoin
Severity: Moderate
Avatrombopag 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
Phenytoin induces CYP2C9 and CYP3A4, both of which metabolise avatrombopag. Platelet response to avatrombopag may be reduced.
What this interaction means in plain words
Avatrombopag 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.
Avatrombopag belongs to Miscellaneous; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP2C9 and CYP3A4, accelerating avatrombopag clearance.
What to do
In ITP, use the higher avatrombopag starting dose recommended in labeling for dual inducers. Monitor platelet counts and adjust the dose accordingly.
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 Avatrombopag
- Amiodarone + Avatrombopag Moderate
- Amobarbital + Avatrombopag Moderate
- Avatrombopag + Bosentan Moderate
- Avatrombopag + Carbamazepine Moderate
- Avatrombopag + Enzalutamide Moderate
- Avatrombopag + Fluconazole Moderate
Frequently asked questions
Can I take Avatrombopag with Phenytoin?
MediHelp rates the interaction as moderate. Avatrombopag 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. Phenytoin induces CYP2C9 and CYP3A4, both of which metabolise avatrombopag. Platelet response to avatrombopag may be reduced.
How serious is the interaction between Avatrombopag 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: In ITP, use the higher avatrombopag starting dose recommended in labeling for dual inducers. Monitor platelet counts and adjust the dose accordingly.
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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