Drug interactions
Eslicarbazepine + Fosphenytoin
Severity: Moderate
Eslicarbazepine and Fosphenytoin: 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
Fosphenytoin (converted to phenytoin) can lower exposure to the active metabolite of eslicarbazepine, while eslicarbazepine can raise phenytoin concentrations. Phenytoin has a narrow therapeutic index, so toxicity such as ataxia, nystagmus and sedation may appear, and seizure control with eslicarbazepine may weaken.
What this interaction means in plain words
Eslicarbazepine and Fosphenytoin 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.
Eslicarbazepine belongs to Central Nervous System; Fosphenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces glucuronidation of the eslicarbazepine active metabolite, while eslicarbazepine inhibits CYP2C19, reducing phenytoin clearance.
What to do
Monitor phenytoin serum levels and clinical signs of toxicity, and reduce the fosphenytoin dose if levels rise. Assess seizure control and adjust the eslicarbazepine dose as 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 Eslicarbazepine
- Eslicarbazepine + Mavacamten Contraindicated
- Eslicarbazepine + Rilpivirine Contraindicated
- Artemether / lumefantrine + Eslicarbazepine Major
- Avapritinib + Eslicarbazepine Major
- Bedaquiline + Eslicarbazepine Major
- Benzhydrocodone / acetaminophen + Eslicarbazepine Major
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Lurasidone Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
Frequently asked questions
Can I take Eslicarbazepine with Fosphenytoin?
MediHelp rates the interaction as moderate. Eslicarbazepine and Fosphenytoin 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. Fosphenytoin (converted to phenytoin) can lower exposure to the active metabolite of eslicarbazepine, while eslicarbazepine can raise phenytoin concentrations. Phenytoin has a narrow therapeutic index, so toxicity such as ataxia, nystagmus and sedation may appear, and seizure control with eslicarbazepine may weaken.
How serious is the interaction between Eslicarbazepine and Fosphenytoin?
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 serum levels and clinical signs of toxicity, and reduce the fosphenytoin dose if levels rise. Assess seizure control and adjust the eslicarbazepine dose as needed.
What other medicines interact with Eslicarbazepine?
MediHelp also lists interactions of Eslicarbazepine with, for example, Mavacamten, Rilpivirine, Artemether / lumefantrine. The full list is on the Eslicarbazepine page.
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