Drug interactions
Fosphenytoin + Vigabatrin
Severity: Moderate
Fosphenytoin and Vigabatrin: 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
Adding vigabatrin can lower plasma phenytoin concentrations, the active form of fosphenytoin. This may reduce seizure control in some patients.
What this interaction means in plain words
Fosphenytoin and Vigabatrin 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 belongs to Central Nervous System; Vigabatrin belongs to Central Nervous System.
Why it happens
The mechanism is not established; vigabatrin may alter phenytoin metabolism or disposition.
What to do
Monitor phenytoin levels when vigabatrin is started, changed or stopped. Adjust the fosphenytoin/phenytoin dose according to levels and seizure control.
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 Vigabatrin
- Amisulpride + Vigabatrin Moderate
- Asenapine transdermal + Vigabatrin Moderate
- Asenapine + Vigabatrin Moderate
- Avapritinib + Vigabatrin Moderate
- Benzhydrocodone / acetaminophen + Vigabatrin Moderate
- Brexanolone + Vigabatrin Moderate
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 Fosphenytoin with Vigabatrin?
MediHelp rates the interaction as moderate. Fosphenytoin and Vigabatrin 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. Adding vigabatrin can lower plasma phenytoin concentrations, the active form of fosphenytoin. This may reduce seizure control in some patients.
How serious is the interaction between Fosphenytoin and Vigabatrin?
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 when vigabatrin is started, changed or stopped. Adjust the fosphenytoin/phenytoin dose according to levels and seizure control.
What other medicines interact with Vigabatrin?
MediHelp also lists interactions of Vigabatrin with, for example, Amisulpride, Asenapine transdermal, Asenapine. The full list is on the Vigabatrin page.
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