Drug interactions
Phenytoin + Tiagabine
Severity: Moderate
Phenytoin and Tiagabine: 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 lowers tiagabine concentrations substantially, which may reduce seizure control. Tiagabine doses often need to be higher in patients taking enzyme inducers.
What this interaction means in plain words
Phenytoin and Tiagabine 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.
Why it happens
Phenytoin induces CYP3A4, increasing tiagabine clearance.
What to do
Titrate tiagabine to clinical response, and reassess the dose if phenytoin is started or stopped.
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
Frequently asked questions
Can I take Phenytoin with Tiagabine?
MediHelp rates the interaction as moderate. Phenytoin and Tiagabine 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 lowers tiagabine concentrations substantially, which may reduce seizure control. Tiagabine doses often need to be higher in patients taking enzyme inducers.
How serious is the interaction between Phenytoin and Tiagabine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Titrate tiagabine to clinical response, and reassess the dose if phenytoin is started or stopped.
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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