Drug interactions
Phenytoin + Voxilaprevir
Severity: Contraindicated
Phenytoin and Voxilaprevir: contraindicated 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 strongly induces metabolic enzymes and P-glycoprotein, which can substantially reduce voxilaprevir and sofosbuvir/velpatasvir exposure. This risks treatment failure and resistance in hepatitis C. Combination with such inducers is not recommended in labeling.
What this interaction means in plain words
Phenytoin and Voxilaprevir are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Phenytoin belongs to Central Nervous System; Voxilaprevir belongs to Anti Virals.
Why it happens
Phenytoin induces CYP3A4 and P-glycoprotein, increasing voxilaprevir clearance and reducing absorption.
What to do
Avoid concurrent use and change to a non-inducing anticonvulsant before starting HCV therapy if possible. Involve hepatology and neurology in the plan.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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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 Voxilaprevir
- Apalutamide + Voxilaprevir Contraindicated
- Bosentan + Voxilaprevir Major
- Carbamazepine + Voxilaprevir Major
- Efavirenz + Voxilaprevir Major
- Enzalutamide + Voxilaprevir Major
- Lorlatinib + Voxilaprevir Major
Frequently asked questions
Can I take Phenytoin with Voxilaprevir?
MediHelp rates the interaction as contraindicated. Phenytoin and Voxilaprevir are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Phenytoin strongly induces metabolic enzymes and P-glycoprotein, which can substantially reduce voxilaprevir and sofosbuvir/velpatasvir exposure. This risks treatment failure and resistance in hepatitis C. Combination with such inducers is not recommended in labeling.
How serious is the interaction between Phenytoin and Voxilaprevir?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid concurrent use and change to a non-inducing anticonvulsant before starting HCV therapy if possible. Involve hepatology and neurology in the plan.
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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