Drug interactions
Phenytoin + Sofosbuvir
Severity: Major
Phenytoin and Sofosbuvir: major 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 is a strong inducer and is expected to markedly lower sofosbuvir levels. This could cause loss of antiviral efficacy and hepatitis C treatment failure.
What this interaction means in plain words
Phenytoin and Sofosbuvir can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Phenytoin belongs to Central Nervous System; Sofosbuvir belongs to Anti Virals.
Why it happens
Induction of intestinal P-glycoprotein by phenytoin reduces sofosbuvir absorption and active metabolite exposure.
What to do
Avoid coadministration as labeling advises. Use an alternative anticonvulsant without inducing effects during hepatitis C therapy.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Sofosbuvir
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 Sofosbuvir?
MediHelp rates the interaction as major. Phenytoin and Sofosbuvir can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Phenytoin is a strong inducer and is expected to markedly lower sofosbuvir levels. This could cause loss of antiviral efficacy and hepatitis C treatment failure.
How serious is the interaction between Phenytoin and Sofosbuvir?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid coadministration as labeling advises. Use an alternative anticonvulsant without inducing effects during hepatitis C therapy.
What other medicines interact with Sofosbuvir?
MediHelp also lists interactions of Sofosbuvir with, for example, Amiodarone, Apalutamide, Carbamazepine. The full list is on the Sofosbuvir page.
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