Drug interactions
Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir
Severity: Contraindicated
Fosphenytoin and Sofosbuvir-velpatasvir-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
Fosphenytoin is metabolized to phenytoin, a potent inducer of CYP3A4 and P-gp. It can substantially lower concentrations of sofosbuvir, velpatasvir and voxilaprevir. This risks HCV treatment failure.
What this interaction means in plain words
Fosphenytoin and Sofosbuvir-velpatasvir-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.
Fosphenytoin belongs to Central Nervous System; Sofosbuvir-velpatasvir-voxilaprevir belongs to Anti Virals.
Why it happens
Phenytoin induces CYP3A4, CYP2B6 and P-gp, which increases clearance of the HCV drugs.
What to do
Do not coadminister; switch to a non-inducing anticonvulsant such as levetiracetam, or defer HCV therapy.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Fosphenytoin and Sofosbuvir-velpatasvir-voxilaprevir, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
Other interactions of Sofosbuvir-velpatasvir-voxilaprevir
- Phenobarbital + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Phenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Primidone + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Rifampin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Rifapentine + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Sofosbuvir-velpatasvir-voxilaprevir + St john's wort Contraindicated
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Lurasidone Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Abiraterone + Fosphenytoin Major
Frequently asked questions
Can I take Fosphenytoin with Sofosbuvir-velpatasvir-voxilaprevir?
MediHelp rates the interaction as contraindicated. Fosphenytoin and Sofosbuvir-velpatasvir-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. Fosphenytoin is metabolized to phenytoin, a potent inducer of CYP3A4 and P-gp. It can substantially lower concentrations of sofosbuvir, velpatasvir and voxilaprevir. This risks HCV treatment failure.
How serious is the interaction between Fosphenytoin and Sofosbuvir-velpatasvir-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: Do not coadminister; switch to a non-inducing anticonvulsant such as levetiracetam, or defer HCV therapy.
What other medicines interact with Sofosbuvir-velpatasvir-voxilaprevir?
MediHelp also lists interactions of Sofosbuvir-velpatasvir-voxilaprevir with, for example, Phenobarbital, Phenytoin, Primidone. The full list is on the Sofosbuvir-velpatasvir-voxilaprevir page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
