Drug interactions
Fosphenytoin + Sorafenib
Severity: Moderate
Fosphenytoin and Sorafenib: 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
Fosphenytoin is converted to phenytoin, a CYP3A4 inducer that can lower sorafenib exposure and reduce antitumor efficacy. Sorafenib may also affect phenytoin concentrations.
What this interaction means in plain words
Fosphenytoin and Sorafenib 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; Sorafenib belongs to Oncology.
Why it happens
Phenytoin induction of CYP3A4 and other enzymes increases sorafenib clearance.
What to do
Use a non-inducing anticonvulsant when possible. If the combination is needed, monitor tumor response and phenytoin levels.
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 Sorafenib
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 Sorafenib?
MediHelp rates the interaction as moderate. Fosphenytoin and Sorafenib 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 is converted to phenytoin, a CYP3A4 inducer that can lower sorafenib exposure and reduce antitumor efficacy. Sorafenib may also affect phenytoin concentrations.
How serious is the interaction between Fosphenytoin and Sorafenib?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use a non-inducing anticonvulsant when possible. If the combination is needed, monitor tumor response and phenytoin levels.
What other medicines interact with Sorafenib?
MediHelp also lists interactions of Sorafenib with, for example, Adagrasib, Amiodarone, Amisulpride. The full list is on the Sorafenib page.
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