Drug interactions
Phenytoin + Sorafenib
Severity: Major
Phenytoin and Sorafenib: 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 may lower sorafenib exposure and reduce its antitumor effect. The effect is predicted from other strong inducers, such as rifampin, that reduce sorafenib exposure.
What this interaction means in plain words
Phenytoin and Sorafenib 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; Sorafenib belongs to Oncology.
Why it happens
Phenytoin induces CYP3A4, which increases the clearance of sorafenib.
What to do
Avoid strong inducers where possible and select a non-inducing antiseizure drug. If the combination is unavoidable, monitor for reduced tumor response and consider the need for sorafenib dose adjustment.
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 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 Sorafenib
Frequently asked questions
Can I take Phenytoin with Sorafenib?
MediHelp rates the interaction as major. Phenytoin and Sorafenib 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 may lower sorafenib exposure and reduce its antitumor effect. The effect is predicted from other strong inducers, such as rifampin, that reduce sorafenib exposure.
How serious is the interaction between Phenytoin and Sorafenib?
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 strong inducers where possible and select a non-inducing antiseizure drug. If the combination is unavoidable, monitor for reduced tumor response and consider the need for sorafenib dose adjustment.
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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