Drug interactions
Phenytoin + Sunitinib
Severity: Major
Phenytoin and Sunitinib: 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 CYP3A4 inducer and can substantially lower sunitinib and its active metabolite exposure. This may reduce antitumor efficacy.
What this interaction means in plain words
Phenytoin and Sunitinib 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; Sunitinib belongs to Oncology.
Why it happens
Phenytoin induces CYP3A4, increasing sunitinib clearance.
What to do
Choose a non-enzyme-inducing antiseizure drug where possible. If the combination is unavoidable, the sunitinib dose may need to be increased with careful monitoring of tolerability and response.
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 Sunitinib
- Adagrasib + Sunitinib Major
- Amiodarone + Sunitinib Major
- Amisulpride + Sunitinib Major
- Anagrelide + Sunitinib Major
- Apalutamide + Sunitinib Major
- Arsenic trioxide + Sunitinib Major
Frequently asked questions
Can I take Phenytoin with Sunitinib?
MediHelp rates the interaction as major. Phenytoin and Sunitinib 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 CYP3A4 inducer and can substantially lower sunitinib and its active metabolite exposure. This may reduce antitumor efficacy.
How serious is the interaction between Phenytoin and Sunitinib?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Choose a non-enzyme-inducing antiseizure drug where possible. If the combination is unavoidable, the sunitinib dose may need to be increased with careful monitoring of tolerability and response.
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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