Drug interactions
Phenytoin + Venetoclax
Severity: Major
Phenytoin and Venetoclax: 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 can reduce venetoclax exposure, risking reduced antileukemic efficacy. Labeling advises avoiding strong or moderate CYP3A inducers.
What this interaction means in plain words
Phenytoin and Venetoclax 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; Venetoclax belongs to Miscellaneous.
Why it happens
Phenytoin induces CYP3A4, accelerating venetoclax metabolism.
What to do
Avoid the combination and use an alternative anticonvulsant with little CYP3A induction such as levetiracetam.
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 Venetoclax
- Clarithromycin + Venetoclax Contraindicated
- Itraconazole + Venetoclax Contraindicated
- Ketoconazole + Venetoclax Contraindicated
- Posaconazole + Venetoclax Contraindicated
- Venetoclax + Voriconazole Contraindicated
- Amiodarone + Venetoclax Major
Frequently asked questions
Can I take Phenytoin with Venetoclax?
MediHelp rates the interaction as major. Phenytoin and Venetoclax 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 can reduce venetoclax exposure, risking reduced antileukemic efficacy. Labeling advises avoiding strong or moderate CYP3A inducers.
How serious is the interaction between Phenytoin and Venetoclax?
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 the combination and use an alternative anticonvulsant with little CYP3A induction such as levetiracetam.
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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