Drug interactions
Imatinib + Phenytoin
Severity: Major
Imatinib and Phenytoin: 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 lowers imatinib exposure and may reduce its antineoplastic efficacy. Imatinib may modestly raise phenytoin concentrations through CYP2C9 inhibition, adding a risk of phenytoin toxicity.
What this interaction means in plain words
Imatinib and Phenytoin 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.
Imatinib belongs to Oncology; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4 and P-glycoprotein, increasing imatinib clearance, while imatinib inhibits CYP2C9 and may reduce phenytoin metabolism.
What to do
Prefer a non-enzyme-inducing antiseizure drug. If the combination is unavoidable, raise the imatinib dose with careful response monitoring and check phenytoin levels.
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 Imatinib
- Imatinib + Lomitapide Contraindicated
- Imatinib + Lonafarnib Contraindicated
- Amobarbital + Imatinib Major
- Apalutamide + Imatinib Major
- Avapritinib + Imatinib Major
- Benzhydrocodone / acetaminophen + Imatinib Major
Frequently asked questions
Can I take Imatinib with Phenytoin?
MediHelp rates the interaction as major. Imatinib and Phenytoin 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 lowers imatinib exposure and may reduce its antineoplastic efficacy. Imatinib may modestly raise phenytoin concentrations through CYP2C9 inhibition, adding a risk of phenytoin toxicity.
How serious is the interaction between Imatinib and Phenytoin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Prefer a non-enzyme-inducing antiseizure drug. If the combination is unavoidable, raise the imatinib dose with careful response monitoring and check phenytoin levels.
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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