Drug interactions
Phenytoin + Vinblastine
Severity: Moderate
Phenytoin and Vinblastine: 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
Chemotherapy regimens that include vinca alkaloids have been associated with low phenytoin levels and breakthrough seizures. Phenytoin may also lower vinca alkaloid exposure through enzyme induction.
What this interaction means in plain words
Phenytoin and Vinblastine 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.
Phenytoin belongs to Central Nervous System; Vinblastine belongs to Oncology.
Why it happens
Reduced phenytoin absorption from chemotherapy-related gut effects and altered metabolism. Phenytoin induces CYP3A4, which may increase vinblastine clearance.
What to do
Monitor phenytoin levels during chemotherapy and adjust the dose, or use an intravenous or non-inducing alternative.
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 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 Vinblastine
Frequently asked questions
Can I take Phenytoin with Vinblastine?
MediHelp rates the interaction as moderate. Phenytoin and Vinblastine 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. Chemotherapy regimens that include vinca alkaloids have been associated with low phenytoin levels and breakthrough seizures. Phenytoin may also lower vinca alkaloid exposure through enzyme induction.
How serious is the interaction between Phenytoin and Vinblastine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor phenytoin levels during chemotherapy and adjust the dose, or use an intravenous or non-inducing alternative.
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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