Drug interactions
Ifosfamide + Phenytoin
Severity: Moderate
Ifosfamide and Phenytoin: 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
Phenytoin induces hepatic enzymes that convert ifosfamide to its active alkylating metabolites and also to the chloroacetaldehyde metabolite linked to neurotoxicity and nephrotoxicity. Exposure to these metabolites may rise, increasing both activity and toxicity. Ifosfamide may also change phenytoin exposure, which could affect seizure control.
What this interaction means in plain words
Ifosfamide and Phenytoin 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.
Ifosfamide belongs to Oncology; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4 and CYP2B6, increasing bioactivation and the formation of toxic ifosfamide metabolites.
What to do
Monitor for neurotoxicity, renal function and myelosuppression during ifosfamide therapy, and consider a non-inducing antiseizure drug. Check phenytoin levels if seizure control changes.
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 Ifosfamide
- Adenovirus types 4 and 7 live + Ifosfamide Contraindicated
- Ifosfamide + Measles mumps and rubella vaccine Contraindicated
- Ifosfamide + Measles mumps and rubella vaccine live Contraindicated
- Ifosfamide + Measles mumps rubella and varicella vaccine live Contraindicated
- Ifosfamide + Measles vaccine Contraindicated
- Ifosfamide + Rotavirus oral vaccine live Contraindicated
Frequently asked questions
Can I take Ifosfamide with Phenytoin?
MediHelp rates the interaction as moderate. Ifosfamide and Phenytoin 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 induces hepatic enzymes that convert ifosfamide to its active alkylating metabolites and also to the chloroacetaldehyde metabolite linked to neurotoxicity and nephrotoxicity. Exposure to these metabolites may rise, increasing both activity and toxicity. Ifosfamide may also change phenytoin exposure, which could affect seizure control.
How serious is the interaction between Ifosfamide and Phenytoin?
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 for neurotoxicity, renal function and myelosuppression during ifosfamide therapy, and consider a non-inducing antiseizure drug. Check phenytoin levels if seizure control changes.
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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