Drug interactions
Phenytoin + Temsirolimus
Severity: Major
Phenytoin and Temsirolimus: 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, a strong CYP3A4 inducer, can lower exposure to temsirolimus and its active metabolite sirolimus. Antitumor effect may be reduced.
What this interaction means in plain words
Phenytoin and Temsirolimus 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; Temsirolimus belongs to Oncology.
Why it happens
Phenytoin induces CYP3A4, increasing metabolism of temsirolimus and sirolimus.
What to do
Avoid strong CYP3A4 inducers where possible by using a non-inducing antiseizure drug. If unavoidable, labeling supports considering a higher temsirolimus dose with close monitoring.
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 Temsirolimus
- Bcg vaccine live + Temsirolimus Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Temsirolimus Contraindicated
- Measles mumps and rubella vaccine live + Temsirolimus Contraindicated
- Measles mumps rubella and varicella vaccine live + Temsirolimus Contraindicated
- Measles vaccine + Temsirolimus Contraindicated
- Rotavirus oral vaccine live + Temsirolimus Contraindicated
Frequently asked questions
Can I take Phenytoin with Temsirolimus?
MediHelp rates the interaction as major. Phenytoin and Temsirolimus 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, a strong CYP3A4 inducer, can lower exposure to temsirolimus and its active metabolite sirolimus. Antitumor effect may be reduced.
How serious is the interaction between Phenytoin and Temsirolimus?
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 strong CYP3A4 inducers where possible by using a non-inducing antiseizure drug. If unavoidable, labeling supports considering a higher temsirolimus dose with close monitoring.
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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