Drug interactions
Phenytoin + Teniposide
Severity: Major
Phenytoin and Teniposide: 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 markedly increases teniposide clearance, lowering exposure and potentially reducing antitumor efficacy. Patients on enzyme-inducing anticonvulsants have shown higher teniposide clearance.
What this interaction means in plain words
Phenytoin and Teniposide 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.
Why it happens
Phenytoin induces CYP3A4, increasing teniposide metabolism.
What to do
Prefer a non-enzyme-inducing antiseizure drug during teniposide therapy. If unavoidable, monitor response and consider teniposide dose adjustment by the oncology team.
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
Frequently asked questions
Can I take Phenytoin with Teniposide?
MediHelp rates the interaction as major. Phenytoin and Teniposide 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 markedly increases teniposide clearance, lowering exposure and potentially reducing antitumor efficacy. Patients on enzyme-inducing anticonvulsants have shown higher teniposide clearance.
How serious is the interaction between Phenytoin and Teniposide?
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 during teniposide therapy. If unavoidable, monitor response and consider teniposide dose adjustment by the oncology team.
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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