Drug interactions
Etoposide + Fosphenytoin
Severity: Major
Etoposide and Fosphenytoin: 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, the active form of fosphenytoin, strongly induces CYP3A4 and can increase etoposide clearance. Reduced etoposide exposure may lower antitumor efficacy, and enzyme-inducing anticonvulsants have been linked to poorer outcomes.
What this interaction means in plain words
Etoposide and Fosphenytoin 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.
Etoposide belongs to Oncology; Fosphenytoin belongs to Central Nervous System.
Why it happens
Induction of CYP3A4 increases etoposide metabolism.
What to do
Where possible, switch to a non-enzyme-inducing antiseizure drug such as levetiracetam. If it must continue, monitor response and consider higher etoposide dosing guided by specialist oncology advice.
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 Etoposide
- Adenovirus types 4 and 7 live + Etoposide Contraindicated
- Etoposide + Pentostatin Contraindicated
- Cyclosporine + Etoposide Major
- Cyclosporin + Etoposide Major
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Etoposide Major
- Etoposide + Fingolimod Major
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Lurasidone Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
Frequently asked questions
Can I take Etoposide with Fosphenytoin?
MediHelp rates the interaction as major. Etoposide and Fosphenytoin 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, the active form of fosphenytoin, strongly induces CYP3A4 and can increase etoposide clearance. Reduced etoposide exposure may lower antitumor efficacy, and enzyme-inducing anticonvulsants have been linked to poorer outcomes.
How serious is the interaction between Etoposide and Fosphenytoin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Where possible, switch to a non-enzyme-inducing antiseizure drug such as levetiracetam. If it must continue, monitor response and consider higher etoposide dosing guided by specialist oncology advice.
What other medicines interact with Etoposide?
MediHelp also lists interactions of Etoposide with, for example, Adenovirus types 4 and 7 live, Pentostatin, Cyclosporine. The full list is on the Etoposide page.
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