Drug interactions
Fosphenytoin + Ixazomib
Severity: Major
Fosphenytoin and Ixazomib: 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
Fosphenytoin is converted to phenytoin, a strong CYP3A4 inducer. Strong inducers cut ixazomib exposure substantially, risking loss of efficacy.
What this interaction means in plain words
Fosphenytoin and Ixazomib 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.
Fosphenytoin belongs to Central Nervous System; Ixazomib belongs to Oncology.
Why it happens
Phenytoin induces CYP3A4, increasing ixazomib metabolism.
What to do
Avoid the combination and use a non-inducing anticonvulsant such as levetiracetam where possible.
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 Ixazomib
- Apalutamide + Ixazomib Major
- Carbamazepine + Ixazomib Major
- Dabrafenib + Ixazomib Major
- Enzalutamide + Ixazomib Major
- Etrasimod + Ixazomib Major
- Ixazomib + Lumacaftor / ivacaftor 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 Fosphenytoin with Ixazomib?
MediHelp rates the interaction as major. Fosphenytoin and Ixazomib 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. Fosphenytoin is converted to phenytoin, a strong CYP3A4 inducer. Strong inducers cut ixazomib exposure substantially, risking loss of efficacy.
How serious is the interaction between Fosphenytoin and Ixazomib?
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 the combination and use a non-inducing anticonvulsant such as levetiracetam where possible.
What other medicines interact with Ixazomib?
MediHelp also lists interactions of Ixazomib with, for example, Apalutamide, Carbamazepine, Dabrafenib. The full list is on the Ixazomib page.
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