Drug interactions
Phenytoin + Vonoprazan
Severity: Major
Phenytoin and Vonoprazan: 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 may lower vonoprazan exposure and reduce acid suppression, which could compromise healing or H. pylori eradication regimens.
What this interaction means in plain words
Phenytoin and Vonoprazan 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; Vonoprazan belongs to Gastrointestinal Tract.
Why it happens
Phenytoin induces CYP3A4, which contributes to vonoprazan metabolism.
What to do
Avoid concurrent use where possible and consider an alternative acid suppressant; monitor clinical response if combined.
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 Vonoprazan
- Amobarbital + Vonoprazan Major
- Apalutamide + Vonoprazan Major
- Atazanavir + Vonoprazan Major
- Carbamazepine + Vonoprazan Major
- Erlotinib + Vonoprazan Major
- Armodafinil + Vonoprazan Moderate
Frequently asked questions
Can I take Phenytoin with Vonoprazan?
MediHelp rates the interaction as major. Phenytoin and Vonoprazan 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 may lower vonoprazan exposure and reduce acid suppression, which could compromise healing or H. pylori eradication regimens.
How serious is the interaction between Phenytoin and Vonoprazan?
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 concurrent use where possible and consider an alternative acid suppressant; monitor clinical response if combined.
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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