Drug interactions
Fosphenytoin + Rabeprazole
Severity: Minor
Fosphenytoin and Rabeprazole: minor 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, which induces CYP3A4 and CYP2C19 and may reduce proton pump inhibitor exposure. For rabeprazole the effect is likely small because of its non-enzymatic clearance, though reduced acid suppression is possible.
What this interaction means in plain words
Fosphenytoin and Rabeprazole have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Fosphenytoin belongs to Central Nervous System; Rabeprazole belongs to Gastrointestinal Tract.
Why it happens
Phenytoin-mediated enzyme induction may increase the oxidative metabolism of rabeprazole.
What to do
Monitor for reduced symptom control and increase the rabeprazole dose if needed. Also be aware that PPIs can alter phenytoin levels, so check phenytoin concentrations if clinically indicated.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Rabeprazole
- Rabeprazole + Rilpivirine Contraindicated
- Acalabrutinib + Rabeprazole Major
- Atazanavir + Rabeprazole Major
- Dacomitinib + Rabeprazole Major
- Dasatinib + Rabeprazole Major
- Erlotinib + Rabeprazole 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 Rabeprazole?
MediHelp rates the interaction as minor. Fosphenytoin and Rabeprazole have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Fosphenytoin is converted to phenytoin, which induces CYP3A4 and CYP2C19 and may reduce proton pump inhibitor exposure. For rabeprazole the effect is likely small because of its non-enzymatic clearance, though reduced acid suppression is possible.
How serious is the interaction between Fosphenytoin and Rabeprazole?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for reduced symptom control and increase the rabeprazole dose if needed. Also be aware that PPIs can alter phenytoin levels, so check phenytoin concentrations if clinically indicated.
What other medicines interact with Rabeprazole?
MediHelp also lists interactions of Rabeprazole with, for example, Rilpivirine, Acalabrutinib, Atazanavir. The full list is on the Rabeprazole page.
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