Drug interactions
Fosphenytoin + Repaglinide
Severity: Moderate
Fosphenytoin and Repaglinide: moderate 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 CYP2C enzymes. Repaglinide levels may fall and blood glucose control may worsen.
What this interaction means in plain words
Fosphenytoin and Repaglinide can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Fosphenytoin belongs to Central Nervous System; Repaglinide belongs to Endocrine.
Why it happens
Phenytoin induces CYP3A4 and CYP2C8, accelerating repaglinide metabolism.
What to do
Monitor blood glucose when fosphenytoin is started, changed or stopped. Increase the repaglinide dose if control is lost.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Repaglinide
- Gemfibrozil + Repaglinide Contraindicated
- Clarithromycin + Repaglinide Major
- Clopidogrel + Repaglinide Major
- Cobicistat + Repaglinide Major
- Cyclosporin + Repaglinide Major
- Deferasirox + Repaglinide 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 Repaglinide?
MediHelp rates the interaction as moderate. Fosphenytoin and Repaglinide can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Fosphenytoin is converted to phenytoin, which induces CYP3A4 and CYP2C enzymes. Repaglinide levels may fall and blood glucose control may worsen.
How serious is the interaction between Fosphenytoin and Repaglinide?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood glucose when fosphenytoin is started, changed or stopped. Increase the repaglinide dose if control is lost.
What other medicines interact with Repaglinide?
MediHelp also lists interactions of Repaglinide with, for example, Gemfibrozil, Clarithromycin, Clopidogrel. The full list is on the Repaglinide page.
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