Drug interactions
Phenytoin + Repaglinide
Severity: Moderate
Phenytoin 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
Phenytoin may reduce repaglinide exposure and weaken glycemic control, and phenytoin itself can raise glucose.
What this interaction means in plain words
Phenytoin 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.
Phenytoin belongs to Central Nervous System; Repaglinide belongs to Endocrine.
Why it happens
Phenytoin induces CYP3A4 and CYP2C8, increasing repaglinide metabolism.
What to do
Monitor blood glucose and titrate repaglinide upward as needed. Reassess the dose when phenytoin is stopped, since hypoglycemia can follow.
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 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 Repaglinide
- Gemfibrozil + Repaglinide Contraindicated
- Clarithromycin + Repaglinide Major
- Clopidogrel + Repaglinide Major
- Cobicistat + Repaglinide Major
- Cyclosporine + Repaglinide Major
- Cyclosporin + Repaglinide Major
Frequently asked questions
Can I take Phenytoin with Repaglinide?
MediHelp rates the interaction as moderate. Phenytoin 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. Phenytoin may reduce repaglinide exposure and weaken glycemic control, and phenytoin itself can raise glucose.
How serious is the interaction between Phenytoin 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 and titrate repaglinide upward as needed. Reassess the dose when phenytoin is stopped, since hypoglycemia can follow.
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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