Drug interactions
Glimepiride-pioglitazone + Phenytoin
Severity: Moderate
Glimepiride-pioglitazone and Phenytoin: 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 induces CYP3A4 and CYP2C enzymes, which can lower exposure to both pioglitazone and glimepiride (a CYP2C9 substrate). Phenytoin can also inhibit insulin release and raise glucose, so glycemic control may worsen.
What this interaction means in plain words
Glimepiride-pioglitazone and Phenytoin 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.
Glimepiride-pioglitazone belongs to Endocrine; Phenytoin belongs to Central Nervous System.
Why it happens
Hepatic enzyme induction (CYP3A4, CYP2C8, CYP2C9) increasing drug clearance, plus phenytoin-related inhibition of insulin secretion.
What to do
Monitor blood glucose and HbA1c after starting or stopping phenytoin and increase antidiabetic doses if needed, reducing them again when phenytoin is withdrawn.
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 Glimepiride-pioglitazone
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
Frequently asked questions
Can I take Glimepiride-pioglitazone with Phenytoin?
MediHelp rates the interaction as moderate. Glimepiride-pioglitazone and Phenytoin 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 induces CYP3A4 and CYP2C enzymes, which can lower exposure to both pioglitazone and glimepiride (a CYP2C9 substrate). Phenytoin can also inhibit insulin release and raise glucose, so glycemic control may worsen.
How serious is the interaction between Glimepiride-pioglitazone and Phenytoin?
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 HbA1c after starting or stopping phenytoin and increase antidiabetic doses if needed, reducing them again when phenytoin is withdrawn.
What other medicines interact with Glimepiride-pioglitazone?
MediHelp also lists interactions of Glimepiride-pioglitazone with, for example, Fluconazole, Gemfibrozil, Insulin aspart. The full list is on the Glimepiride-pioglitazone page.
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