Drug interactions
Fosphenytoin + Glimepiride-pioglitazone
Severity: Moderate
Fosphenytoin and Glimepiride-pioglitazone: 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, a broad enzyme inducer that may increase the metabolism of pioglitazone and glimepiride, lowering their exposure. Phenytoin can also impair insulin secretion and raise blood glucose. Glycemic control may therefore worsen.
What this interaction means in plain words
Fosphenytoin and Glimepiride-pioglitazone 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; Glimepiride-pioglitazone belongs to Endocrine.
Why it happens
Phenytoin induces CYP3A4, CYP2C8 and CYP2C9, increasing clearance of the antidiabetic drugs, and may inhibit insulin release.
What to do
Monitor blood glucose and HbA1c after starting or stopping fosphenytoin. Increase antidiabetic doses if control worsens, and reduce them if phenytoin is withdrawn.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 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 Glimepiride-pioglitazone?
MediHelp rates the interaction as moderate. Fosphenytoin and Glimepiride-pioglitazone 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, a broad enzyme inducer that may increase the metabolism of pioglitazone and glimepiride, lowering their exposure. Phenytoin can also impair insulin secretion and raise blood glucose. Glycemic control may therefore worsen.
How serious is the interaction between Fosphenytoin and Glimepiride-pioglitazone?
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 fosphenytoin. Increase antidiabetic doses if control worsens, and reduce them if 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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