Drug interactions
Fosphenytoin + Glyburide-metformin
Severity: Moderate
Fosphenytoin and Glyburide-metformin: 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, the active form of fosphenytoin, can induce hepatic metabolism and may lower glyburide exposure. Phenytoin can also raise blood glucose by inhibiting insulin release, so overall glycemic control may deteriorate.
What this interaction means in plain words
Fosphenytoin and Glyburide-metformin 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; Glyburide-metformin belongs to Endocrine.
Why it happens
Phenytoin induces CYP2C9 and CYP3A4, increasing glyburide clearance, and inhibits pancreatic insulin secretion.
What to do
Monitor blood glucose when fosphenytoin is started, changed or stopped. Adjust the antidiabetic doses, and watch for hypoglycemia if the anticonvulsant is withdrawn.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 Glyburide-metformin
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 Glyburide-metformin?
MediHelp rates the interaction as moderate. Fosphenytoin and Glyburide-metformin 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, the active form of fosphenytoin, can induce hepatic metabolism and may lower glyburide exposure. Phenytoin can also raise blood glucose by inhibiting insulin release, so overall glycemic control may deteriorate.
How serious is the interaction between Fosphenytoin and Glyburide-metformin?
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. Adjust the antidiabetic doses, and watch for hypoglycemia if the anticonvulsant is withdrawn.
What other medicines interact with Glyburide-metformin?
MediHelp also lists interactions of Glyburide-metformin with, for example, Bosentan, Cholic acid, Clarithromycin. The full list is on the Glyburide-metformin page.
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