Drug interactions
Fosphenytoin + Glipizide-metformin
Severity: Moderate
Fosphenytoin and Glipizide-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 inhibit insulin release and raise blood glucose, reducing antidiabetic efficacy. Phenytoin is also a CYP2C9 inducer and may lower glipizide levels.
What this interaction means in plain words
Fosphenytoin and Glipizide-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; Glipizide-metformin belongs to Endocrine.
Why it happens
Phenytoin inhibits insulin secretion and induces CYP2C9, increasing glipizide metabolism.
What to do
Monitor blood glucose when starting or stopping fosphenytoin and adjust glipizide and metformin doses accordingly.
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 Glipizide-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 Glipizide-metformin?
MediHelp rates the interaction as moderate. Fosphenytoin and Glipizide-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 inhibit insulin release and raise blood glucose, reducing antidiabetic efficacy. Phenytoin is also a CYP2C9 inducer and may lower glipizide levels.
How serious is the interaction between Fosphenytoin and Glipizide-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 starting or stopping fosphenytoin and adjust glipizide and metformin doses accordingly.
What other medicines interact with Glipizide-metformin?
MediHelp also lists interactions of Glipizide-metformin with, for example, Contrast media, Diatrizoate meglumine / diatrizoate, Diatrizoate. The full list is on the Glipizide-metformin page.
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