Drug interactions
Fosphenytoin + Saxagliptin
Severity: Moderate
Fosphenytoin and Saxagliptin: 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, an inducer of CYP3A4. Induction can lower saxagliptin exposure and may reduce glycemic efficacy, a pattern seen with other strong inducers such as rifampin, though the effect is smaller than with strong inducers.
What this interaction means in plain words
Fosphenytoin and Saxagliptin 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; Saxagliptin belongs to Endocrine.
Why it happens
CYP3A4 induction by phenytoin increases saxagliptin clearance.
What to do
Monitor glycemic control (fasting glucose, HbA1c) when fosphenytoin is started or stopped, and consider an alternative antidiabetic agent if control is inadequate.
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 Saxagliptin
- Albiglutide + Saxagliptin Moderate
- Amlodipine-benazepril + Saxagliptin Moderate
- Aripiprazole + Saxagliptin Moderate
- Asenapine + Saxagliptin Moderate
- Atazanavir + Saxagliptin Moderate
- Benazepril + Saxagliptin Moderate
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 Saxagliptin?
MediHelp rates the interaction as moderate. Fosphenytoin and Saxagliptin 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, an inducer of CYP3A4. Induction can lower saxagliptin exposure and may reduce glycemic efficacy, a pattern seen with other strong inducers such as rifampin, though the effect is smaller than with strong inducers.
How serious is the interaction between Fosphenytoin and Saxagliptin?
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 glycemic control (fasting glucose, HbA1c) when fosphenytoin is started or stopped, and consider an alternative antidiabetic agent if control is inadequate.
What other medicines interact with Saxagliptin?
MediHelp also lists interactions of Saxagliptin with, for example, Albiglutide, Amlodipine-benazepril, Aripiprazole. The full list is on the Saxagliptin page.
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