Drug interactions
Fludrocortisone + Fosphenytoin
Severity: Moderate
Fludrocortisone and Fosphenytoin: 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, induces corticosteroid metabolism and may lower fludrocortisone effect. In adrenal insufficiency this can lead to inadequate mineralocorticoid replacement, with hypotension or hyperkalemia.
What this interaction means in plain words
Fludrocortisone and Fosphenytoin 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.
Fludrocortisone belongs to Endocrine; Fosphenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4 and P-glycoprotein, increasing the clearance of fludrocortisone.
What to do
Monitor blood pressure, sodium and potassium, and increase the fludrocortisone dose as needed; reassess if fosphenytoin is stopped.
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 Fludrocortisone
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 Fludrocortisone with Fosphenytoin?
MediHelp rates the interaction as moderate. Fludrocortisone and Fosphenytoin 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, induces corticosteroid metabolism and may lower fludrocortisone effect. In adrenal insufficiency this can lead to inadequate mineralocorticoid replacement, with hypotension or hyperkalemia.
How serious is the interaction between Fludrocortisone and Fosphenytoin?
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 pressure, sodium and potassium, and increase the fludrocortisone dose as needed; reassess if fosphenytoin is stopped.
What other medicines interact with Fludrocortisone?
MediHelp also lists interactions of Fludrocortisone with, for example, Mifepristone, Aldesleukin, Amphotericin b. The full list is on the Fludrocortisone page.
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