fludrocortisone acetate
Brand: Florinef
Prototype Drug
Drug Class: mineralocorticoid
Drug Family: corticosteroid
Subclass: synthetic mineralocorticoid
Organ Systems: endocrine
Mechanism of Action
Potent synthetic mineralocorticoid that binds the mineralocorticoid receptor in renal collecting duct principal cells, stimulating expression of sodium channels (ENaC) and Na+/K+-ATPase pumps, causing sodium and water retention with potassium and hydrogen ion secretion.
mineralocorticoid receptor (MR) in renal collecting duct
Indications
- primary adrenal insufficiency (Addison's disease) — mineralocorticoid replacement
- salt-losing congenital adrenal hyperplasia
- orthostatic hypotension (off-label)
Contraindications
- systemic fungal infections
- hypertension
- heart failure
- edema states
Adverse Effects
Common
- edema
- hypertension
- weight gain
- headache
Serious
- hypokalemia
- hypertension (severe)
- congestive heart failure
- Cushing's syndrome (at high doses)
Pharmacokinetics (ADME)
| Absorption | oral; rapid and complete absorption |
| Distribution | ~42% protein bound |
| Metabolism | hepatic |
| Excretion | renal |
| Half-life | 3.5 hours (plasma); 18–36 hours (biologic effect) |
| Onset | hours |
| Peak | 1.7 hours |
| Duration | 24–36 hours (biologic) |
| Protein Binding | 42% |
| Vd | moderate |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| diuretics | additive electrolyte effects; thiazides may potentiate hypokalemia | moderate |
| NSAIDs | blunt mineralocorticoid-mediated sodium retention, reducing fludrocortisone efficacy | moderate |
| potassium-depleting agents | additive hypokalemia | moderate |
Nursing Considerations
- Monitor blood pressure, electrolytes (sodium, potassium), and weight at each visit during dose titration.
- Typical dose for adrenal insufficiency is 0.05–0.1 mg daily; titrate to normalize electrolytes and blood pressure.
- Educate patients on sick day dosing for hydrocortisone (not fludrocortisone; the glucocorticoid dose is increased during illness).
- Warn patients to avoid excessive sodium restriction, which could counteract mineralocorticoid replacement.
Clinical Pearls
- Fludrocortisone is the only oral mineralocorticoid available; dexamethasone and prednisone have negligible mineralocorticoid activity and cannot substitute for fludrocortisone in adrenal insufficiency.
- Adequate mineralocorticoid replacement (avoiding hyponatremia and hyperkalemia) is essential for hemodynamic stability in Addison's disease — insufficient fludrocortisone dosing contributes to orthostatic hypotension and salt-wasting crisis.
Safety Profile
Pregnancy use-with-caution
Lactation use-with-caution
Renal Adjustment Not required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.