Fludrocortisone
📘 About
- Always check the BNF entry for the most up-to-date prescribing advice.
- Fludrocortisone is a potent synthetic corticosteroid with strong mineralocorticoid activity and weak glucocorticoid activity.
- Used mainly for mineralocorticoid replacement and treatment of refractory postural hypotension.
⚙️ Mode of Action
- Binds to mineralocorticoid receptors in the kidney → increases Na⁺ reabsorption and K⁺/H⁺ excretion in the distal tubule.
- Results in expanded extracellular fluid volume, ↑ blood pressure, and improved vascular tone.
💊 Indications & Example Doses
- Addison’s disease (primary adrenal insufficiency): 50–300 micrograms PO daily (in addition to hydrocortisone for glucocorticoid replacement).
- Congenital adrenal hyperplasia: as above, tailored to electrolyte balance.
- Neurogenic / refractory postural hypotension: start 100 micrograms PO daily, titrate by 100 micrograms every 1–2 weeks to max 400 micrograms daily.
⚠️ Always titrate to clinical response and electrolytes. Higher doses increase risk of fluid overload and hypokalaemia.
🔀 Interactions
- See BNF for full list.
- Other corticosteroids → additive effects (fluid retention, hypertension).
- Potassium-wasting diuretics → ↑ risk of severe hypokalaemia.
- Antihypertensives → may blunt effect due to opposing mechanisms.
⚠️ Cautions
- Hypertension, heart failure, renal impairment.
- Diabetes mellitus (may worsen glycaemic control).
- Elderly (more susceptible to adverse effects).
- Monitor electrolytes and BP regularly.
🚫 Contraindications
- See BNF — generally avoid in systemic fungal infections and hypersensitivity to fludrocortisone.
💥 Side Effects
- Short-term: sodium and water retention, oedema, hypokalaemia, hypertension, headache.
- Long-term: osteoporosis, muscle weakness, immunosuppression, glucose intolerance, Cushingoid features.
📚 References
