💊 Fludrocortisone

Fludrocortisone is a synthetic corticosteroid with potent mineralocorticoid activity and some glucocorticoid activity. It is primarily used for its mineralocorticoid effects.

Fludrocortisone acts on mineralocorticoid receptors in the renal tubules, increasing sodium reabsorption and potassium and hydrogen ion excretion. This leads to fluid retention and an increase in blood pressure, mimicking the action of aldosterone.

Fludrocortisone is primarily used for replacement therapy in primary adrenal insufficiency (Addison's disease) to compensate for aldosterone deficiency. It is also used in conditions with mineralocorticoid deficiency, such as congenital adrenal hyperplasia, and sometimes in orthostatic hypotension.

Absolute contraindications include systemic fungal infections (unless treated) and hypersensitivity. Relative contraindications include congestive heart failure, hypertension, and oedema, where its fluid-retaining properties could exacerbate these conditions.

Common adverse effects are related to its mineralocorticoid activity, including fluid retention, oedema, hypertension, and hypokalaemia. Less commonly, it can cause muscle weakness, headache, and gastrointestinal upset. Its glucocorticoid effects can contribute to hyperglycaemia and adrenal suppression, though less pronounced than with pure glucocorticoids.

Regular monitoring of blood pressure, serum electrolytes (especially sodium and potassium), and fluid balance is essential. Clinical assessment for signs of oedema or heart failure is also important. In Addison's disease, dosage is often titrated based on clinical response and electrolyte levels.

Check for known allergies. Be aware of drug interactions, particularly with diuretics (may exacerbate hypokalaemia), and drugs affecting potassium levels. Counsel patients on the importance of regular blood pressure and electrolyte monitoring, and to report signs of fluid retention or muscle weakness. Emphasise that it is part of a replacement regimen, not a standalone treatment for Addison's.

Fludrocortisone is crucial for mineralocorticoid replacement in Addison's disease. Remember its primary role is to regulate salt and water balance, distinct from the anti-inflammatory effects of other corticosteroids. Monitor for hypertension and hypokalaemia. It is typically co-prescribed with a glucocorticoid like hydrocortisone in adrenal insufficiency.

SBAs often test the specific role of fludrocortisone in adrenal insufficiency, particularly distinguishing it from glucocorticoid replacement (hydrocortisone). Questions may focus on identifying signs of mineralocorticoid deficiency (e.g., postural hypotension, hyponatraemia, hyperkalaemia) and the adverse effects related to its mineralocorticoid activity, such as hypertension or hypokalaemia.