Which agent is an example of a mineralocorticoid?

Fludrocortisone is a synthetic mineralocorticoid that plays a vital role in the regulation of electrolyte and fluid balance in the body. Mineralocorticoids primarily act on the renal tubules to promote sodium retention, potassium excretion, and water reabsorption, which is crucial for maintaining blood pressure and fluid homeostasis. Fludrocortisone is specifically indicated for conditions like adrenal insufficiency and orthostatic hypotension, where increased sodium retention is beneficial. Its mechanism of action makes it distinct from glucocorticoids, which primarily exert anti-inflammatory effects and influence carbohydrate metabolism.

In contrast, the other agents listed are synthetic corticosteroids but primarily function as glucocorticoids. Beclomethasone and flunisolide are used mainly for their anti-inflammatory properties in asthma and allergic conditions, while dexamethasone is often used for its potent anti-inflammatory and immunosuppressant effects in various medical conditions. None of these agents possess the same mineralocorticoid activity as fludrocortisone, reinforcing why it is the correct answer in the context of mineralocorticoid agents.