Fludrocortisone

Fludrocortisone is a synthetic corticosteroid with moderate glucocorticoid potency and much greater mineralocorticoid potency. It is used primarily to replace the missing hormone aldosterone in various forms of adrenal insufficiency such as Addison's disease and the classic salt wasting (21-hydroxylase deficiency) form of congenital adrenal hyperplasia. It is the first line of treatment for orthostatic intolerance as well.

The brand name in the U.S. is Florinef. It is available in 0.1 mg tablets. Typical daily doses for mineralocorticoid replacement are between 0.05 mg - 0.2 mg. Renin plasma, sodium, and potassium is checked through blood tests in order to verify that the correct dosage is reached.

Chemically, its structure is identical to cortisone except for the substitution of fluorine in place of one hydrogen. Fluorine is a good bioisostere for hydrogen because it is similar in size. The major difference is in its electronegativity.