spironolactone

spironolactone, diuretic drug that is used primarily to treat conditions related to edema (fluid retention), hypertension (high blood pressure), and hormone imbalances. The therapeutic effects of spironolactone were first described in the late 1950s. In 1960 the drug was approved for the treatment of hypertension.

Mechanism of action

Spironolactone exerts its effects by binding to and blocking receptors for the hormone aldosterone, which is secreted by the adrenal glands and functions to regulate sodium and water retention and potassium excretion. Inhibition of aldosterone activity results in increased excretion of sodium and water, helping to reduce blood volume and blood pressure. At the same time, this conserves potassium, which is essential for maintaining cell function, particularly in the case of muscle cells. Spironolactone also blocks androgen receptors, which reduces the synthesis of androgen hormones such as testosterone.

Uses

Spironolactone often is prescribed to treat edema associated with conditions such as cirrhosis, congestive heart failure, and nephrotic syndrome, which is a sign of kidney malfunction. It also is used in the treatment of resistant hypertension, in which blood pressure remains high despite other medications, and primary hyperaldosteronism (Conn syndrome), in which the body produces too much aldosterone.

The antiandrogen effects of spironolactone are valuable in the treatment of certain hormone imbalances. Examples include acne associated with polycystic ovary syndrome (PCOS), which causes increased oil production in the skin, and hirsutism, which is characterized by excessive hair growth because of elevated levels of androgens. Spironolactone is also used in transgender women as part of gender-affirming hormone therapy; when combined with estrogen therapy, reductions in testosterone levels induced by the drug can help facilitate the development of feminine secondary sex characteristics.

Side effects

Spironolactone is associated with various side effects, some more severe than others. Relatively mild effects include dizziness, gastrointestinal upset, gynecomastia (enlargement of breast tissue in males), headache, menstrual irregularities, and skin rashes. More severe adverse effects include hyperkalemia (elevated potassium levels), which can lead to dangerous alterations in heart rhythm, and exacerbation of preexisting diseases or disorders associated with alterations in electrolyte balance. Such adverse effects can be avoided through close monitoring of potassium levels and kidney function.