Spironolacton

Spironolactone, also spelled spironolacton in some languages and sold under brand names such as Aldactone, is a potassium-sparing diuretic that acts as an antagonist of the mineralocorticoid receptor. By blocking aldosterone in the distal nephron, it decreases sodium reabsorption and potassium loss, producing diuresis with retention of potassium.

Common indications include edema associated with heart failure, liver cirrhosis, or nephrotic syndrome, and hypertension. It is also used in conditions of excess aldosterone production, such as primary hyperaldosteronism. In addition, spironolactone has antiandrogen properties and is used off-label for conditions such as hirsutism or acne in women and, in some cases, polycystic ovary syndrome, with monitoring for hormonal effects.

Pharmacokinetics are characterized by oral absorption and hepatic metabolism to active and inactive metabolites, with effects taking several days to become evident. Excretion is mainly via the urine, with activity prolonged by metabolites.

Adverse effects can include hyperkalemia, especially in patients with renal impairment or those taking potassium supplements or other potassium-sparing drugs. Other potential effects include gynecomastia, breast tenderness, menstrual irregularities, dehydration, gastrointestinal upset, and rare rash or hypersensitivity reactions. Spironolactone is generally avoided during pregnancy due to potential effects on fetal development; caution is advised in hepatic or renal impairment, and potassium/renal function should be monitored during use.

Interactions of note include other potassium-sparing agents, ACE inhibitors, ARBs, NSAIDs, and potassium supplements, which can increase the risk of hyperkalemia.