Aldosterone Antagonists

Aldosterone acts through the mineralocorticoid receptor, which transactivates genes that increase sodium and water retention and potassium loss, raising extracellular fluid volume and blood pressure. Drugs in this class block that receptor: the FDA-approved label for spironolactone describes it and its active metabolites as specific pharmacologic antagonists of aldosterone acting through competitive binding at the aldosterone-dependent sodium-potassium exchange site in the distal convoluted tubule. The result is a potassium-sparing diuresis, so hyperkalaemia rather than hypokalaemia is the risk to watch.