Spironolactone is a potassium-sparing diuretic that antagonises aldosterone receptors, promoting sodium excretion while conserving potassium. It is clinically significant for managing conditions like heart failure, hypertension, and certain types of oedema, particularly in patients at risk of hypokalaemia. A key association is its use in treating primary hyperaldosteronism, where it helps mitigate symptoms and complications such as hypertension and hypokalaemia-related arrhythmias.