Potassium-sparing diuretics and mineralocorticoid receptor antagonists

At a glance

• Two groups act on the aldosterone-sensitive distal nephron (late distal tubule and cortical collecting duct): mineralocorticoid receptor antagonists (spironolactone, eplerenone, finerenone) and ENaC blockers (amiloride, triamterene).
• Both are weak natriuretics, because only about 2 to 3% of filtered sodium is reabsorbed here. They are used to block aldosterone's harm in heart failure, CKD, primary aldosteronism and cirrhosis, and to offset potassium loss from loop and thiazide diuretics.
• Paper 1 tests the principal cell physiology, why they cause hyperkalaemia and metabolic acidosis, selectivity and CYP3A4 differences, and RALES numbers.