K-sparing diuretics

(NEJM 2017;377:1964)

• Drugs: spironolactone (Aldactone), amiloride, triamterene, eplerenone

• Mech: ↓ Na reabsorption (~1%) in collecting duct (amiloride/triamterene inhibit principal cell Na channel [ENaC]; spironolactone/eplerenone inhibit mineralocorticoid receptor).

Relatively weak natriuretic activity, useful in combination with thiazide or in cirrhosis.

• Adverse effects: ↑ K (esp. w/ ACEI), metabolic acidosis, gynecomastia (spironolactone)