What is a potential adverse interaction when potassium-sparing diuretics are used with ACE inhibitors?

• A. Hypokalemia
• B. Hyperkalemia
• C. Hyponatremia
• D. Hypocalcemia

Answer: (B)

When potassium-sparing diuretics and ACE inhibitors are combined, the main risk is hyperkalemia. Potassium-sparing diuretics either block sodium channels in the collecting duct (amiloride, triamterene) or antagonize aldosterone receptors (spironolactone, eplerenone). Both actions reduce potassium excretion in the distal nephron. ACE inhibitors decrease angiotensin II, which lowers aldosterone release from the adrenal glands. With less aldosterone, the kidneys excrete even less potassium. Put together, these drugs markedly raise potassium levels in the blood, which can lead to dangerous heart rhythm problems.

So, the best answer is hyperkalemia because this combination directly promotes potassium retention. Hypokalemia would require increased potassium loss, which these drugs do not cause; hyponatremia and hypocalcemia are not the characteristic risks of this combo. Monitor serum potassium and renal function when these drugs are used together.