A patient with hypertension and chronic kidney disease (CKD stage 3) is on maximum tolerated dose of ACE inhibitor. An aldosterone breakthrough phenomenon occurs. Which drug, when added, addresses this specifically by antagonizing the mineralocorticoid receptor?
- A Amiloride
- B Spironolactone ✓
- C Triamterene
- D Furosemide
Explanation
Aldosterone breakthrough refers to the phenomenon where serum aldosterone levels return to or exceed pre-ACEi levels despite continued ACE inhibitor therapy, occurring in up to 50% of patients over time due to non-ACE pathways (e.g., chymase) and adrenal adaptation. Spironolactone (and eplerenone) are mineralocorticoid receptor antagonists that directly block aldosterone's renal and cardiovascular effects regardless of how aldosterone is produced. Amiloride and triamterene block ENaC channels downstream of aldosterone but are not mineralocorticoid receptor antagonists. Furosemide blocks NKCC2 in the loop of Henle.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
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