• A 63-year-old man with a history of congestive heart failure presents with increased pedal edema and worsening orthopnea. He reports that he has been taking his lisinopril as prescribed and adhering to a low-salt diet. Physical exam shows 2+ pitting edema in the knees bilaterally and faint crackles on auscultation of the lungs. Left ventricular ejection fraction (LVEF) is measured by echocardiogram and found to be 33%. This is decreased from his last measurement of 38%. He is put on an additional medication. (Congestive heart failure exacerbations)
Spironolactone and Eplerenone
  • Mechanism
    • competitive aldosterone receptor antagonist in the cortical collecting tubule
      • reduces potassium secretion by decreasing activity of the epithelial sodium channel (ENAC) and the apical potassium channel
  • Clinical use
    • hyperaldosteronism
    • potassium wasting
      • from loop or thiazide diuretics
    • congestive heart failure (CHF)
      • decreases ventricular remodeling
      • reduces mortality
    • antiandrogenic
      • treatment for female hirsutism
  • Toxicity
    • hyperkalemia
      • can result in arrhythmias
    • spironolactone has antiandrogen effects  
      • causes gynecomastia 
      • eplerenone causes gynecomastia to a lesser extent 
Triamterene and Amiloride
  • Mechanism
    • blocks ENAC in the cortical collecting duct, thereby leading to decreased sodium reabsorption
      • indirectly reduces potassium secretion by creating a more positive luminal potential
      • indirectly decreases activity of the apical proton ATPase and reduces secretion of protons
    • does not cause anti-androgen effects
  • Clinical use
    • congestive heart failure (CHF)
    • potassium wasting
    • lithium-induced nephrogenic diabetes insipidus
      • amiloride
  • Toxicity
    • hyperkalemia 
    • normal anion gap metabolic acidosis

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