questions 5

K-Sparing Diuretics

Topic updated on 10/26/17 5:15pm


  • 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


Qbank (2 Questions)

(M1.RL.13) A 70-year-old Caucasian male visits your office regularly for treatment of New York Heart association class IV congestive heart failure. Which of the following medications would you add to this man's drug regimen in order to improve his overall survival? Topic Review Topic

1. Spironolactone
2. Amiloride
3. Hydrochlorothiazide
4. Furosemide
5. Acetazolamide

(M1.RL.50) A 58-year-old man who had been complaining of increased shortness of breath with exertion and paroxysmal nocturnal dyspnea was started on a medical regimen to help stabilize his condition and relieve his fluid retention. Though his symptoms were improving, he noticed bilateral breast enlargement (Figure A) and returned to the clinic. The drug responsible for his breast enlargement also functions to do which of the following? Topic Review Topic
FIGURES: A          

1. Increase the PR interval on EKG
2. Inhibit angiotensin converting enzyme
3. Bind mineralcorticoid receptors
4. Inhibit the Na+/K+/2Cl- triple transporter in the thick ascending limb of the loop of Henle
5. Increase tubular fluid osmolarity

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