USMLE

Spironolactone

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Cardiovascular Drugs
  1. Beta Blockers
  2. ACE Inhibitors
  3. Angiotensin II Receptor Blockers (ARBs)
  4. Adenosine
  5. Atropine
  6. Amiodarone
  7. DHP Calcium Channel Blockers
  8. Non-DHP Calcium Channel Blockers
  9. Clonidine
  10. Clopidogrel
  11. Digoxin
  12. Dopamine
  13. Epinephrine
  14. Hydralazine
  15. Loop Diuretics
  16. Nitroglycerin
  17. Norepinephrine
  18. Spironolactone
  19. Statins
  20. Thiazide Diuretics

Summary

Spironolactone is a diuretic that is used to remove excess fluid. By reducing blood volume, it can be effective in treating edema and hypertension. Importantly, spironolactone is a potassium-sparing diuretic, meaning that it increases potassium levels in the body and may even cause hyperkalemia at high doses, so you’ll want to keep a close eye on electrolyte levels. Since spironolactone causes fluid loss by way of urination, you’ll want to monitor the patient’s urine output, kidney function, and daily weights.

Key Points

  • Mechanism
    • Removes excess fluid (diuresis)
      • Aldosterone receptor antagonist
        • Blocks aldosterone and inhibits the sodium-potassium pump
      • Promotes sodium and water excretion and potassium retention at the distal tubule and collecting duct
        • Potassium-sparing diuretic
      • Relatively weak compared to other diuretics
    • Clinical Use
      • Hypertension
        • Decreased fluid volume = lower BP
        • Potassium-sparing diuretics are very weak diuretics, and are usually combined with other diuretics for the purposes of reducing potassium loss
      • Edema
        • Heart Failure
          • Spironolactone is the diuretic of choice for heart failure, as it has been proven to greatly reduce mortality
        • Ascites
          • Secondary to cirrhosis
      • Will lead to increased urination
        • Contraindicated in patients with renal failure
        • Watch for signs and symptoms of dehydration
        • Closely monitor intake and output as well as BUN and creatinine
        • Take in the morning to prevent nocturia
        • Record daily weights - sudden weight gain is usually due to fluid retention
      • Hypokalemia
        • Spironolactone is a very weak diuretic and is usually combined with other diuretics (e.g. thiazide, loop) to reduce potassium loss
      • High aldosterone levels
    • Side Effects and Adverse Reactions
      • Hyperkalemia
        • ACE inhibitors and ARBs also retain potassium and this combination can result in life-threatening hyperkalemia
        • Monitoring potassium levels is essential
        • Potassium supplements should be discontinued and potassium-rich foods should be avoided
      • GI distress
        • Take with food to decrease GI side effects
      • Endocrine effects
        • Gynecomastia, menstrual irregularities, erectile dysfunction, hirsutis
        • Not a perfect aldosterone-receptor blocker; off-target blockade of testosterone and androgen receptors inhibits the action of testosterone
      • Photosensitivity