Spironolactone

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