Potassium-Sparing Diuretic

Aka: Potassium-Sparing Diuretic, Selective Aldosterone Receptor Antagonist, Selective Aldosterone Blocker, Aldosterone Antagonist

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II. Indications

  1. Potassium-Sparing Diuretics only (Aldosterone independent, Amiloride and Triamterene)
    1. Hypertension
      1. Weak Diuretics primarily used to counter urinary Potassium loss with other Diuretics
  2. Selective Aldosterone Receptor Antagonist (Spironolactone, Eplerenone)
    1. Congestive Heart Failure
      1. Counter Aldosterone adverse effects on myocardial remodeling
  3. Non-Steroidal Aldosterone Antagonist (Finerenone)
    1. Diabetic Nephropathy (Type 2 Diabetes)
      1. May limit renal fibrosis and inflammation
      2. May decrease CKD progression (in combination with ACE or ARB)
    2. Congestive Heart Failure
      1. Finerenone is FDA approved for Heart Failure with EF >40%
      2. May be used as an expensive alternative to Spironolactone or Eplerenone (but not together)
  4. Aldosterone Synthase Inhibitor
    1. Resistant Hypertension, uncontrolled by other combination therapy

III. Mechanism

  1. Potassium-Sparing Diuretics only (Amiloride, Triamterene)
    1. Weak Diuretics (compared with Loop Diuretics or Thiazide Diuretics)
    2. Primarily used to counter urinary Potassium loss with other Diuretics (e.g. Thiazide Diuretics)
    3. Act directly at the distal convoluted tubule (Aldosterone independent)
      1. nephron.png
      2. Increase Sodium excretion
      3. Decrease Potassium secretion
  2. Selective Aldosterone Receptor Antagonists (Spironolactone and Eplerenone)
    1. Commonly used as adjunctive in Congestive Heart Failure management
    2. Eplerenone is more selective for Aldosterone than Spironolactone
    3. Block Aldosterone activity at the distal convoluted tubules and collecting ducts
      1. Counter Aldosterone adverse effects on myocardial remodeling
  3. Non-Steroidal Aldosterone Antagonist (Finerenone)
    1. Similar anti-Aldosterone effects of steroidal Aldosterone Antagonists (Eplerenone, Spironolactone)
    2. Unlike Spironolactone, not associated with Gynecomastia
  4. Aldosterone Synthase Inhibitor (Baxdrostat)
    1. Inhibits Aldosterone formation by the zona glomerulosa of the Adrenal Cortex
    2. Reduced circulating Aldosterone, decreases Sodium and water retention

IV. Medications

  1. Potassium-Sparing Diuretics only (Aldosterone independent)
    1. Amiloride (Midamor)
    2. Triamterene (Dyrenium)
  2. Steroidal Aldosterone Antagonists AND Potassium-Sparing Diuretic
    1. Spironolactone (Aldactone)
    2. Eplerenone (Inspra)
  3. Nonsteroidal Aldosterone Antagonists
    1. Nonsteroidal Mineralocorticoid Receptor Antagonist (Finerenone)
  4. Aldosterone Synthase Inhibitor
    1. Baxdrostat (Baxfendy)

V. Precautions

  1. Monitor Serum Potassium after starting a Potassium-Sparing Diuretic in those at Hyperkalemia risk
    1. Obtain Serum Potassium at 3 days, 7 days and then monthly for the first 3 months

VI. Adverse Effects: Potassium-Sparing Diuretics (Amiloride and Triamterene)

  1. Hyperkalemia
    1. Risk factors
      1. Renal Insufficiency
      2. Concurrent use with agents that raise Potassium (e.g. ACE Inhibitors, Potassium supplements)
  2. Blue Urine Color
    1. Specific to Triamterene
  3. Decreased renal perfusion (if Sodium and water depletion)
  4. Glucose Intolerance
    1. Potassium-Sparing Diuretics

VII. Drug Interactions

  1. Potassium supplements (risk of Hyperkalemia)

VIII. References

  1. Olson (2020) Clinical Pharmacology, Medmaster, Miami, p. 62-3
  2. Hamilton (2010) Tarason Pocket Pharmacopeia, p. 100

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