Pharm

Potassium-Sparing Diuretic

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Potassium-Sparing Diuretic, Amiloride, Midamor, Triamterene, Dyrenium

  • Indications
  • Potassium-Sparing Diuretics only (Aldosterone independent, Amiloride and Triamterene)
  1. Hypertension
    1. Weak Diuretics primarily used to counter urinary Potassium loss with other Diuretics
  1. Congestive Heart Failure
    1. Counter Aldosterone adverse effects on myocardial remodeling
  • Mechanism
  1. Weak Diuretics (compared with Loop Diuretics or Thiazide Diuretics)
  2. Potassium-Sparing Diuretics only
    1. Primarily used to counter urinary Potassium loss with other Diuretics
    2. Act directly at the distal convoluted tubule (Aldosterone independent)
      1. Increase Sodium excretion
      2. Decrease Potassium secretion
  3. Aldosterone Antagonists (Spironolactone and Eplerenone)
    1. Commonly used as adjunctive in Congestive Heart Failure management
    2. Counter Aldosterone adverse effects on myocardial remodeling
  • Preparations
  • Potassium-Sparing Diuretics only (Aldosterone independent)
  1. Amiloride (Midamor)
    1. Dose: 5 mg orally daily (maximum: 20 mg/day)
    2. Renal excretion (unchanged in urine)
    3. Half-life: 6 hours
  2. Triamterene (Dyrenium)
    1. Dose: 100 mg orally twice daily (maximum: 300 mg/day)
    2. Typically used as Combination Medication with Thiazide Diuretic
    3. Rapidly absorbed, highly metabolized in liver and Kidney and rapidly excreted
  1. Spironolactone (Aldactone)
  2. Eplerenone (Inspra)
  • 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
  • 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
  • Drug Interactions
  1. Potassium supplements (risk of Hyperkalemia)
  • References
  1. Olson (2020) Clinical Pharmacology, Medmaster, Miami, p. 62-3
  2. Hamilton (2010) Tarason Pocket Pharmacopeia, p. 100