II. Indications

III. Contraindications

  1. Anuria
  2. Renal Insufficiency with Serum Creatinine over 2.4 mg/dl (GFR <30 ml/minute/1.73m2)
  3. Hyperkalemia (Serum Potassium >5 meq/L)

IV. Mechanism

  1. Potassium-Sparing Diuretic via Aldosterone blockade
    1. Spironolactone is a Aldosterone competitive inhibitor
    2. Acts at distal convoluted renal tubule
  2. Congestive Heart Failure
    1. Works synergistically with ACE Inhibitors in CHF
    2. ACE Inhibitors block Angiotensin II production
      1. Renal response is to increase Aldosterone
      2. Spironolactone blocks Aldosterone escape

V. Drug Interactions

  1. P-Glycoprotein Inhibitor
  2. Increased Serum Potassium (Hyperkalemia risk)
    1. Potassium Supplementation
    2. NSAIDs
    3. ACE Inhibitor
    4. Trimethoprim-Sulfamethoxazole
  3. Salicylates
    1. Decrease Spironolactone effect
  4. Digoxin
    1. Increased Digoxin Toxicity risk via increased Digoxin half life
  5. Norepinephrine
    1. Decreases NorepinephrineVasopressor activity

VI. Dosing

  1. Congestive Heart Failure
    1. Start 12.5 mg orally daily
    2. May increase to 25 mg orally daily after 4 weeks (up to 50 mg, but increased risk of Hyperkalemia)
    3. Monitor Serum Potassium at 3 days, 7 days and then monthly for the first 3 months
  2. Edema
    1. Dose: 50 to 100 mg orally per day divided once to twice daily
    2. Maximum: 200 mg/day
  3. Hyperandrogenism
    1. Dose: 50 mg orally twice daily
  4. Hypertension
    1. Dose: 12.5 to 50 mg orally daily
    2. Maximum: 100 mg
  5. Primary Hyperaldosteronism
    1. Dose: 100 to 400 mg/day preoperatively
    2. Use the lowest effective dose

VIII. Pharmacokinetics

  1. Liver metabolism to active metabolite (canrenone)
  2. Primarily renal excretion
  3. Half-Life: 14 to 16 hours (up to 24-36 hours)
  4. Duration: 2 to 3 days

X. Safety

  1. Pregnancy Category C
  2. Safe in Lactation

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Related Studies

Cost: Medications

spironolactone (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
SPIRONOLACTONE 100 MG TABLET Generic $0.18 each
SPIRONOLACTONE 25 MG TABLET Generic $0.05 each
SPIRONOLACTONE 50 MG TABLET Generic $0.10 each
SPIRONOLACTONE-HYDROCHLOROTHIAZIDE 25-25 TAB Generic $0.58 each