Spironolactone

Administration

• Type: Antihypertensive; Potassium Sparing Diuretic; Aldosterone Receptor Antagonist
• Dosage Forms: 25,50,100
• Routes of Administration: Oral
• Common Trade Names: Aldactone

Adult Dosing

• Edema: 25-200 mg/day PO divided qd-bid
  • For edema assoc. with CHF, cirrhosis, or nephrotic syndrome

• HTN: 25-50 mg/day PO divided qd-bid
  • Start: 12.5 mg PO qd

• Hyperaldosteronism, primary: 100-400 mg PO qd

• Hypokalemia, diuretic-induced: 25-100 mg/day PO divided qd-qid

• CHF, NYHA Class III/IV: 25 mg PO qd
  • Use with standard tx; may incr. to 50 mg/day after 8wk for worsening CHF if K stable
  • May decr. to 25 mg qod if hyperkalemia; hold if K >5 mEq/L or Cr >4 mg/dL

• Hirsutism, idiopathic: 50-200 mg PO qd
  • Off label use

• Acne vulgaris: 50-200 mg PO qd
  • Start: 25 mg PO qd
  • Off label use

Pediatric Dosing

• Edema: 1-3.3 mg/kg/day PO divided qd-qid
  • Max: 3.3 mg/kg/day up to 200 mg/day
  • Off label use

• Hyperaldosteronism test: 125-375 mg/m^2/day PO divided bid-qid
  • Max: 375 mg/m^2/day
  • Off label use

Special Populations

• Pregnancy Risk Factor: C

Renal Dosing

• CrCl <10, anuria, or acute renal impairment: contraindicated

Hepatic Dosing

• Caution advised with hepatic impairment

Contraindications

• Allergy to class/drug
• CrCl <10
• anuria
• renal impairment, acute
• hyperkalemia
• Addison disease

Adverse Reactions

Serious

• anaphylaxis
• Stevens-Johnson syndrome
• toxic epidermal necrolysis
• drug reaction with eosinophilia and systemic sx
• vasculitis
• hepatotoxicity
• renal failure
• electrolyte imbalance
• hyperkalemia, severe
• arrhythmias
• leukopenia
• agranulocytosis
• thrombocytopenia

Common

• nausea/vomiting
• abdominal cramps/pain
• muscle cramps
• diarrhea
• headache
• confusion
• dizziness
• somnolence

Pharmacology

• Half-life: 1.3-2h (parent drug), 13.8-16.5h (active metabolites)
• Metabolism: Liver
• Excretion: Urine

Mechanism of Action

Antagonizes aldosterone receptors in the distal convoluted tubule, decreasing Na and water reabsorption and increasing K retention

References

<Epocrates, UpToDate>