💊 Spironolactone

Potassium-Sparing Diuretic / Aldosterone Antagonist
Generic Name Spironolactone
Drug Class Potassium-Sparing Diuretic / Aldosterone Antagonist
Indications
  • Edema due to heart failure, cirrhosis, or nephrotic syndrome
  • Hypertension (adjunct therapy)
  • Primary hyperaldosteronism
  • Hypokalemia prevention
  • Acne / hirsutism (off-label, hormonal)
Mechanism of Action Competitive antagonist of aldosterone in distal renal tubules → promotes sodium and water excretion while conserving potassium and hydrogen ions.
Available Forms & Strengths • Tablet: 25 mg, 50 mg, 100 mg
• Oral suspension
Dosage Adults: 25–100 mg/day in 1–2 divided doses
Children: 1–3 mg/kg/day (specialist advice)
Route Oral
Common Side Effects
  • Hyperkalemia
  • Gynecomastia / breast tenderness
  • Menstrual irregularities
  • Dizziness
  • Gastrointestinal upset
Serious Adverse Effects Severe hyperkalemia, renal failure, arrhythmias, Stevens-Johnson syndrome (rare)
Contraindications • Hyperkalemia
• Severe renal impairment / anuria
• Addison's disease
• Hypersensitivity to spironolactone
Precautions • Monitor serum potassium
• Hepatic disease (risk of encephalopathy)
• Heart failure
• Pregnancy and lactation: use only if needed
Drug Interactions • ACE inhibitors / ARBs (↑ hyperkalemia risk)
• Potassium supplements
• NSAIDs (↓ diuretic effect)
• Digoxin (arrhythmia risk)
Pregnancy & Lactation Pregnancy: Only if benefit outweighs risk
Lactation: Use with caution
Storage Store below 30°C, protect from moisture
References BNF | BNF for Children | Goodman & Gilman
⚠️ Clinical note: Monitor potassium and renal function regularly; caution in elderly and patients on ACE inhibitors or ARBs.
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