What is the appropriate dosage and usage of Spironolactone (a potassium-sparing diuretic) for patients?

Appropriate Dosage and Usage of Spironolactone

For patients with heart failure, spironolactone should be initiated at 25 mg once daily or on alternate days, with a target dose of 25-50 mg once daily, requiring careful monitoring of potassium and renal function throughout treatment. 1

Indications and Dosing

Heart Failure

• Starting dose: 25 mg once daily (or 25 mg every other day in patients with eGFR 30-50 mL/min/1.73m²) 2
• Target dose: 25-50 mg once daily 1
• Maximum dose: 50 mg daily for heart failure 1, 2

Hypertension

• Starting dose: 25 mg daily 2
• Usual range: 25-100 mg daily 2
• For resistant hypertension: Low-dose spironolactone (25 mg) is highly effective as add-on therapy 3, 4
• Very low dose option: Even 12.5 mg daily can be effective in combination therapy for hypertension 5

Edema

• Starting dose: 25-100 mg daily 2
• Range: 25-200 mg daily 2
• For cirrhosis: Initiate in hospital setting and titrate slowly 2

Monitoring Protocol

Initial Monitoring

1. Check baseline renal function and serum electrolytes before starting 1
2. Recheck renal function and serum electrolytes at:
   • 1 week after starting 1
   • 4 weeks after starting 1
   • After any dose adjustment 1

Long-term Monitoring

• Check at 1,4,8, and 12 weeks; then at 6,9, and 12 months; then every 6 months thereafter 1
• More frequent monitoring (every 5-7 days) until potassium values stabilize after dose changes 1

Dose Adjustment Based on Laboratory Values

Hyperkalemia Management

• If K+ rises to 5.5-6.0 mmol/L: Reduce dose to 25 mg on alternate days 1
• If K+ rises to >6.0 mmol/L: Stop spironolactone immediately 1

Renal Function

• If creatinine rises to >221 μmol/L (2.5 mg/dL): Reduce dose to 25 mg on alternate days 1
• If creatinine rises to >310 μmol/L (3.5 mg/dL): Stop spironolactone immediately 1

Special Considerations and Precautions

High-Risk Populations

• Elderly patients: Typically require lower doses (median ~20 mg/day) 6
• Renal dysfunction: For eGFR 30-50 mL/min/1.73m², start at 25 mg every other day 2
• Patients with potassium >4.5 mmol/L: Consider lower doses (median ~20 mg/day) 6
• CKD patients: Even in moderate CKD (GFR 25-50 mL/min), low-dose spironolactone can be effective for resistant hypertension with careful monitoring 7

Drug Interactions to Monitor

1. ACE inhibitors and ARBs (increased risk of hyperkalemia) 1
2. Other potassium-sparing diuretics (additive hyperkalemia risk) 1
3. Potassium supplements (avoid concurrent use if possible) 1
4. NSAIDs (increased risk of renal dysfunction and hyperkalemia) 1

Common Side Effects

• Hyperkalemia (most serious concern) 1
• Gynecomastia or breast discomfort in men (occurs in ~10% of male patients) 1, 4
• Worsening renal function 1

Important Clinical Pearls

• The triple combination of ACE inhibitors, ARBs, and spironolactone should generally be avoided due to high hyperkalemia risk 1
• Patients should temporarily stop spironolactone if they develop diarrhea or vomiting 1
• Advise patients to avoid high-potassium foods and "low salt" substitutes which often contain high potassium 1, 8
• In patients unable to tolerate target doses, a low-dose strategy (even 12.5 mg) is preferable to discontinuation 6, 5
• For heart failure patients, spironolactone has been shown to increase survival, reduce hospital admissions, and improve NYHA class 1

By following these dosing guidelines and monitoring protocols, spironolactone can be used effectively while minimizing the risk of adverse effects, particularly hyperkalemia and renal dysfunction.