What is the recommended dosage of Spironolactone for patients with heart failure or resistant hypertension?

Spironolactone Dosing in Heart Failure and Resistant Hypertension

For heart failure, spironolactone should be initiated at 12.5-25 mg once daily and titrated to a maximum of 25-50 mg daily, while for resistant hypertension, a dose of 25-50 mg daily is recommended with careful monitoring of potassium and renal function. 1, 2

Heart Failure Dosing

Initial Dosing Based on Renal Function

• eGFR >50 mL/min/1.73m²: Start at 25 mg once daily 1, 2
• eGFR 30-49 mL/min/1.73m²: Start at 25 mg every other day 1, 2
• eGFR <30 mL/min/1.73m²: Avoid use due to high risk of hyperkalemia 1

Titration

• Patients who tolerate 25 mg daily may be increased to 50 mg daily as clinically indicated 2
• If hyperkalemia develops on 25 mg daily, reduce to 25 mg every other day 3, 2
• Maximum recommended dose: 50 mg daily 3

Resistant Hypertension Dosing

• Start with 25 mg daily 4
• May increase to 50 mg daily if needed and tolerated 4
• Low-dose spironolactone (25-50 mg) has been shown to effectively reduce systolic blood pressure by approximately 21.7 mmHg in resistant hypertension 4

Monitoring Protocol

1. Before initiation: Check baseline potassium and renal function 3, 1
2. After initiation:
   • Check potassium and renal function within 3 days 3
   • Recheck at 1 week 3, 1
   • Monitor at 1 month, 2 months, 3 months 1
   • Then every 3-6 months if stable 3, 1
3. Additional monitoring:
   • After any dose adjustment 3
   • After addition or increase in ACE inhibitors or ARBs 3
   • During episodes of intercurrent illness (especially diarrhea, vomiting) 3

Cautions and Contraindications

• Avoid in patients with:

  • Baseline serum potassium >5.0 mEq/L 1
  • Severe renal dysfunction (eGFR <30 mL/min/1.73m²) 1

• Use with extreme caution in:

  • Elderly patients 1
  • Patients with diabetes 5
  • Patients on ACE inhibitors or ARBs 3, 1
  • Patients at risk for dehydration 5

Managing Adverse Effects

• Hyperkalemia (serum K+ >5.5 mEq/L):

  • Reduce dose or discontinue spironolactone 3
  • Stop potassium supplements 3
  • Evaluate entire medication regimen 3

• Worsening renal function:

  • Evaluate entire medical regimen 3
  • Consider dose reduction or discontinuation 3

• Gynecomastia:

  • Consider switching to eplerenone 25-50 mg daily 1

Common Pitfalls to Avoid

1. Inadequate monitoring: Studies show 34% of patients don't receive follow-up laboratory tests within 3 months of initiation 6
2. Triple RAAS blockade: Avoid routine triple combination of ACEIs, ARBs, and spironolactone due to high risk of hyperkalemia 3
3. Excessive dosing: Daily spironolactone doses exceeding 25 mg in patients with renal insufficiency significantly increases hyperkalemia risk 5
4. Drug interactions: NSAIDs and COX-2 inhibitors can worsen renal function and increase hyperkalemia risk when combined with spironolactone 3
5. Failure to counsel patients: Patients should be instructed to temporarily stop spironolactone during episodes of diarrhea or when loop diuretic therapy is interrupted 3

Remember that careful patient selection, appropriate dosing based on renal function, and vigilant monitoring are essential for safe and effective use of spironolactone in both heart failure and resistant hypertension.