Switching from Spironolactone to Eplerenone

Introduction to Conversion

• The European Society of Cardiology recommends a direct switch from spironolactone to eplerenone without a washout period, using a 2:1 dose conversion ratio (50 mg eplerenone = 25 mg spironolactone), with mandatory electrolyte and renal function monitoring at 1 and 4 weeks post-switch 1

Conversion Protocol

• Use a 2:1 conversion ratio: 50 mg eplerenone daily equals 25 mg spironolactone daily 1
• If the patient is on spironolactone 25 mg daily, switch to eplerenone 50 mg daily 1
• If on spironolactone 50 mg daily, switch to eplerenone 100 mg daily 1
• No washout period is required between stopping spironolactone and starting eplerenone 1

Pre-Switch Assessment

• Before making the switch, verify that serum potassium is ≤5.0 mmol/L (do not switch if >5.0 mmol/L) 1
• Verify that serum creatinine is <220 μmol/L (2.5 mg/dL) 2, 3, 4
• Verify that eGFR is >30 mL/min/1.73 m² (avoid both agents if <30) 1

Mandatory Monitoring Schedule

• Check electrolytes and renal function at 1 week post-switch 2, 3, 4
• Recheck at 4 weeks post-switch 2, 3, 4
• Continue monitoring at 1, 2, 3, and 6 months after achieving stable dose 2, 3, 4
• Then monitor every 6 months thereafter 2, 3, 4

Managing Hyperkalemia After Switch

• If potassium rises to >5.5 mmol/L: Halve the eplerenone dose (e.g., 50 mg to 25 mg, or 25 mg every other day) 2, 3, 4
• If potassium rises to >6.0 mmol/L: Stop eplerenone immediately and monitor closely; specific treatment may be needed 2, 3, 4

Critical Pitfalls to Avoid

• Do not discontinue potassium supplements abruptly without checking baseline potassium first - both drugs are potassium-sparing 1
• Do not combine with both ACE inhibitor AND ARB - this dramatically increases hyperkalemia risk 2, 3, 4
• Do not switch if baseline potassium is already >5.0 mmol/L - address hyperkalemia first 1