Conversion of Eplerenone to Spironolactone
When converting from eplerenone to spironolactone, use a 2:1 ratio, with 50 mg of eplerenone being equivalent to 25 mg of spironolactone. 1
Dosing Equivalence
- The standard maintenance dose of eplerenone 50-100 mg once daily is equivalent to spironolactone 25-50 mg once daily 1
- For patients previously on eplerenone 25 mg daily, convert to spironolactone 12.5 mg daily 1
- For patients previously on eplerenone 50 mg daily, convert to spironolactone 25 mg daily 1
- For patients previously on eplerenone 100 mg daily, convert to spironolactone 50 mg daily 1
Monitoring Requirements After Conversion
- Check renal function and serum electrolytes before initiating spironolactone 2
- Recheck renal function and electrolytes at 1 and 4 weeks after conversion 2
- Continue monitoring at 1,2,3, and 6 months after achieving maintenance dose, then every 6 months thereafter 2
Side Effect Considerations
- Be aware that spironolactone has a higher incidence of endocrine side effects compared to eplerenone 1, 3
- Spironolactone causes breast discomfort and enlargement in approximately 10% of male patients compared to minimal occurrence with eplerenone 2
- Both medications carry similar risks of hyperkalemia and renal dysfunction 1, 3
Precautions When Converting
- Avoid spironolactone in patients with:
- For patients with moderate renal impairment (eGFR 30-49 mL/min/1.73 m²), reduce the starting dose to 12.5-25 mg once daily 1
- Monitor for hyperkalemia - if potassium rises to >5.5 mmol/L, halve the dose of spironolactone 2
- If potassium rises to >6.0 mmol/L, stop spironolactone immediately 2
Clinical Pearls
- Spironolactone is more potent but less selective than eplerenone 3
- The conversion maintains clinical efficacy - both medications have similar effectiveness in blood pressure reduction and heart failure management 3, 4
- Consider patient-specific factors when converting, such as sex (males more prone to gynecomastia with spironolactone) and renal function 2