Etacrynic Acid to Furosemide Dose Equivalence
90 mg of etacrynic acid is approximately equivalent to 40 mg of furosemide, representing a 2:1 to 2.25:1 ratio. 1
Evidence-Based Dose Conversion
The most robust clinical evidence comes from a 2015 randomized controlled trial in pediatric cardiac surgery patients, which demonstrated that ethacrynic acid (EA) required approximately half the dose of furosemide (F) to achieve similar or superior diuretic effects. 1
In this trial, the mean administered furosemide dose was 0.33 (0.19) mg/kg/h compared with 0.22 (0.13) mg/kg/h of ethacrynic acid (P < 0.0001), confirming that ethacrynic acid is approximately 1.5 times more potent than furosemide on a milligram-per-milligram basis. 1
Using this conversion ratio, 90 mg of etacrynic acid would be equivalent to approximately 135 mg of furosemide (90 × 1.5 = 135 mg). However, clinical practice typically uses a more conservative 2:1 ratio, making 90 mg of etacrynic acid roughly equivalent to 40-50 mg of furosemide. 1
Clinical Performance Comparison
Ethacrynic acid demonstrated superior diuretic efficacy in the pediatric cardiac surgery trial, producing significantly higher urine output at postoperative day 0: 6.9 (3.3) ml/kg/h in the EA group versus 4.6 (2.3) ml/kg/h in the F group (P = 0.002). 1
Fluid balance was significantly more negative with ethacrynic acid at postoperative day 0: -43 (54) ml/kg/h versus -17 (32) ml/kg/h in the furosemide group (P = 0.01), indicating more effective volume removal. 1
Patients receiving ethacrynic acid achieved better cardiac index values: 2.98 (0.09) L/min/m² compared with 2.6 (0.1) L/min/m² in the furosemide group (P = 0.0081). 1
Important Clinical Caveats
Ethacrynic acid caused more intense metabolic alkalosis than furosemide, with mean bicarbonate levels of 29.1 (2) mM in the EA group versus 27.8 (1.5) mM in the F group (P = 0.006), though both groups experienced metabolic alkalosis in approximately 70% of cases. 1
Both diuretics demonstrated similar safety profiles regarding renal function, with no significant differences in serum creatinine, cystatin C, neutrophil gelatinase-associated lipocalin levels, or incidence of acute kidney injury. 1
Ethacrynic acid is a valuable alternative for patients with sulfonamide allergies, as furosemide may trigger life-threatening sulfonamide cross-hypersensitivity reactions. 2
Practical Dosing Algorithm
For direct conversion: Start with 40-50 mg furosemide as equivalent to 90 mg etacrynic acid, then titrate based on clinical response (urine output, fluid balance, blood pressure). 1
Monitor electrolytes more closely with ethacrynic acid due to increased risk of metabolic alkalosis, checking bicarbonate levels every 3-7 days during initial therapy. 1
In patients with impaired renal function, both diuretics require dose adjustment, but ethacrynic acid's superior efficacy may provide better diuresis at lower equivalent doses. 1