Medicine & USMLE

Ethacrynic Acid

Renal Pharm
  1. ACE Inhibitors
  2. Aldosterone Receptor Blockers (Spironolactone, Eplerenone)
  3. Ethacrynic Acid
  4. Loop Diuretics (Furosemide, Bumetanide, Torsemide)
  5. Mannitol
  6. Acetazolamide
  7. ENaC Blockers (Amiloride, Triamterene)
  8. Thiazide Diuretics
  9. Angiotensin II Receptor Blockers (ARBs)


Ethacrynic acid is a type of loop diuretic. Like all loop diuretics, it works by inhibiting the sodium-potassium-chloride cotransporter in the ascending loop of henle to induce diuresis. The net effect of ethacrynic acid is increased excretion of water, sodium, and potassium. It also causes an increase in calcium and magnesium excretion.

Ethacynic acid has nearly identical clinical uses to other loop diuretics. However, because they do not contain the sulfonamide groups generally found in other diuretics, ethacrynic acid is particularly good for treatment of patients with sulfa allergies.

However, there are a few adverse effects of ethacrynic acid. Firstly, because ethacrynic acid can interfere with ion balance within the ear, it is ototoxic and can cause hearing loss or tinnitus. Secondly, ethacrynic acid can cause hyperuricemia, leading to gout.

Key Points

  • Ethacrynic Acid
    • Mechanism:
      • Loop diuretic
        • Blocks Na+/K+/2Cl- cotransporters
        • Thick ascending loop of Henle
        • ↑ excretion of Ca2+, Mg2+
        • ↑ excretion of Na+/K+
    • Indications:
      • Diuresis in patients with sulfa allergies
        • Sulfa drug diuretics include thiazides, furosemide, bumetanide, torsemide, and acetazolamide
    • Adverse effects:
      • Ototoxic (more ototoxic than furosemide)
        • Risk worsened with concomitant aminoglycoside use
      • Hyperuricemia/gout