Ethacrynic acid (
Edecrin) is a loop
diuretic that produces a prompt and profound diuresis. The primary action of
ethacrynic acid is the inhibition of the activity of the Na⁺-K⁺-2Cl⁻
symporter in the thick ascending limb of the loop of Henle. The onset of action is usually within 30 minutes after an oral dose and within 5 minutes after an
intravenous injection. After
oral administration, peak
diuretic effect occurs in about 2 hours and the effect lasts about 6-8 hours. After
intravenous administration, peak
diuretic effect occurs within 30 minutes and the
diuretic effect is virtually completed in 2-4 hours. The bioavailability of
ethacrynic acid approximates 100%, with maximal blood level between 40 and 92 minutes. The elimination half-life has been reported to be less than 1 hour, but highly variable (average 30 minutes with a range of 12-160 minutes). Intravenous
ethacrynic acid has a prompt venous dilatory effect and immediately relieves symptoms of pulmonary congestion, before a diuresis can occur.
Ethacrynic acid is effective in all types of
edema whether there is clinical
acidosis,
alkalosis, or
electrolyte imbalance. Most side effects of
ethacrynic acid can be attributed to its effectiveness (volume depletion); however, it may cause metabolic
alkalosis that is preventable by KCl replacement.
Ethacrynic acid has ototoxic effect that occasionally results in temporally or
permanent deafness. Despite limitations,
ethacrynic acid has been employed in the treatment of
congestive heart failure and other edematous states, especially in patients allergic to sulfa-containing drugs because all the other
loop diuretics have a sulfa moiety.