Loop diuretics

Loop diuretics

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Loop diuretics (frusemide, bumetanide and ethacrynic acid) inhibit chloride-coupled sodium/potassium absorption in the ascending limb of the loop of Henle. This process accounts for retention of up to 20% of filtered sodium. Loop diuretics retain activity in renal impairment when given in higher than usual dose. All presently available loop diuretics have a short duration of action. They promote excretion of potassium and calcium as well as sodium.

Hypovolaemia and prerenal uraemia result from excessive doses of loop diuretics. Hypokalaemia is frequent, and hyponatraemia is a serious potential complication. Other adverse effects include metabolic alkalosis, hyperuricaemia, hyperglycaemia, rashes, cytopenias, other presumed hypersensitivity reactions, and tinnitus, vertigo and deafness (particularly with rapid intravenous administration). Ethacrynic acid can be used in patients allergic to frusemide and bumetanide, but it has a greater risk of ototoxicity and other adverse effects.