Singapore Drugs Database

Indication

For the treatment of edema associated with congestive heart failure, cirrhosis of the liver, and renal disease, including the nephrotic syndrome. Also for the treatment of hypertension alone or in combination with other antihypertensive agents.

Mechanism of Action

Furosemide, a loop diuretic, inhibits water reabsorption in the nephron by blocking the sodium-potassium-chloride cotransporter (NKCC2) in the thick ascending limb of the loop of Henle. This is achieved through competitive inhibition at the chloride binding site on the cotransporter, thus preventing the transport of sodium from the lumen of the loop of Henle into the basolateral interstitium. Consequently, the lumen becomes more hypertonic while the interstitium becomes less hypertonic, which in turn diminishes the osmotic gradient for water reabsorption throughout the nephron. Because the thick ascending limb is responsible for 25% of sodium reabsorption in the nephron, furosemide is a very potent diuretic.

Pharmacokinetics

Absorption

60% absorbed in patients with normal renal function

Distribution

Metabolism

Only a small amount is hepatically metabolized to the defurfurylated derivative, 4-chloro-5-sulfamoylanthranilic acid.

Elimination

Toxicity

Profound diuresis may cause fluid and electrolyte depletion. Excessive dehydration and potassium depletion may occur. Excessive diuresis may cause rapid weight loss, orthostatic hypotension or acute hypotensive episodes. May also cause tinnitus, reversible or permanent hearing loss or reversible deafness.

Active Ingredient/Synonyms

2-Furfurylamino-4-chloro-5-sulfamoylbenzoic acid | 4-Chloro-5-sulfamoyl-N-furfuryl-anthranilic acid | 4-Chloro-N-(2-furylmethyl)-5-sulfamoylanthranilic acid | 4-Chloro-N-furfuryl-5-sulfamoylanthranilic acid | Frusemide | Furosemid | Furosemida | Furosemide | Furosemidu | Furosemidum | Lasix (tn) | Furosemide |