| 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. |
| Pharmacodynamics | Furosemide, a sulfonamide-type loop diuretic structurally related to bumetanide, is used to manage hypertension and edema associated with congestive heart failure, cirrhosis, and renal disease, including the nephrotic syndrome. |
| 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. |
| Absorption | 60% absorbed in patients with normal renal function |
| Volume of distribution | Not Available |
| Protein binding | 95% bound to plasma proteins |
| Metabolism | Only a small amount is hepatically metabolized to the defurfurylated derivative, 4-chloro-5-sulfamoylanthranilic acid. |
| Route of elimination | Furosemide is excreted in urine. Significantly more furosemide is excreted in urine following the I.V. injection than after the tablet or oral solution. |
| Half life | 2 hours |
| Clearance | Not Available |
| 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. |