Torasemide is a loop diuretic drug, administered orally or intravenously to treat hypertension and edema associated with heart failure, renal failure, or liver disease. It targets the nephrons of the kidney, mainly the ascending limb of the loop of henle. The basolateral membrane of the ascending loop of henle contains the Na+/K+ ATPase, Cl- channel and K+/Cl- co-transporter which are essential for the function for ion and water reabsorption. The Na+/K+ ATPase pumps Na+ from the cell into the peritubular fluid and K+ from the peritubular fluid into the cell. The K+/Cl- co-transporter moves K+ and Cl- from the cell into the peritubular fluid and the Cl- channel transports Cl- from the cell into the peritubular fluid. The apical membrane contains the Na+/K+/2Cl- co-transporter (NKCC2) and the K+ channel. The NCKCC2 is responsible for reabsorption Na+, K+ and Cl- from the lumen into the cells of the loop of henle. The K+ channel transports K+ from the cells back into the lumen. Torasemide is transported from the capillaries into the cells of the loop of henle then transported from the cell into the lumen. Torasemide binds to NKCC2 transporter and inhibits it, preventing Na+, K+ and Cl- reabsorption from the lumen. The concentration of these ions builds up in the lumen, decreasing the slope of the concentration gradient between the cells and the lumen. Since water reabsorption is linked to ion reabsorption, water reabsorption is also decreased, resulting in a greater volume of water being excreted in urine. This is relieves symptoms such as swelling/ edema in patients. Side effects frequent urination, headache, cough, sore throat, hearing loss, ringing in your ears, upset stomach, constipation, diarrhea, weakness and excessive thirst may occur when taking torasemide.

Torasemide Pathway (New) References