TORSEMIDE ACTS FROM WITHIN THE LUMEN OF THE THICK ASCENDING PORTION OF THE LOOP OF HENLE, WHERE IT INHIBITS THE NA + /K + /2CL - -CARRIER SYSTEM. CLINICAL PHARMACOLOGY STUDIES HAVE CONFIRMED THIS SITE OF ACTION IN HUMANS, AND EFFECTS IN OTHER SEGMENTS OF THE NEPHRON HAVE NOT BEEN DEMONSTRATED. TORSEMIDE INCREASES THE URINARY EXCRETION OF SODIUM, CHLORIDE, AND WATER, BUT IT DOES NOT SIGNIFICANTLY ALTER GLOMERULAR FILTRATION RATE, RENAL PLASMA FLOW, OR ACID-BASE BALANCE. DIURETIC EFFECT STARTS WITHIN 10 MTS OF I.V. ADMINISTRATION & PEAK WITHIN 1 HR & IN ORAL USE ACTION STARTS IN ONE HR & PEAKS IN 1-2 HRS LASTING FOR 6-8 HRS IN BOTH CASES.