TORSEMIDE - A NEW LOOP DIURETIC

The pharmacology, pharmacokinetics, clinical efficacy, adverse effects , and dosage and administration of torsemide are reviewed. Torsemide b elongs to the pyridine-sulfonylurea class of loop diuretics. Its prima ry site of activity is the thick ascending limb of the loop of Henle, where it blocks active reabsorption of sodium and chloride, resulting in diuresis, natriuresis, and other effects. Torsemide has high bioava ilability, a relatively long half-life, and a prolonged duration of ac tivity. It is highly protein bound. Clinical trials indicate that tors emide is effective in the treatment of hypertension and of edema and o ther symptoms in patients with chronic renal failure (CRF), hepatic dy sfunction, or congestive heart failure (CHF). Torsemide has infrequent , mild, and transient adverse effects; among the most common are ortho static hypotension, fatigue, dizziness, and nervousness. The recommend ed initial oral dosages of torsemide are 10-20 mg/day for CHF, 20 mg/d ay for CRF, 5 mg/day for hypertension, and 5-10 mg/day (in combination with a potassium-sparing diuretic or aldosterone antagonist) for hepa tic cirrhosis. In most patients, the pharmacokinetic advantages of tor semide over other loop diuretics are unlikely to translate into a subs tantial edge in clinical outcomes, and in practice there may be no cos t advantages. Although torsemide does not offer major advantages over other loop diuretics, it may be of benefit in patients who do not resp ond to or cannot tolerate other agents.