Acute and Long Term Effects of Loop Diuretics in Heart Failure

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Abstract
Diuretics, together with digitalis glycosides and vasodilators are of prime importance in the medical treatment of patients with congestive heart failure (CHF). Diuretics provide quick symptomatic relief in these patients. Their beneficial effect is related to the promotion of sodium and water excretion via the kidney, thus reducing extracellular fluid volume expansion and mitigating the increase in preload and afterload caused by sodium and water retention. Loop diuretics administered intravenously are indispensable in the management of pulmonary oedema; thiazides and loop diuretics in low doses are effectively used in the oral treatment of mild to moderate heart failure. Torasemide is a new loop diuretic which differs from furosemide (frusemide) and related loop diuretics by virtue of its longer elimination half-life and longer duration of action, with almost complete bioavailability. The efficacy and tolerability of torasemide have been compared with furosemide in several studies. Once daily oral administration of torasemide (starting with 5mg) or furosemide 40mg reduce bodyweight, oedema and symptoms of heart failure to a similar extent. Mean New York Heart Association class is consistently reduced by 0.5 to 0.7. Intravenous administration attenuates the increase in intracardiac pressures during exercise in patients with CHF, and produces acute improvements in cardiac haemodynamics in patients with high grade left heart failure. A beneficial effect on both pulmonary and cardiac haemodynamics has been demonstrated during chronic oral treatment of patients with previously untreated CHF. Torasemide was well tolerated with only mild and transient adverse effects reported in a small number of patients. At standard dosages of 5 to 10mg daiiy, changes in serum electrolytes, especially potassium, are small. No clinically significant changes in metabolic parameters were seen during chronic administration for up to 48 weeks, while sustained symptomatic improvement was observed. Based on its pharmacological profile, and on its efficacy and safety, torasemide appears to be a promising and useful alternative to furosemide in the treatment of patients with CHF.