Torasemide. An update of its pharmacological properties and therapeutic efficacy

The pharmacological properties and therapeutic use of the high-ceiling loop diuretic torasemide (torsemide) were previously reviewed in Drugs in 1991, the following being a re-examination of the role of the drug in the light of data that have subsequently become available (particularly in the management of oedematous disorders). Torasemide produces a more prolonged water and electrolyte excretion than equipotent diuretic doses of furosemide (frusemide), but does not increase kaliuresis to the same extent. Dosages of torasemide of 2.5 to 5 mg/day do not affect plasma renin activity or aldosterone release to a clinically significant extent, although torasemide 20mg increases plasma renin levels, angiotensin II activity and urinary dopamine and prostaglandin E excretion. Studies published since the previous review have confirmed the efficacy of low dosages of torasemide (2.5 to 5 mg/day) in the treatment of hypertension, and have shown it to be effective when administered orally at a dosage of 5 to 20 mg/day in the management of congestive heart failure. Dosages of up to 400 mg/day increased urinary volume excretion and natriuresis in patients with chronic renal failure. Bodyweight and peripheral oedema were reduced by torasemide 10 to 200 mg/day as monotherapy, and 5 to 20 mg/day when coadministered with spironolactone, in patients with nephrotic syndrome. Dosages of 10 to 40 mg/day, either as monotherapy or in conjunction with an aldosterone antagonist, reduced ascites, oedema and bodyweight in patients with hydropically decompensated liver failure. Adverse effects due to torasemide are usually mild and transient in nature. No evidence of ototoxicity has been demonstrated in humans, and torasemide does not appear to affect blood glucose levels, serum uric acid concentrations, or serum potassium levels at dosages below 5 mg/day. Thus, additional evidence has accumulated for the clinical efficacy of torasemide in the management of mild to moderate essential hypertension and oedematous conditions which require diuretic therapy. Further studies are now required to confirm the long term efficacy and tolerability of torasemide, and to investigate the place of the drug in therapy relative to cardiovascular agents other than furosemide and the thiazide diuretics.