In a randomized double-blind trial we compared the effects of torasemide, a new loop diuretic, and furosemide in nonazotemic cirrhotic patients with ascites during a 3-day period in association with potassium canrenoate (200 mg/day) administration. Doses of loop diuretics administered in this trial (10 and 25 mg/day of torasemide and furosemide, respectively) had been shown to be equipotent in healthy subjects. Torasemide induced significantly greater natriuresis than furosemide (p less than 0.02), with a twofold greater percentage increase in basal values (day 1: 130% vs. 50%; day 2: 104% vs. 42%; and day 3: 65% vs. 26%, respectively). Body weight loss was significantly higher during torasemide (p less than 0.02) administration, and the overall decrease at the end of the treatment was twice as high for furosemide (2.5 +/- 0.6 kg vs. 1.3 +/- 0.4 kg, respectively). Diuresis was also higher during torasemide administration, but the difference was not significant (p = 0.08). The extent of kaliuresis observed during the two treatments was almost identical despite the striking differences in the natriuretic response. The effects of the two treatments on plasma electrolytes, creatinine clearance, blood urea nitrogen, mean arterial pressure, heart rate and plasma arginine vasopressin concentration were similar. Both drugs caused increases in plasma renin activity at the end of the treatment, whereas plasma aldosterone concentration slightly increased only after torasemide administration. Despite the presence of a trend toward a more pronounced effect on these parameters after torasemide administration, no significant difference between the two treatments was observed.(ABSTRACT TRUNCATED AT 250 WORDS)