Imidazole-salicylate is a non-steroidal anti-inflammatory drug with limited inhibitory effects on prostaglandin synthesis. The renal effects of this drug were investigated by a double-blind cross-over study in 10 patients with cirrhosis and ascites. Two therapeutic doses of imidazole-salicylate (750 mg each) were given at midnight and 08:00 h and 80 mg of furosemide were injected intravenously at 09:00 h. The same procedure was followed on another day but a placebo replaced imidazole-salicylate. Renal function (creatinine clearance, free water and electrolyte excretions) and urinary excretion of prostaglandin E, 6-keto-prostaglandin F1 alpha and thromboxane B2 were evaluated for 8 h after the first dose of the drug and for 2 h after furosemide injection. Platelet thromboxane production was also determined 9 h after the first administration of drug or placebo. Imidazole-salicylate did not affect renal function or inhibit kidney prostanoid production either under basal conditions or after the stimulating effect of furosemide. On the contrary, imidazole-salicylate significantly inhibited platelet thromboxane production (45.8 +/- 9 vs. 69.4 +/- 7.5 ng/ml, P < 0.05). These results suggest that imidazole-salicylate is an anti-inflammatory drug that can be given to patients with decompensated cirrhosis without risk of inhibiting kidney prostaglandin synthesis or the renal response to furosemide.