Pharmacokinetic and pharmacodynamic effects of furosemide in patients with impaired renal function.

Three groups of patients with kidney diseases were investigated: I. creatinine in serum less than 100 mumol/l, II. creatinine in serum 100-250 mumol/l, III. creatinine in serum greater than 250 mumol/l. After intravenous injection of 40 mg and 80 mg furosemide, serum concentrations and urinary excretion of the unchanged drug were measured fluorometrically. Moreover, urinary excretion of water, electrolytes, creatinine and urea nitrogen were estimated in order to check the pharmacodynamic effect of the drug. The pharmacokinetic parameters calculated were similar in group I and II. In group III t 1/2 was prolonged, renal clearance of furosemide was diminished. The diuretic effect of furosemide was noticeable during the first 4 hours following the injection of 40 mg in all 3 groups. Doubling the dose did not enhance the effect. Creatinine and urea nitrogen excretion in urine were not influenced by furosemide.