Clinical pharmacokinetics of furosemide in children with nephrotic syndrome.

The pharmacokinetic disposition of furosemide has been investigated in seven children with nephrotic syndrome and in eight control children. Furosemide in plasma was analyzed by spectrofluorometry. After a single intravenous dose of furosemide (1 mg/kg body wt.) the nephrotic children showed lower initial plasma concentrations because of the larger volume of distribution. The mean half-life of furosemide in nephrotic children (38.5 +/- 7.8 min) was significantly longer than in the control group (28.0 +/- 7.7 min). The two groups did not differ in the body clearance of total furosemide. The average serum clearance was 4.95 +/- 1.7 ml/min/kg body wt. in the control group and 5.10 +/- 1.4 ml/min/kg body wt. in the nephrotic children. There was a significant reduction in urine sodium and distribution volume, whereas potassium excretion remained unchanged.