The urinary excretion of frusemide and its metabolites by kidney transplant patients.

Urine from 5 renal transplant recipients treated with frusemide was analyzed for unchanged frusemide (F), glucuronidated frusemide (G) and 4-chloro-5-sulfamoylanthranilic acid (CSA) by HPLC. In 3 recipients, whose renal function recovered steadily and whose hepatic function was normal throughout, the ratio of frusemide to its metabolites, F/(F + G + CSA), increased steadily in conjunction with the recovery of renal function. In one patient, who received frusemide 200-400 mg/day i.v., the urinary CSA concentration was 64-102 micrograms X ml-1. In 2 patients who experienced shock and/or hepatic dysfunction after transplantation, the F/(F + G + CSA) ratio fluctuated.