title: Simultaneous determination of furosemide and two of its possible metabolites in biological fluids.
abstract: By the means of thin-layer chromatography (TLC) prior to fluorometry it was possible to determine furosemide (F) in plasma and urine with improved specificity. Antranilic acid (A) and 4-chlor-5-sulphamoyl-antranilic acid (CSA) could be determined simultaneously with F in plasma. In urine, only F and A could be determined quantitatively by this method. The sensitivity is 0.1 microgram/ml for F and 0.15-0.20 microgram/ml for A and CSA. By means of TLC prior to fluorometry the blank value for F was reduced in normal subjects and in different groups of patients, and its diurnal variation was eliminated. The average values of the plasma concentrations of F after the intravenous injection of 40 mg into 12 normal subjects were at all times found to be lower by the TLC method than by the fluorometric method without TLC. A higher plasma clearance and a lower volume of distribution were found for F when the values obtained by the TLC method were used for the calculation.
mesh_terms: D002855:Chromatography, Thin Layer; D005665:Furosemide / Q000031:analogs & derivatives* / Q000032:analysis* / Q000097:blood / Q000652:urine; D006207:Half-Life; D006801:Humans; D013050:Spectrometry, Fluorescence
chemical_list: D005665:Furosemide