19F-NMR and directly coupled HPLC-NMR-MS investigations into the metabolism of 2-bromo-4- trifluoromethylaniline in rat: a urinary excretion balance study without the use of radiolabelling

Abstract

1. The metabolic fate and urinary excretion of 2-bromo-4-trifluoromethylaniline has been studied in rat using ¹⁹F-NMR spectroscopic and directly coupled HPLC-NMRMS methods. The compound was dosed to Sprague-Dawley rats (50 mg kg⁻, i.p.) and urine collected over 0-8, 8-24 and 24-48 h post-dosing. 2. A total urinary recovery of 53.5 ± 7.0% of the dose was achieved up to 48 h after dosing. The major metabolite in the urine was identified as 2-amino-3-bromo-5-trifluoromethylphenylsulphate accounting for a total of 35.7 ± 6.2% of the dose. 3. Further metabolites detected were 2-bromo-4-trifluoromethylphenylhydroxylamine-N-glucuronide (9.7 ± 0.2% of the dose), 2-bromo-4-trifluoromethylaniline-N-glucuronide (3.0 ± 0.3%) and 2-amino-3-bromo-5-trifluoromethylphenylglucuronide (2.8 ± 0.4). Minor metabolites, including 2-bromo-4-trifluoromethylphenylhydroxylamine-O-glucuronide, 2-amino-3-bromo-5-trifluoromethylphenol and 2-bromo-4- trifluoromethylphenylsulphamate, in total accounted for 2.3 ± 0.9% of the dose. 4. Directly coupled HPLC-NMR-MS and ¹⁹F-NMR spectroscopy proved to be efficient techniques for the unequivocal and rapid determination of the urinary metabolic fate and excretion balance of fluorinated xenobiotics without the need for radiolabelling.