TY - JOUR T1 - AMIDE <em>N</em>-GLUCURONIDATION OF MAXIPOST CATALYZED BY UDP-GLUCURONOSYLTRANSFERASE 2B7 IN HUMANS JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 545 LP - 551 DO - 10.1124/dmd.32.5.545 VL - 32 IS - 5 AU - Donglu Zhang AU - Weiping Zhao AU - Vikram A. Roongta AU - James G. Mitroka AU - Lewis J. Klunk AU - Mingshe Zhu Y1 - 2004/05/01 UR - http://dmd.aspetjournals.org/content/32/5/545.abstract N2 - MaxiPost [(3S)-(+)-(5-chloro-2-methoxyphenyl)-1,3-dihydro-3-fluoro-6-(trifluoromethyl)-2H-indole-2-one), or BMS-204352)] is a potent and specific maxi-K channel opener for potential use to treat stroke. This article describes structural characterization of a major human N-glucuronide metabolite of BMS-204352 and identification of the enzyme responsible for the N-glucuronidation reaction. After intravenous administrations of [14C]BMS-204352 (10 mg, 50 μCi) to eight healthy human subjects, one major metabolite M representing an average of 17% of the radioactive dose was excreted in pooled urine collected over 0 to 336 h after dosing. A major biliary metabolite of dogs dosed with [14C]BMS-204352 (5 mg/kg), which represented about 33% of the dose, has the same retention time and the same tandem mass spectrometry fragmentation pattern as the human urinary metabolite M. Four hundred fifty micrograms of the metabolite was isolated from the dog bile and analyzed by NMR. Long-range 1H-13C NMR experimentation indicated that the glucuronic acid moiety was at the nitrogen site. The N-glucuronide of BMS-204352 was stable up to 24 h at 37°C in the incubations at different pH values (3.0, 7.4, and 9.0) and with glucuronidases from Escherichia coli and Helix pomatia. Of the seven human UDP-glucuronosyltransferases (UGT) isozymes (1A1, 1A3, 1A4, 1A6, 1A7, 1A10, and 2B7) tested, only UGT2B7 produced metabolite M. UGT2B7-catalyzed N-glucuronidation of BMS-204352 exhibited Michaelis-Menten kinetics with a Km of 14.2 μM and Vmax of 0.29 nmol/min · mg of protein. Collectively, these results suggest that amide N-glucuronidation, a major elimination pathway of MaxiPost, is catalyzed by UGT2B7 in humans. This N-glucuronide represents a fully characterized amide N-glucuronide, and glucuronidation at the nitrogen represents a newly identified conjugation reaction for UGT2B7. The American Society for Pharmacology and Experimental Therapeutics ER -