RT Journal Article
SR Electronic
T1 Identification of Rat Urinary and Biliary Metabolites of Esonarimod, a Novel Antirheumatic Drug, Using Liquid Chromatography/Electrospray Ionization Tandem Mass Spectrometry with Postcolumn Addition of 2-(2-Methoxyethoxy)Ethanol, a Signal-Enhancing Modifier
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 806
OP 812
VO 29
IS 6
A1 Jun-Ichi Yamaguchi
A1 Mari Ohmichi
A1 Masatoshi Hasegawa
A1 Hideo Yoshida
A1 Naoyoshi Ogawa
A1 Shohei Higuchi
YR 2001
UL http://dmd.aspetjournals.org/content/29/6/806.abstract
AB The biotransformation of esonarimod (KE-298) [(±)-2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid], a new antirheumatic drug, was investigated in rats. Urinary and biliary excretions within 24 h after oral administration of 5 mg/kg [14C]esonarimod accounted for 89 and 10% of the dose, respectively. Initial metabolite analysis by liquid chromatography/electrospray ionization tandem mass spectrometry with negative ion mode, in which a mobile phase of 20 mM ammonium acetate (pH 4.6)/methanol with gradient-elution mode was used, failed to obtain any structural information on most of the metabolites due to poor sensitivity. To overcome this problem, postcolumn addition of 2-(2-methoxyethoxy)ethanol, a powerful signal-enhancing modifier, to the mobile phase was used, allowing pronounced signal enhancement and structural elucidation of urinary and biliary metabolites. The results of metabolite analysis suggested that esonarimod is predominantly biotransformed to a pharmacologically active metabolite, thiol-containing deacetyl-esonarimod (M-I), and subsequently undergoes extensive metabolism, mainlyS-methylation followed by the combination ofS-oxidation and oxidative conversion of the aromatic methyl group. No disulfide metabolites, such as M-I-cysteine mixed disulfide and M-I-dimer, were found in the excreta. This finding is probably evidence supporting the notion that the reactivity of the thiol moiety of M-I with macromolecules in vivo is extremely lower than that of common thiol-containing drugs. The American Society for Pharmacology and Experimental Therapeutics