Analysis of mesocarb analogues in urine and plasma of rats by high-performance liquid chromatography and thermospray liquid chromatography-mass spectrometry.

The pharmacokinetics and metabolism of synthetic 2-hydroxymesocarb and 4-methyl-2-hydroxymesocarb analyzed by HPLC-DAD and thermospray LC-MS were studied in rats. Multistep liquid-liquid extraction (LLE) was used with diethyl ether at pH 7.0. The major metabolites of 2-hydroxymesocarb in both urine and plasma of the rat were the p-hydroxylated derivative of the phenylcarbamoyl group of the parent drug. The metabolites of 4-methyl-2-hydroxymesocarb in urine of rats may be the oxidized forms at the phenylcarbamoyl group of the parent drug. Absorption (ka) and elimination (ke) rate constants in plasma of 2-hydroxy-mesocarb were 0.0300 and 0.00485 min-1, respectively; those of 4-methyl-2-hydroxymesocarb were 0.0546 and 0.00797 min-1, respectively. The half-lives (t1/2) of 2-hydroxymesocarb and 4-methyl-2-hydroxymesocarb in plasma were 144 and 86 min, respectively.