QUANTITATION OF CARVEDILOL OXIDATIVE METABOLITES IN HUMAN PLASMA USING LIQUID CHROMATOGRAPHY TANDEM MASS SPECTROMETRY

A sensitive and efficient method was developed for the determination of carvedilol and its metabolite in human plasma by LC-MS/MS. Plasma samples were hydrolysed with beta-glucuronidase and the target compounds were extracted with liquid liquid extraction using diethyl ether in dichloro methane as solvent. The extracts were completely derivatized and analysed by LC-MS/MS. The linearity of the assay ranges from 0.250 ng/mL to 200.0 ng/mL for carvedilol and from 0.500 ng/mL to 30.0 ng/mL for 4-hydroxy carvedilol. The absolute recovery of carvedilol and its metabolite added to blank plasma sample was 70.28 82.90%. The reproducibility was from 0.96 to 8.28 for the intraday assay and from 1.65 to 6.09 for the interday assay precision. Repetitive thawing and freezing did not have an affect on metabolite through a minimum of three cycles. Thawed samples remaining in plasma for 4h before extraction were with 5% of theoretical value. Stability of the extracted samples on the auto sampler at room temperature was evaluated for 34 h and was observed to with in 12% of a fresh analytical sample for 4 hydroxy carvedilol. The proposed LC-MS/MS method was effective for the determination of carvedilol and it metabolite in human plasma.