Simultaneous determination of metoprolol and its metabolites, α-hydroxymetoprolol and O-desmethylmetoprolol, in human plasma by liquid chromatography with tandem mass spectrometry: Application to the pharmacokinetics of metoprolol associated with CYP2D6 genotypes.

Abstract

A rapid and simple LC with MS/MS method for the simultaneous determination of

metoprolol and its two CYP2D6-derived metabolites, alpha-hydroxy- and

O-desmethylmetoprolol, in human plasma was established. Metoprolol (MET), its two

metabolites, and the internal standard chlorpropamide were extracted from plasma

(50 muL) using ethyl acetate. Chromatographic separation was performed on a Luna

CN column with an isocratic mobile phase consisting of distilled water and

methanol containing 0.1% formic acid (60:40, v/v) at a flow rate of 0.3 mL/min.

The total run time was 3.0 min per sample. Mass spectrometric detection was

conducted by ESI in positive ion selected-reaction monitoring mode. The linear

ranges of concentration for MET, alpha-hydroxymetoprolol, and

O-desmethylmetoprolol were 2-1000, 2-500, and 2-500 ng/mL, respectively, with a

lower limit of quantification of 2 ng/mL for all analytes. The coefficient of

variation for the assay's precision was </= 13.2%, and the accuracy was

89.1-110%. All analytes were stable under various storage and handling conditions

and no relevant cross-talk and matrix effect were observed. Finally, this method

was successfully applied to assess the influence of CYP2D6 genotypes on the

pharmacokinetics of MET after oral administration of 100 mg to healthy Korean

volunteers.