Enantioselective determination of propafenone and its metabolites in humanplasma by liquid chromatography mass spectrometry

A sensitive and stereospecific method was developed to determine propafenon e (PPF), 5-hydroxypropafenone (5-OHP) as well as their glucuronide and sulf ate conjugates in human plasma. Quantitative analyses and preparative isola tions of PPF and 5-OHP were performed on a Nucleosil C-18 column after liqu id-liquid extraction. Afterwards the enantiomeric ratios of PPF and 5-OHP w ere determined on a Chiral-AGP column with ion trap mass spectrometric dete ction in the selected reaction monitoring (SRM) mode via electrospray ioniz ation (ESI). The enantiomers of PPF and 5-OHP were separated with different mobile phases. For PPF enantiomers, the mobile phase consisted of 10 mM am monium acetate buffer (pH 5.96)-1-propanol (100:9, v/v), at a how-rate of 0 .5 ml/min; And for 5-OHP enantiomers, the mobile phase was 10 mM ammonium a cetate buffer (pH 4.1)-2-propanol (100:0.9, v/v), at a flow-rate of 0.6 ml/ min. The SRM transitions m/z 342 to m/z 324 and m/z 358 to m/z 340 were mon itored for detection of enantiomers of PPF and 5-OHP, respectively. Linear calibration curves were obtained in the concentration range of 20-1600 ng/m l for each enantiomer of PPF and 20-500 ng/ml for the 5-OHP enantiomer. The limits of quantification for each enantiomer of PPF and 5-OHP were found t o be 20 ng/ml. Precision and accuracy were within 11% over the calibration range for each of the analytes. Incubation of the plasma samples with beta- glucuronidase/arylsulfatase and the use of the specific beta-glucuronidase inhibitor saccharo-1,4-lactone allows the quantitation of both the glucuron ide and sulfate conjugates of the enantiomers. The method was applied to hu man plasma samples from ten Chinese male volunteers after oral administrati on of 300 mg racemic propafenone. (C) 1999 Elsevier Science B.V. All rights reserved.