OBJECTIVE To develop a sensitive and specific LC/MS/MS
method for the direct determination of
flunarizine in human plasma.METHODS Flunarizine and internal standard diphenhydramine were extracted from 0.25 mL plasma using liquid-liquid extraction,then separated on a Zorbax SB C_(18) column.The mobile phase consisted of acetonitrile-water-formic acid(80∶20∶0.5).A Finnigan TSQ
tandem mass spectrometer equipped with atmospheric pressure chemical ionization source was used as detector and was operated in the positive ion mode.Selected reaction monitoring(SRM)
mode using the precursor to product the ion of m/z 405 to m/z 203 and m/z 256 to m/z 167 was performed to quantify flunarizine and the internal standard,respectively.RESULTS The linear calibration curves were obtained in the concentration range of 0.2～200.0 μg·L~(-1).The lower limit of quantification was 0.2 μg·L~(-1).The inter-and intra-day precision (RSD) were below 6.5%,and the accuracy(RE) was within 99.1% calculated from QC samples.The method gave the mean recovery of 75.1% and 73.1% to flunarizine and internal standard diphenhydramine,respectively.The total chromatographic run time was only 3.1 min.CONCLUSION The method is proved to be special,sensitive,and suitable for the clinical investigation of flunarizine pharmacokinetics.
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