LC-MS method for determination and pharmacokinetic study of chimaphilin in rat plasma after oral administration of the traditional Chinese medicinal preparation Lu xian cao decoction

Lu xian cao (Hebra pyrolae) is a traditional Chinese medicine used for the treatment of several major diseases. Chimaphilin has been demonstrated one of the major active components in Lu xian cao by modern pharmacological studies. In this study, a liquid chromatography-mass spectrometry method for the determination of chimaphilin in rat plasma was developed and validated. The separation was carried out on a C18 column using methanol and water as mobile phase after the plasma sample was extracted with diethyl ether. Atmospheric pressure chemical ionization in negative ion mode and selected ion monitoring method were developed to determine [M]- at 186 and 210 for chimaphilin and benzil (internal standard), respectively. The lower limit of quantitation was 10 ng/ml and the calibration curve was linear (r>0.9964) over the concentration range 10-1000 ng/ml. The method was demonstrated reproducible and reliable with intra-day precision<11.5%, inter-day precision<7.6%, accuracy in the range of 88.4-113.0%, and mean extraction recovery excess of 83.0%, which were all calculated from the quality control samples at concentrations of 20, 100, and 500 ng/ml. The method was successfully applied to pharmacokinetic study of chimaphilin in rat plasma following oral administration of a 30-mg/kg dose of chimaphilin in Lu xian cao decoction to male Wistar rats.