Background: 2-Cyclopentanecarbonyl-1,2,3,6,7,11b-hexahydro-pyrazino[2,1- a]isoquinolin-
4-one (P96), was found to be a novel drug candidate with one chiral center to treat schistosomiasis
caused by Schistosoma japonicum.
Objective: To study pharmacokinetic characteristics, a simple, rapid and sensitive liquid chromatography-
tandem mass spectrometry (LC-MS/MS) method was developed and fully validated for the quantification
analysis of P96 in rat plasma.
Methods: Chromatographic separation was performed on a C18 column with gradient eluted mobile
phase composed of acetonitrile and water at a flow rate of 0.5 mL/min. Detection was performed on a
triple-quadrupole tandem mass spectrometer using positive mode electrospray ionization in the multiple
reactions monitoring (MRM) mode.
Results: Excellent linearity was observed in the range of 3-900 ng/mL with the lower limit of quantification
of 3 ng/mL in rat plasma for P96. The intra- and inter-day precisions exhibited less than 6.6%.
Mean recoveries ranged from 96.9% to 102.4%. This method was applied to investigate the enantioselective
differences on the pharmacokinetics between (R,S)-P96 and its enantiomers in rats after oral
administration. The enantioselective differences of (R)-P96, (S)-P96 and (R,S)-P96 were found and
Conclusion: The established method was found to be accurate, precise, and sensitive and can be applied
to investigate the stereoselective differences on pharmacokinetics between rac-P96 and its enantiomers.