OBJECTIVE To establish a rapid,simple,precise and sensitive ultra performance liquid chromatography(UPLC) method for determination of paeoniflorin-6'-O-benzene sulfonate(acylated derivative of Pae,CP-25) and its primary metabolite(Pae,M1) in rat plasma,and to investigate the effects of gender,food and disease status on the pharmacokinetics after oral administration in rats.METHODS Plasma samples and calibrators were extracted with methanol after addition of the internal standard solution.After evaporation of the methanol layer,the residue was reconstituted in mobile phase,and a 2 μL of the sample was injected into a Waters ACQUITY UPLC BEH C18(2.1 mm × 50 mm,1.7 μm) column for separation at a flow rate of 0.5 mL·min^(-1) at 40℃.The mobile phase was composed of 0.1% formic acid in water and methanol(68∶32,V/V).RESULTS The developed UPLC-MS/MS method was linear in the concentration range of 2-800 mg·L^(-1).Validation of the method proved that the method′s precision,selectivity and stability were all within the acceptable limits.Pharmacokinetics study showed that CP-25 could have more extensive distribution in females than that in males but no differences in M1.Food intake could also increase the extent of absorption and decrease the rate of clearance of CP-25 and M1 after oral administration in rats.The disease status would decrease the absorption of CP-25 in rats.Comparing single-and multiple-dosing in adjuvant arthritis(AA) model,absorption of CP-25 and M1 was improved with increasing dosage.CONCLUSION The developed UPLC-MS/MS method is sensitive,specific and was successfully applied to the pharmacokinetics of CP-25 and M1 in rats.And a significant gender,food intake and disease status differences for CP-25 and M1 were observed in this study.
