Abstract: Objective To study the plasma concentration and pharmacokinetics of 3,29-Dibenzoyl Karounitriol (3,29-DK) from sustained- release pellets and extracts of Trichosanthes at different time points in rats using high-performance liquid chromatography- tandem mass spectrometry (LC-MS/MS). Methods Healthy male SD rats were given a single gavage of Trichosanthes sustained-release pellets or Trichosanthes extract, and orbital blood samples were taken at different time points within 48 h after drug administration in the pellet group and within 5 h in Trichosanthes extract group for determination of the plasma concentrations of 3,29-DK using LC-MS/MS. The standard curve of 3,29-DK content was established, and the specificity, minimum detection limit, precision and accuracy, extraction recovery, stability and matrix effect of LC-MS/MS analysis were assessed. The mean plasms levels of 3,29-DK at different time points after the drug administration were determined and its pharmacokinetic parameters were calculated using Das 2.0 software. Results LC-MS/MS analysis showed a good linearity of 3,29-DK concentration within the range of 0.5-32 ng/mL, and the results of methodological validation confirmed the validity of this method for biological sample determination. Trichosanthes sustained-release pellets and Trichosanthes extract showed significant differences in their AUC(0- t), AUC(0- ∞), MRT(0- t), MRT(0- ∞), t1/2z and Tmax of 3,29-DK after administration in rats (P<0.05). Conclusion Trichosanthes sustained-release pellets are capable of sustained-release of 3,29-DK in rats, and thus provides a basis for the study of new dosage forms of Trichosanthes.

Key words: high-performance liquid chromatography-tandem mass spectrometry, Trichosanthes sustained-release pellets, 3,29- dibenzoyl karounitriol, pharmacokinetics