Objectives: Riptolide (TPL) has been shown to have a good clinical effect on rheumatoid
arthritis (RA). We designed TPL microspheres (TPL-MS) and investigated its metabolic behavior
in human, dog, rabbit and rat liver microsomes (HLM, DLM, RLM and SDRLM) with UPLC-
Methods: First, a UPLC-MS/MS method was established to measure the concentration of TPL in
samples. The sample was separated on a C18 column (2.1×100 mm, 1.8μm) and eluted with a gradient
elution. The precursor ions/product ions were m/z 378.1/361.0 for TPL and 260.0/116.2 for the
internal standard. Then T1/2, Vmax and CLint were calculated from the above data. Finally, the metabolites
of TPL-MS were identified by high-resolution UPLC-MS/MS. The sample was separated on a
C18 column (2.1×100 mm, 2.2 μm) and eluted with isocratic elution. Mass spectrometric detection
was carried out on a thermo Q-exactive mass spectrometer with HESI. The scanning range of precursor
ions was from m/z 50 to m/z 750.
Results: Through several indicators including standard curve, precision, accuracy, stability, matrix
effect and recovery rate, the enzymatic kinetics parameters including T1/2, Vmax and CLint were evaluated.
Several metabolites of TPL-MS were identified.
Discussion: UPLC-MS/MS method is an accurate and sensitive method for the determination of
TPL in liver microsome samples with good precision, accuracy and stability. The variation of parameters
indicated that the microspheres can delay the elimination of TPL in liver microsomes.
Conclusion: The metabolism of TPL-MS varied among species, but no new metabolites appeared.