ABSTRACT
OBJECTIVE: To study the enzymatic kinetics of TM-2 in rat, Beagle dog and human liver microsomes by LC-MS/MS. METHODS: TM-2 was incubated with liver microsomal incubation system. LC-MS/MS method was established for quantitative analysis of TM-2 with cabazitaxel as internal standard. The enzyme kinetics parameters Vmax and Km was calculated by the GraphPad Prism 5.0 software. RESULTS: A rapid and sensitive LC-MS/MS method was developed to study the enzyme kinetics of TM-2 in rat, Beagle dog and human liver microsome. The corresponding enzymatic kinetic parameters in rat, Beagle dog and human were as follows: Vmax values were 16.3, 354.6 and 154.8 nmol•min-1•mg(protein)-1, respectively; Km values were 25.7, 313.8 and 89.4 μmol• L-1, respectively; CLint values were 0.63, 1.13 and 1.73 mL•min-1•mg(protein)-1, respectively. CONCLUSION: The result indicates that there are species differences in the activity of metabolic enzyme and the affinity of TM-2 to the metabolic enzyme. Enzyme kinetic parameters obtained of TM-2 provide important parameters for the further study.