噻吩诺啡在人、比格犬和大鼠肝微粒体中体外代谢比较

采用体外肝微粒体孵育体系, 研究噻吩诺啡在大鼠、比格犬和人肝微粒体中酶代谢动力学及代谢产物差异。通过对噻吩诺啡浓度、微粒体蛋白含量和孵育时间等条件的考察优化噻吩诺啡与肝微粒体的反应体系; 应用LC-MS/MS定量检测孵育体系中的噻吩诺啡及代谢产物, 分析比较噻吩诺啡在3种肝微粒体中代谢产物种类和生成量的差异, 计算并比较相应的动力学参数。噻吩诺啡在人肝微粒体中代谢转化最慢, 其相应的动力学参数K_m = (4.00 ± 0.59) µmol·L⁻¹、V_max = (0.21 ± 0.06) µmol·L⁻¹·min⁻¹、T_1/2 = (223 ± 6.10) min、CL_int = (117 ± 3.19) mL·min⁻¹·kg⁻¹; 比格犬和大鼠肝微粒体中相应的参数K_m、V_max、T_1/2和CL_int分别为 (3.57 ± 0.69) 和 (3.28 ± 0.50) µmol·L⁻¹、(0.18 ± 0.04) 和 (0.14 ± 0.04) µmol·L⁻¹·min⁻¹、(244 ± 1.21) 和 (70.7 ± 1.05) min、(213 ± 1.06) 和    (527 ± 7.79) mL·min⁻¹·kg⁻¹。在3个种属肝微粒体中均观察到噻吩诺啡的6个I相代谢产物, 但6个产物的相对生成百分比在不同种属肝微粒体中有一定差异。实验结果表明, 噻吩诺啡在体外人、比格犬和大鼠肝微粒体中主要的I相代谢途径相同, 但是代谢产物的生成量及噻吩诺啡的代谢动力学性质存在着一定的差异。

In vitro comparison of thienorphine metabolism in liver microsomes of human,Beagle dog and rat

The inter-species differences of thienorphine metabolism were investigated in human, Beagle  dog and rat liver microsomes, by comparing enzyme kinetics of the parent drug and the formation of its major metabolites.  The incubation systems of thienorphine with liver microsomes of the three species were optimized in terms of thienorphine concentration, microsomal protein content and incubation time.  The concentrations of thienorphine and its metabolites in incubates were measured by a LC-MS/MS method.  The biotransformation of thienorphine by human liver microsomes was the lowest among the three species.  The K_m, V_max, CL_int and T_1/2 of thienorphine obtained from human liver microsomes were (4.00 ± 0.59) µmol·L⁻¹, (0.21 ± 0.06) µmol·L⁻¹·min⁻¹, (117 ± 3.19) mL·min⁻¹·kg⁻¹ and (223 ± 6.10) min, respectively.  The corresponding kinetic  parameters for dog and rat liver microsomes were (3.57 ± 0.69) and (3.28 ± 0.50) µmol·L⁻¹, (0.18 ± 0.04) and (0.14 ± 0.04) µmol·L⁻¹·min⁻¹, (213 ± 1.06) and (527 ± 7.79) mL·min⁻¹·kg⁻¹, (244 ± 1.21) and (70.7 ± 1.05) min, respectively.  A total of six phase I metabolites were observed in liver microsomes, including one N-dealkylated metabolite, three oxidative metabolites and two N-dealkylated oxidation metabolites.  All these six metabolites were detected in the liver microsomes of the three species.  However, the relative amounts of the metabolites generated were different in three species.  The results indicated that the major phase I metabolic pathway of thienorphine was similar in the liver microsomes from all three species.  However, the inter-species differences observed were relative amounts of the metabolites as well as the metabolic characteristics of thienorphine in liver microsomal incubates.