探针药物咪哒唑仑有限采样法预测肝损伤大鼠 CYP 3A 代谢活性的研究

 目的 以细胞色素 P450 （ CYP ） 3A 探针药物咪哒唑仑（ MDZ ）的系统清除率（ CL _s ）为指标，评价有限采样法（ LSS ）预测肝脏损伤状态下 CYP 3A 代谢活性的可行性。 方法 采用系列浓度的 四氯化碳溶液 预处理大鼠， 24 h 后，静脉注射 MDZ ，在若干时间点采血检测血浆 MDZ 浓度。留取血清并检测 丙氨酸氨基转移酶（ ALT ）和天冬氨酸氨基转移酶（ AST ）活性 。经逐步回归分析和 Jack-knife 方法 验证，建立最终的 LSS 模型。对经相同处理的另一随机群体进行验证分析，评价该 LSS 模型方程的准确性和重现性。 结果 系列浓度四氯化碳溶液造成肝脏不同程度损伤。由单点（ 45 min ）或两点（ 5 ， 4 5 min ）血浆药物浓度建立的 LSS 预测模型所得到的 CL _s 估计值（ CL _est ）与实际计算值（ CL _obs ）之间具有良好的相关性，误差小。两点 LSS 模型对样本预测的相关性较单点 LSS 更优（ r =0.96 ），而单点 LSS 模型则更显简便。 结论 本实验表明，以 MDZ 清除率为指标，采用 45 min 或 5. 4 5 min 的 有限采样方案评价肝脏损伤状态下 CYP 3A 的代谢活性是一种准确而简便的方法，为今后推广到临床评价肝脏代谢功能从而制定和调整给药方案提供了理论依据和实验室证据。

Study on a Limited Sampling Strategy to Predict the Metabolic Activity of Hepatic CYP 3A with Phenotyping Probe Midazolam in Rats Developing Liver Injury Induced by Carbon Tetrachloride

OBJECTIVE To evaluate the feasibility of a limited sampling strategy (LSS) for the prediction of damaged hepatic CYP3A activity by the systemic clearance of midazolam (MDZ), a CYP3A phenotyping probe. METHODS Rats pretreated with or without serial concentrations of carbon tetrachloride （CCl4） solutions were used as training set. After 24 h, the activities of serum ALT and AST were detected. Linear regression analysis and a Jack-knife validation procedure was performed based on plasma MDZ concentrations at specific times after sublingual vein injection of MDZ to establish the most informative LSS equations for accurately estimating the clearance of MDZ. Another rats in the same setting was used as the validation set to confirm the individual values of estimated clearance （CLest） that were derived from the predictive equations developed in the training set. RESULTS Series of CCl4 solutions induced different degree of liver injury. LSS models derived from single or two sampling time points, at 45 min and 5.45 min, exhibited a good accuracy and acceptable error for estimating the CLobs of MDZ to evaluate hepatic CYP3A activity, especially the 5.45 min LSS model showed more accurate. CONCLUSION The results support the hypothesis that limited sampling strategy is less complicated than the usual method for estimating hepatic CYP3A phenotyping by predicting the systemic clearance of MDZ clearance when liver is damaged in rats. The present study provided theoretical basis and laboratory evidence for LSS to clinically evaluate metabolizing function of liver and design rational drug regimen.