有限采样法评价肝脏CYP3A代谢活性的实验研究

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(Cls)为指标,评价有限采样法(LSS)预测肝脏CYP3A抑制状态下代谢活性的可行性。方法:采用系列剂量的CYP3A选择性抑制剂酮康唑预处理大鼠,静脉注射MDZ后在若干时间点收集血浆样品并检测MDZ浓度,经逐步回归分析和Jack-knife验证建立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:由两点(60、90min)或三点(30、60、90min或30、60、120min)血浆药物浓度建立的LSS预测模型所得到的Cls估计值(Clest)与实际计算值(Clobs)之间具有良好的相关性,误差小,特别是两点LSS模型则更为简便。结论:本研究结果表明,以MDZCls为指标,采用LSS评价大鼠肝脏CYP3A抑制状态下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治疗药物的给药方案提供了理论依据和实验室证据。

Experimental study on limited sampling strategy to predict metabolizing activity of hepatic CYP3A

AIM:To evaluate feasibility of a limited sampling strategy(LSS)in the prediction of inhibited hepatic CYP3A activity with systemic clearance of midazolam(MDZ),a phenotyping probe drug for hepatic CYP3A activity.METHODS:Linear regression analysis and a Jack-knife validation procedures were performed in one group of rats pretreated with a serial doses of ketoconazole,a selective inhibitor on CYP3A,as training set to establish the most informative LSS model for accurately estimating the clearance of MDZ.Another group of rats in same setting were used as validation set to estimate the individual clearance(Clest)based on predictive equations derived from the training set.RESULTS:LSS models derived from two or three sampling time points,including 60 and 90 min,30,60 and 90 min and 30,60 and 120 min,exhibited best correlation and acceptable errors between Clobs and Clest were chosen to evaluate to hepatic CYP3A activity.CONCLUSION:The results indicated that limited plasma sampling for predicting systemic clearance of MDZ is a less complicated method to evaluation of CYP3A phenotyping when the activity of hepatic CYP3A was inhibited.The present study provided theoretical basis and laboratory evidence for LSS to clinically evaluate metabolizing function of liver and design rational drug regimen.