In vitro-in vivo extrapolation of CYP2C8-catalyzed paclitaxel 6α-hydroxylation: effects of albumin on in vitro kinetic parameters and assessment of interindividual variability in predicted clearance
In vitro-in vivo extrapolation of CYP2C8-catalyzed paclitaxel 6α-hydroxylation: effects of albumin on in vitro kinetic parameters and assessment of interindividual variability in predicted clearance
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DOI：
10.1007/s00228-011-1001-z
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发表时间：
2011-08-01
影响因子：
2.9
通讯作者：
Miners, John O.
中科院分区：
文献类型：
--
作者：
Wattanachai, Nitsupa;Polasek, Thomas M.;Miners, John O.
目的研究牛血清白蛋白（BSA）对紫杉醇6 α-羟基化代谢动力学的影响，确定加入BSA是否能改善紫杉醇6 α-羟基化代谢动力学预测;方法采用人肝微粒体（HLM）对紫杉醇6 α-羟基化反应的动力学研究和重组CYP 2C 8在有和无BSA（2% w/v）补充的孵育中进行表征，并外推体外动力学数据以提供体内清除率的估计值。结果补充HLM与BSA孵育导致微粒体紫杉醇6a-羟基化的固有清除率增加3.6倍，主要是由于K-m降低（7.08 +/- 2.50至2.26 +/- 0.39 μ M），而向重组CYP 2C 8孵育液中加入BSA导致固有清除率约加倍。当在存在BSA的情况下获得的体外数据用于IV-IVE时，预测的体内肝脏清除率的平均值与临床数据一致。Simcyp预测20至30倍的个体间变异性在体内紫杉醇肝清除率通过6 α-hydroxylation pathway.Conclusions人肝微粒体Km和固有清除率值是过度和低估，分别进行孵育时的CYP 2C 8底物紫杉醇没有BSA补充。基于BSA存在下生成的动力学参数的IV-IVE提高了预测紫杉醇肝清除率的准确性。
Objectives This study aimed to characterize the effects of bovine serum albumin (BSA) on the kinetics of CYP2C8-catalyzed paclitaxel 6 alpha-hydroxylation in vitro; determine whether the addition of BSA to incubations improves the prediction of paclitaxel hepatic clearance via this pathway in vivo; and assess interindividual variability in predicted clearance.Methods The kinetics of paclitaxel 6 alpha-hydroxlation by human liver microsomes (HLM) and recombinant CYP2C8 were characterized in incubations performed with and without BSA (2% w/v) supplementation, and the in vitro kinetic data were extrapolated to provide estimates of in vivo clearances. The Simcyp population-based ADME simulator was used to determine interindividual variability in the predicted clearances.Results Supplementation of incubations of HLM with BSA resulted in a 3.6-fold increase in the microsomal intrinsic clearance for paclitaxel 6a-hydroxylation, due mainly to a reduction in K-m (7.08 +/- 2.50 to 2.26 +/- 0.39 mu M), while addition of BSA to incubations of recombinant CYP2C8 resulted in an approximate doubling of intrinsic clearance. Mean values of predicted in vivo hepatic clearance were in good agreement with clinical data when in vitro data obtained in the presence of BSA were used for IV-IVE. Simcyp predicted 20- to 30-fold interindividual variability in in vivo paclitaxel hepatic clearance via the 6 alpha-hydroxylation pathway.Conclusions Human liver microsomal K-m and intrinsic clearance values are over-and underpredicted, respectively, when incubations of the CYP2C8 substrate paclitaxel are performed without BSA supplementation. IV-IVE based on kinetic parameters generated in the presence of BSA improves the accuracy of predicted paclitaxel hepatic clearance.