Paris S, Blaschke G, Locher M, Borbe H O, Engel J
Institute of Pharmaceutical Chemistry, University of Münster, Germany.
J Chromatogr B Biomed Sci Appl. 1997 Apr 11;691(2):463-71. doi: 10.1016/s0378-4347(96)00480-x.
An achiral HPLC method using a silica gel column as well as two independent chiral analytical methods by HPLC and capillary zone electrophoresis (CZE) were developed in order to investigate the in vitro metabolism of the racemic antiasthmatic/antiallergic drug flezelastine. The chiral HPLC analysis was performed on a Chiralpak AD column, which also allowed the simultaneous separation of the N-dephenethyl metabolite. The chiral separation by CZE was achieved by the addition of beta-cyclodextrin to the run buffer. The stereoselectivity of the in vitro biotransformation of flezelastine was investigated using liver homogenates of different species. Depending on the species, diverse stereoselective aspects were demonstrated. The determination of the enantiomeric ratios of flezelastine and of N-dephenethylflezelastine after incubations of racemic flezelastine with liver microsomes revealed that porcine liver microsomes showed the greatest enantioselectivity of the biotransformation. (-)-Flezelastine was preferentially metabolized. After incubations with bovine liver microsomes the enantiomer of N-dephenethylflezelastine formed from (+)-flezelastine dominated. Incubations of the pure enantiomers of flezelastine with induced rat liver microsomes resulted in the stereoselective formation of a hitherto unknown metabolite, which was only detected in samples of (+)-flezelastine. Initial structure elucidation of the compound indicated that the new metabolite was most likely an aromatically hydroxylated derivative of the N-dephenethylflezelastine.
为了研究消旋抗哮喘/抗过敏药物非索非那定的体外代谢情况，开发了一种使用硅胶柱的非手性高效液相色谱（HPLC）方法以及两种独立的手性分析方法，即HPLC法和毛细管区带电泳（CZE）法。手性HPLC分析在Chiralpak AD柱上进行，该柱还能同时分离N-去苯乙胺代谢物。通过在运行缓冲液中添加β-环糊精实现了CZE的手性分离。使用不同物种的肝脏匀浆研究了非索非那定体外生物转化的立体选择性。根据物种不同，表现出了不同的立体选择性方面。用消旋非索非那定与肝微粒体孵育后，测定非索非那定和N-去苯乙胺非索非那定的对映体比例，结果表明猪肝微粒体的生物转化表现出最大的立体选择性。(-)-非索非那定优先被代谢。用牛肝微粒体孵育后，由(+)-非索非那定形成的N-去苯乙胺非索非那定对映体占主导。将非索非那定的纯对映体与诱导的大鼠肝微粒体孵育，导致立体选择性地形成了一种迄今未知的代谢物，该代谢物仅在(+)-非索非那定的样品中检测到。对该化合物的初步结构解析表明，新代谢物很可能是N-去苯乙胺非索非那定的芳环羟基化衍生物。
