Small Molecule Quantification by Liquid Chromatography-Mass Spectrometry for Metabolites of Drugs and Drug Candidates
作者:Upendra P. Dahal、Jeffrey P. Jones、John A. Davis、Dan A. Rock
DOI:10.1124/dmd.111.040865
日期:2011.12
Identification and quantification of the metabolites of drugs and drug candidates are routinely performed using liquid chromatography-mass spectrometry (LC-MS). The best practice is to generate a standard curve with the metabolite versus the internal standard. However, to avoid the difficulties in metabolite synthesis, standard curves are sometimes prepared using the substrate, assuming that the signal for substrate and the metabolite will be equivalent. We have tested the errors associated with this assumption using a series of very similar compounds that undergo common metabolic reactions using both conventional flow electrospray ionization LC-MS and low-flow captive spray ionization (CSI) LC-MS. The differences in standard curves for four different types of transformations (O-demethylation, N-demethylation, aromatic hydroxylation, and benzylic hydroxylation) are presented. The results demonstrate that the signals of the substrates compared with those of the metabolites are statistically different in 18 of the 20 substrate-metabolite combinations for both methods. The ratio of the slopes of the standard curves varied up to 4-fold but was slightly less for the CSI method.
药物及药物候选物代谢物的鉴定和定量通常使用液相色谱-质谱联用技术 (LC-MS) 进行。最佳实践是生成以代谢物与内标的标准曲线。然而,为了避免代谢物合成的困难,有时会使用底物来准备标准曲线,假设底物和代谢物的信号是等效的。我们使用一系列非常相似的化合物,这些化合物经历共同的代谢反应,测试了这一假设所带来的误差,采用了传统流动电喷雾电离 LC-MS 和低流量捕获喷雾电离 (CSI) LC-MS 方法。文中展示了四种不同转化类型(O-去甲基化、N-去甲基化、芳香族羟基化和苄基羟基化)的标准曲线差异。结果表明,在20种底物-代谢物组合中的18种情况下,两种方法中底物和代谢物的信号在统计上是显著不同的。标准曲线的斜率比率最高可变化4倍,但CSI方法的变化略小。