作者:Jun Lu、Nuala Helsby、Brian D. Palmer、Malcolm Tingle、Bruce C. Baguley、Philip Kestell、Lai-Ming Ching
DOI:10.1124/jpet.104.067793
日期:2004.8
Thalidomide is increasingly important in clinical treatment, not only of various inflammatory conditions but also in multiple myeloma and other malignancies. Moreover, the metabolism of thalidomide varies considerably among different species, indicating a need to understand its mechanistic basis. Our previous in vivo studies showed the plasma half-life of thalidomide to be much shorter in mice than in humans, with rabbits showing intermediate values. We were unable to detect hydroxylated thalidomide metabolites in humans and suggested that interspecies differences in thalidomide hydroxylation might account for the differences in plasma half-life. We sought here to establish whether these species differences in the formation of hydroxylated thalidomide metabolites could be discerned from in vitro studies. Liver microsomes of mice, rabbit, and human donors were incubated with thalidomide and analyzed using liquid chromatography-mass spectrometry. Hydrolysis products were detected for all three species, and the rates of formation were similar to those for spontaneous hydrolysis, except in rabbits where phthaloylisoglutamine formation increased linearly with microsomal enzyme concentration. Multiple hydroxylation products were detected, including three dihydroxylated metabolites not observed in vivo. Thalidomide-5- O -glucuronide, detected in vivo, was absent in vitro. The amount of 5-hydroxythalidomide formed was high in mice, lower in rabbits, and barely detectable in humans. We conclude that major interspecies differences in hepatic metabolism of thalidomide relate closely to the rate of in vivo metabolite formation. The very low rate of in vitro and in vivo hydroxylation in humans strongly suggests that thalidomide hydroxylation is not a requirement for clinical anticancer activity.
沙利度胺在临床治疗中的作用日益重要,不仅适用于多种炎症性疾病,还在多发性骨髓瘤和其他恶性肿瘤的治疗中发挥作用。此外,沙利度胺在不同物种间的代谢差异显著,这表明有必要深入了解其机制基础。我们之前的动物实验研究表明,沙利度胺在血液中的半衰期在小鼠体内远短于人类,兔子则介于两者之间。我们在人体内未能检测到羟化的沙利度胺代谢产物,并提出不同物种间沙利度胺羟化作用的差异可能解释了血液中半衰期的差异。本文中,我们旨在探究通过体外研究是否能观察到这些物种间在生成羟化沙利度胺代谢物方面的差异。我们使用液相色谱-质谱联用法分析了小鼠、兔子和人类的肝脏微粒体与沙利度胺共同孵育后的产物。结果显示,三种物种均检测到水解产物,且形成速率与自发水解相近,惟兔子体内的邻苯二甲酰异谷氨酰胺形成速率随微粒体酶浓度增加呈线性上升。此外,还检测到了多种羟化产物,包括三种未在体内观察到的双羟化代谢物。体内检测到的沙利度胺-5-O-葡萄糖苷酸在体外实验中未见。5-羟基沙利度胺的生成量在小鼠中最高,兔子次之,人体内几乎无法检测。我们得出结论,沙利度胺在肝脏代谢中的主要物种间差异与其体内代谢产物的生成速率密切相关。人体内体外羟化速率极低,这一现象强烈暗示沙利度胺的羟化作用并非其临床抗癌活性的必要条件。