Department of Metabolism and Pharmacokinetics, Pharmaceutical Candidate Optimization, Bristol-Meyers Squibb, Princeton, New Jersey 08543-4000, USA.
Drug Metab Dispos. 2010 Jul;38(7):1072-82. doi: 10.1124/dmd.109.031518. Epub 2010 Apr 1.
17alpha-Ethinylestradiol (EE2), a component of oral contraceptives, is known to undergo considerable first-pass 3-O-sulfation in the intestine and liver. Once formed, the 3-O-sulfate conjugate (EE2-Sul) is detected in circulation at appreciable levels (versus parent EE2) and is present in bile. Therefore, hepatic uptake of EE2-Sul was assessed with suspensions of cryopreserved human primary hepatocytes. In this instance, there was evidence for active (temperature-dependent) uptake, which was described by a two-K(m) (Michaelis constant) model (K(m1) = 220 nM; K(m2) = 15.5 microM). Uptake was inhibited (approximately 90%) by bromosulfophthalein but not by tetraethylammonium or p-aminohippurate. In agreement, EE2-Sul was shown to be a substrate of recombinant organic anion transporter peptides (OATP1B1 and OATP2B1), and Na(+)/taurocholate-cotransporting polypeptide (NTCP), expressed individually in human embryonic kidney (HEK) 293 cells. Transport by OATP1B1 was described by two K(m) values (87 nM and 141 microM), whereas OATP2B1- and NTCP-mediated uptake into HEK-293 cells conformed to single K(m) kinetics (10.7 and 2.6 microM, respectively). EE2-Sul was also assessed as an efflux transporter substrate using membrane vesicles expressing bile salt export pump, breast cancer resistance protein (BCRP), and individual forms of multidrug resistance-associated protein (MRP1, MRP2, and MRP3). Transport studies were also conducted with a cell line expression P-glycoprotein. Only vesicles that contained BCRP exhibited ATP-dependent uptake of EE2-Sul (K(m1) = 2.9 and K(m2) = 307 microM). Collectively, the data show that hepatic uptake of EE2-Sul can be mediated by three transporters (OATP1B1, OATP2B1, and NTCP), whereas biliary excretion of EE2-Sul into bile likely involves BCRP.
17alpha-乙炔基雌二醇（EE2）是口服避孕药的一种成分，已知其在肠道和肝脏中会经历大量的 3-O-硫酸化首过代谢。一旦形成，3-O-硫酸酯结合物（EE2-Sul）就会以可观的水平（与母体 EE2 相比）在循环中被检测到，并存在于胆汁中。因此，使用冷冻保存的人原代肝细胞悬浮液评估了 EE2-Sul 的肝摄取。在这种情况下，有证据表明存在主动（温度依赖）摄取，这可以通过双 Km（米氏常数）模型来描述（Km1=220 nM；Km2=15.5 μM）。溴磺酞钠可抑制摄取（约 90%），但四乙铵或对氨基马尿酸盐不能抑制摄取。一致地，EE2-Sul 被证明是重组有机阴离子转运肽（OATP1B1 和 OATP2B1）和 Na+/牛磺胆酸钠共转运蛋白（NTCP）的底物，这些转运蛋白分别在人胚肾（HEK）293 细胞中表达。OATP1B1 的转运由两个 Km 值（87 nM 和 141 μM）描述，而 OATP2B1 和 NTCP 介导的 HEK-293 细胞摄取符合单 Km 动力学（分别为 10.7 和 2.6 μM）。EE2-Sul 也被评估为通过表达胆盐输出泵、乳腺癌耐药蛋白（BCRP）和多药耐药相关蛋白（MRP1、MRP2 和 MRP3）的各个形式的膜囊泡作为外排转运体底物。还进行了使用表达 P-糖蛋白的细胞系的转运研究。只有包含 BCRP 的囊泡表现出 EE2-Sul 的 ATP 依赖性摄取（Km1=2.9 和 Km2=307 μM）。总的来说，数据表明 EE2-Sul 的肝摄取可以由三种转运蛋白（OATP1B1、OATP2B1 和 NTCP）介导，而 EE2-Sul 排入胆汁的胆汁排泄可能涉及 BCRP。
