Uchida Yasuo, Wakayama Kentaro, Ohtsuki Sumio, Chiba Masato, Ohe Tomoyuki, Ishii Yasuyuki, Terasaki Tetsuya
Division of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical Sciences, Tohoku University, Miyagi, Japan (Y.U., T.T.); Department of Drug Metabolism, Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd., Ibaraki, Japan (K.W., M.C., T.O., Y.I.); and Department of Pharmaceutical Microbiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan (S.O.).
Division of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical Sciences, Tohoku University, Miyagi, Japan (Y.U., T.T.); Department of Drug Metabolism, Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd., Ibaraki, Japan (K.W., M.C., T.O., Y.I.); and Department of Pharmaceutical Microbiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan (S.O.)
J Pharmacol Exp Ther. 2014 Sep;350(3):578-88. doi: 10.1124/jpet.114.214536. Epub 2014 Jun 19.
The aim of this study was to investigate whether in vivo drug distribution in brain in monkeys can be reconstructed by integrating four factors: protein expression levels of P-glycoprotein (P-gp)/multidrug resistance protein 1 at the blood-brain barrier (BBB), in vitro transport activity per P-gp molecule, and unbound drug fractions in plasma and brain. For five P-gp substrates (indinavir, quinidine, loperamide, paclitaxel, and verapamil) and one nonsubstrate (diazepam), in vitro P-gp transport activities were determined by measuring transcellular transport across monolayers of cynomolgus monkey P-gp-transfected LLC-PK1 and parental cells. In vivo P-gp functions at the BBB were reconstructed from in vitro P-gp transport activities and P-gp expression levels in transfected cells and cynomolgus brain microvessels. Brain-to-plasma concentration ratios (Kp,brain) were reconstructed by integrating the reconstructed in vivo P-gp functions with drug unbound fractions in plasma and brain. For all compounds, the reconstructed Kp,brain values were within a 3-fold range of observed values, as determined by constant intravenous infusion in adult cynomolgus monkeys. Among four factors, plasma unbound fraction was the most sensitive factor to species differences in Kp,brain between monkeys and mice. Unbound brain-to-plasma concentration ratios (Kp,uu,brain) were reconstructed as the reciprocal of the reconstructed in vivo P-gp functions, and the reconstructed Kp,uu,brain values were within a 3-fold range of in vivo values, which were estimated from observed Kp,brain and unbound fractions. This study experimentally demonstrates that brain distributions of P-gp substrates and nonsubstrate can be reconstructed on the basis of pharmacoproteomic concept in monkeys, which serve as a robust model of drug distribution in human brain.
血脑屏障（BBB）处P-糖蛋白（P-gp）/多药耐药蛋白1的蛋白表达水平、每个P-gp分子的体外转运活性以及血浆和脑内的游离药物分数。对于五种P-gp底物（茚地那韦、奎尼丁、洛哌丁胺、紫杉醇和维拉帕米）和一种非底物（地西泮），通过测量跨食蟹猴P-gp转染的LLC-PK1单层细胞和亲本细胞的跨细胞转运来确定体外P-gp转运活性。根据体外P-gp转运活性以及转染细胞和食蟹猴脑微血管中的P-gp表达水平重建BBB处的体内P-gp功能。通过将重建的体内P-gp功能与血浆和脑内的药物游离分数相结合来重建脑-血浆浓度比（Kp,brain）。对于所有化合物，重建的Kp,brain值在通过成年食蟹猴恒速静脉输注测定的观测值的3倍范围内。在四个因素中，血浆游离分数是对猴子和小鼠之间Kp,brain物种差异最敏感的因素。游离脑-血浆浓度比（Kp,uu,brain）被重建为重建的体内P-gp功能的倒数，重建的Kp,uu,brain值在根据观测的Kp,brain和游离分数估计的体内值的3倍范围内。本研究通过实验证明，基于药代蛋白质组学概念可以在猴子中重建P-gp底物和非底物的脑分布，猴子是人类脑内药物分布的有力模型。
