Chen Weiqing, Yang Jerry Z, Andersen Rikke, Nielsen Lisbeth H, Borchardt Ronald T
Department of Pharmaceutical Chemistry, The University of Kansas, 2095 Constant Avenue, Lawrence, KS 66047, USA.
J Pharmacol Exp Ther. 2002 Nov;303(2):849-57. doi: 10.1124/jpet.102.037143.
The permeation characteristics of a model opioid peptide, H-Tyr-D-Ala-Gly-Phe-D-Leu-OH (DADLE), and its cyclic prodrugs [acyloxyalkoxy-based cyclic prodrug of DADLE (AOA-DADLE), coumarinic acid-based cyclic prodrug of DADLE (CA-DALE), and oxymethyl-modified coumarinic acid-based cyclic prodrug of DADLE (OMCA-DADLE)] across the blood-brain barrier (BBB) were determined using an in situ perfused rat brain model. The rat brains were perfused with Krebs-bicarbonate buffer containing test compounds in the absence or presence of a specific P-glycoprotein inhibitor (GF-120918). Brain samples were collected after perfusion and processed by a capillary depletion method. After liquid phase extraction with acetonitrile, samples were analyzed using high-performance liquid chromatography with tandem mass spectrometric detection. Linear uptake kinetics of DADLE and its cyclic prodrugs was observed within the range of 60 to 240 s of perfusion. The apparent permeability coefficient (P(app)) of DADLE across the BBB was very low (<10(-7) cm/s), probably due to its unfavorable physicochemical properties (e.g., charge, hydrophilicity, and high hydrogen-bonding potential). All three cyclic prodrugs, however, also exhibited low membrane permeation (P(app) <10(-7) cm/s) in spite of their more favorable physicochemical properties (e.g., no charge, high hydrophobicity, and low hydrogen-bonding potential). Inclusion of GF-120918 (10 microM) in the perfusates fully inhibited the P-gp activity in the BBB and dramatically increased the P(app) values of AOA-DADLE, CA-DADLE, and OMCA-DADLE by approximately 50-, 460-, and 170-fold, respectively. In contrast, GF-120918 had no effect on the P(app) value of DADLE. In addition, the observed bioconversions of the prodrugs to DADLE in the rat brains after 240-s perfusion were very low (5.1% from AOA-DADLE, 0.6% from CA-DADLE, and 0.2% from OMCA-DADLE), which was consistent with the in vitro bioconversion rates determined previously in rat brain homogenates.
使用原位灌注大鼠脑模型，测定了一种阿片样肽模型H-Tyr-D-Ala-Gly-Phe-D-Leu-OH（DADLE）及其环型前药[基于酰氧基烷氧基的DADLE环型前药（AOA-DADLE）、基于香豆酸的DADLE环型前药（CA-DALE）以及基于氧甲基修饰香豆酸的DADLE环型前药（OMCA-DADLE）]透过血脑屏障（BBB）的特性。在不存在或存在特异性P-糖蛋白抑制剂（GF-120918）的情况下，用含有受试化合物的Krebs-碳酸氢盐缓冲液灌注大鼠脑。灌注后收集脑样本，采用毛细管耗竭法进行处理。用乙腈进行液相萃取后，使用高效液相色谱-串联质谱检测法分析样本。在灌注60至240秒范围内，观察到DADLE及其环型前药呈线性摄取动力学。DADLE透过BBB的表观渗透系数（P(app)）非常低（<10(-7) cm/s），这可能归因于其不利的物理化学性质（如电荷、亲水性和高氢键潜力）。然而，尽管三种环型前药具有更有利的物理化学性质（如无电荷、高疏水性和低氢键潜力），它们的膜渗透性也很低（P(app) <10(-7) cm/s）。灌注液中加入GF-120918（10 microM）可完全抑制BBB中的P-糖蛋白活性，并使AOA-DADLE、CA-DADLE和OMCA-DADLE的P(app)值分别显著增加约50倍、460倍和170倍。相比之下，GF-120918对DADLE的P(app)值没有影响。此外，在240秒灌注后，观察到前药在大鼠脑中向DADLE的生物转化非常低（AOA-DADLE为5.1%，CA-DADLE为0. ,6%，OMCA-DADLE为0.2%），这与先前在大鼠脑匀浆中测定的体外生物转化率一致。
