XP13512 [(±)-1-([(α-Isobutanoyloxyethoxy)carbonyl] aminomethyl)-1-cyclohexane Acetic Acid], A Novel Gabapentin Prodrug: I. Design, Synthesis, Enzymatic Conversion to Gabapentin, and Transport by Intestinal Solute Transporters
作者:Kenneth C. Cundy、Russell Branch、Tania Chernov-Rogan、Tracy Dias、Toño Estrada、Karin Hold、Kerry Koller、Xiaoli Liu、Adam Mann、Matt Panuwat、Stephen P. Raillard、Shubhra Upadhyay、Quincey Q. Wu、Jia-Ning Xiang、Hui Yan、Noa Zerangue、Cindy X. Zhou、Ronald W. Barrett、Mark A. Gallop
DOI:10.1124/jpet.104.067934
日期:2004.10
Gabapentin is thought to be absorbed from the intestine of humans and animals by a low-capacity solute transporter localized in the upper small intestine. Saturation of this transporter at doses used clinically leads to dose-dependent pharmacokinetics and high interpatient variability, potentially resulting in suboptimal drug exposure in some patients. XP13512 [(±)-1-([(α-isobutanoyloxyethoxy)carbonyl] aminomethyl)-1-cyclohexane acetic acid] is a novel prodrug of gabapentin designed to be absorbed throughout the intestine by high-capacity nutrient transporters. XP13512 was stable at physiological pH but rapidly converted to gabapentin in intestinal and liver tissue from rats, dogs, monkeys, and humans. XP13512 was not a substrate or inhibitor of major cytochrome P450 isoforms in transfected baculosomes or liver homogenates. The separated isomers of XP13512 showed similar cleavage in human tissues. The prodrug demonstrated active apical to basolateral transport across Caco-2 cell monolayers and pH-dependent passive permeability across artificial membranes. XP13512 inhibited uptake of 14C-lactate by human embryonic kidney cells expressing monocarboxylate transporter type-1, and direct uptake of prodrug by these cells was confirmed using liquid chromatography-tandem mass spectrometry. XP13512 inhibited uptake of 3H-biotin into Chinese hamster ovary cells overexpressing human sodium-dependent multivitamin transporter (SMVT). Specific transport by SMVT was confirmed by oocyte electrophysiology studies and direct uptake studies in human embryonic kidney cells after tetracycline-induced expression of SMVT. XP13512 is therefore a substrate for several high-capacity absorption pathways present throughout the intestine. Therefore, administration of the prodrug should result in improved gabapentin bioavailability, dose proportionality, and colonic absorption compared with administration of gabapentin.
格拉克巴丁(Gabapentin)被认为通过位于小肠上部的低容量溶质转运蛋白从人类和动物的肠道吸收。在临床使用的剂量下,该转运蛋白的饱和会导致剂量依赖性的药物代谢动力学和较高的个体间变异,可能导致某些患者药物暴露不足。XP13512 [(±)-1-([(α-异丁酰氧)乙氧基]羧酰基)氨基甲基]-1-环己烷乙酸] 是一种新型的格拉克巴丁前药,旨在通过高容量营养物质转运蛋白在整个肠道被吸收。XP13512在生理pH下稳定,但在大鼠、犬、猴子和人类的肠道和肝脏组织中迅速转化为格拉克巴丁。XP13512不是转染的病毒体或肝脏匀浆中主要的细胞色素P450亚型的底物或抑制剂。XP13512的分离异构体在人体组织中表现出类似的裂解。该前药在Caco-2细胞单层中表现出主动的顶侧到基侧转运,并且在人工膜上显示出pH依赖性的被动通透性。XP13512抑制了人胚肾细胞中表达单羧酸转运蛋白类型1的14C-乳酸的摄取,并通过液相色谱-串联质谱确认了该细胞对前药的直接摄取。XP13512抑制了对过表达人类钠依赖性多维生素转运蛋白(SMVT)的中国仓鼠卵巢细胞中3H-生物素的摄取。通过卵母细胞电生理学研究和在经过四环素诱导SMVT表达的人胚肾细胞中进行的直接摄取研究,确认了SMVT的特异性转运。因此,XP13512是多条存在于肠道中的高容量吸收通路的底物。因此,前药的给药应当提高格拉克巴丁的生物利用度、剂量成比例性和结肠吸收,与直接给药格拉克巴丁相比。