TAXOL DISPOSITION AND METABOLISM IN HUMANS

本建议的目的是加深对 研究表明， 这将与紫杉醇的临床试验平行进行， 晚期恶性肿瘤患者。 根据初步观察 我们一般的工作假设是多个过程（血液结合， 代谢，胆汁排泄）决定的交付和行动 以及与这些过程相互作用可能会影响 临床疗效和毒性。 这一假设将在体内进行检验 在体外，使用细胞和亚细胞制剂，在三个 相互关联的目标。 在目标1中，我们将建立紫杉醇的处置 在患者中，首次使用放射性标记药物。 的 紫杉醇的药代动力学，包括其血液结合、其代谢 其通过尿液和粪便途径的排泄将因此被 测定 尤其重要的是确定潜在剂量- 在这些过程中的依赖性，并建立一个完整的帐户， 紫杉醇剂量。 我们还将描述一个依赖于能量的 血小板对紫杉醇高亲和力摄取及其重要性 用于紫杉醇处置。 在目标2中，我们将讨论紫杉醇的代谢 在体外，使用人肝匀浆和微粒体。 定性 首先使用HPLC分离技术确定代谢结局 和串联质谱法。 我们接下来将确定动力学方面 紫杉醇代谢的程度和机制的潜在药物和 其他互动。 细胞色素P450同工酶的鉴别 所涉及的将完成与同工酶特异性抗体 （催化活性，Western分析）和稳定的cDNA表达 系统. 将测定紫杉醇代谢产物的生物活性 体外 在目标3中，我们将确定 药物与紫杉醇胆汁分泌的相互作用和紫杉醇 代谢物。 这将在作为人类模型的大鼠体内进行 以及在体外，使用胆小管膜囊泡进行研究 特定的主动运输过程。 特别重要的是 浓度依赖性研究和潜在的参与， 多药耐药转运蛋白（P-糖蛋白）。 总体看 拟议的研究将集中在紫杉醇的三个主要过程 处置，即，血液结合、代谢和胆汁分泌， 其中可能会对药物的疗效和毒性产生深远的影响 紫杉醇。

The objective of this proposal is to develop an improved understanding of the disposition of the antineoplastic drug taxol in humans in studies that will be conducted in parallel with clinical trials of taxol in patients with advanced malignancies. Based on preliminary observations our general working hypothesis is that multiple processes (blood binding, metabolism, biliary excretion) determine the delivery and actions of taxol in man and that interactions with these processes might affect the clinical efficacy and toxicity. This hypothesis will be tested in vivo and in vitro, using cells and subcellular preparations, in three interrelated Aims. In Aim 1 we will establish the disposition of taxol in patients, for the first time using radioactively labeled drug. The pharmacokinetics of taxol, including its blood binding, its metabolism and its excretion by the urinary and fecal routes will thus be determined. Of particular importance is to determine potential dose- dependency in these processes and to establish a complete account of administered taxol dose. We will also characterize an energy-dependent high affinity uptake of taxol by platelets and determine its importance for taxol disposition. In Aim 2 we will address the metabolism of taxol in vitro, using human liver homogenates and microsomes. The qualitative metabolic fate will first be established, using HPLC isolation techniques and tandem mass spectrometry. We will next determine the kinetic aspects of taxol metabolism and the extent and mechanisms of potential drug and other interactions. Identification of the cytochrome P450 isoenzyme(s) involved will be accomplished with isoenzyme-specific antibodies (catalytic activities, Western analysis) and stable cDNA expression systems. Biological activities of taxol metabolites will be determined in vitro. In Aim 3 we will determine the mechanism of and the potential drug interactions with the biliary secretion of taxol and taxol metabolites. This will be done in vivo in the rat as a model of humans as well as in vitro, using bile canalicular membrane vesicles for studies of specific active transport processes. Of particular importance is studies of concentration-dependency and the potential involvement of the multiple drug resistance transporter (P-glycoprotein). Overall, the proposed studies will focus on the three major processes governing taxol disposition, i.e., blood binding, metabolism and biliary secretion, each of which could have profound influence on the efficacy and toxicity of taxol.