Metabolic Consequences of HAART: CYP3A and P-gp

人类免疫缺陷病毒蛋白酶抑制剂(HIV PI)作为多种药物治疗的组成部分，与其他高效抗逆转录病毒疗法(HAART)一起，已经深刻地改变了HIV感染者的预后和生活质量。尽管如此，PI和其他HAART药物并不能治愈艾滋病毒，病毒载量(可能具有耐药形式)从病毒库中死灰复燃(“突破”)仍然是一个持续关注的临床问题。药物动力学可变性--尤其是导致一种或多种HAART药物处于低水平或无法检测到水平的时期--可能容易出现突破和耐药。变异的一个主要来源是HAART药物的动力学与人细胞色素P450-3A(CyP3A)亚型(调节HAART药物本身和许多其他化合物的代谢)以及P-糖蛋白(P-gp)的关系，P-糖蛋白是一种定位于胃肠道粘膜和血脑屏障的运输蛋白。许多重要的HAART药物是CYP3A和/或P-gp的抑制剂和/或诱导剂，产生涉及自身新陈代谢(即自我诱导)的复杂且依赖时间的相互作用，以及与其他联合给药类别的相互作用。HIV PI以及可能的其他HAART成分对CYP3A的调节失调与HIV的代谢后果有关，如脂肪营养不良、胰岛素抵抗和高脂血症。本建议利用相关的临床和分子技术，以派利托那韦为指标化合物，提供有关HAART组分与细胞色素P3A和P-gp相互作用的程度、时间进程和后果的明确数据。答：在临床研究中，咪达唑仑(静脉注射和口服)被用作探针CYP3A底物，以确定在以下情况下利托那韦对肝脏和胃肠细胞色素P3A功能的影响：对照组，在利托那韦暴露之前；急性利托那韦暴露(抑制)；在利托那韦长期暴露期间(联合诱导和抑制)；在延长利托那韦暴露之后(仅诱导)。以非索非那定为指标底物进行了P-gp调控的平行研究。B.人腺癌细胞培养模型将基于免疫定量技术和荧光探针对P-gp依赖细胞排斥的功能分析，评估HAART药物上调P-gp的时间过程和浓度依赖性。这一多学科的建议为评估目前可用的和实验性的HAART药物对人类CYP3A和P-gp的影响提供了临床和科学基础。

The human immunodeficiency viral protease inhibitors (HIV PIs), as a component of multiple drug therapy with other Highly Active Anti- Retroviral Therapies (HAART), have profoundly changed the prognosis and quality of life for individuals with HIV infection. Nonetheless PIs and other HAART drugs are not curative of HIV, and resurgence of viral load (possibly with resistant forms) from viral reservoirs ("breakthrough") remains a clinical problem of ongoing concern. Pharmacokinetic variability - - particularly that leading to periods of low or undetectable levels of one or more HAART drugs - - may predispose to breakthrough and resistance. One major source of variability derives from the relation of the kinetics of HAART drugs to the human Cytochrome P450-3A (CYP3A) isoforms, which mediate the metabolism of the HAART drugs themselves and many other compounds, and to P- glycoprotein (P-gp), a transport protein localized in GI tract mucosa and the blood-brain barrier. Many of the important HAART drugs are inhibitors and/or inducers of CYP3A and/or of P-gp, producing complex and time-dependent interactions involving their own metabolism (i.e.,autoinduction) as well as interactions with other coadministered classes of medications. Dysregulation of CYP3A by HIV PIs, and possibly other HAART components, has been linked to metabolic consequences of HIV such as lipodystrophy, insulin resistance, and hyperlipidemia. The present proposal utilizes related clinical and molecular techniques to provide definitive data on the extent, time course, and consequences of the interaction of HAART components with CYP3A and P-gp, using the PI ritonavir as the index compound. A. In clinical studies, midazolam (given I.V. and orally) is used as a probe CYP3A substrate to determine the effects of ritonavir on hepatic and gastrointestinal CYP3A function under the following conditions: control, prior to ritonavir exposure; with acute ritonavir exposure (inhibition); during extended ritonavir exposure (combined induction and inhibition); following extended ritonavir exposure (induction only). Parallel studies of P-gp regulation are performed using fexofenadine as the index substrate. B. A human adenocarcinoma cell culture model will evaluate the time-course and concentration-dependence of P-gp upregulation by HAART drugs, based on immunoquantitative techniques as well as functional assays of P-gp dependent cell exclusion of a fluorescent probe. This multidisciplinary proposal provides a clinical and scientific basis to assess the effects of currently available as well as experimental HAART medications on human CYP3A and P-gp.