IN VIVO METABOLIC ACTIVATION OF CLOPIDOGREL IS INTESTINAL OR HEPATIC CYTOCHROME

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。本研究旨在确定我们是否可以证明氯吡格雷（商品名为Plavidine）的主要激活部位。氯吡格雷是治疗和预防心脏病发作的重要药物。当冠状动脉疾病患者服用这种药物时，它会停止血小板的作用，防止冠状动脉完全阻塞和心脏病发作。在最近的一项研究中，我们发现并非所有患者对氯吡格雷的反应都相同。换句话说，氯吡格雷在某些患者中比在其他患者中更有效。在我们的研究中，对氯吡格雷的反应是通过测量血小板凝集百分比的血液测试来确定的。包括氯吡格雷在内的许多药物都需要一种酶（细胞色素P450 3A 4），这种酶存在于肝脏和小肠内衬细胞中，以便被代谢激活，从而使药物有效地发挥作用。目前尚不清楚氯吡格雷是否在肠衬里细胞或肝脏中代谢活化。本研究旨在确定氯吡格雷的代谢活化主要是通过肠道CYP 3A 4还是通过肝脏（肝脏系统）中的CYP 3A 4。我们将使用红霉素（一种已知的肝CYP 3A 4抑制剂）和葡萄柚汁（一种已知的肠CYP 3A 4抑制剂）。当这些药物与氯吡格雷联合使用时，我们可以通过测定CYP 3A 4活性的试验来确定氯吡格雷的活化途径。给予氯吡格雷和葡萄柚汁后，将使用咪达唑仑的血液水平来测量主要在小肠中对CYP 3A 4活性的抑制作用。红霉素呼气试验将用于测量红霉素给药后主要在肝脏中对CYP 3A 4活性的抑制。咪达唑仑试验和红霉素呼气试验对于我们确定氯吡格雷在何处代谢是必要的。这项研究招募了对氯吡格雷反应正常的成年人。受试者将被随机分配接受氯吡格雷和红霉素或氯吡格雷和葡萄柚汁。如果与氯吡格雷联合使用时，肝脏CYP 3A 4活性被红霉素抑制（通过呼吸试验测量），则预计氯吡格雷的代谢活化将被抑制（对血小板的反应将减弱），这表明氯吡格雷在肝脏中被激活。另一方面，我们知道葡萄柚汁是小肠中CYP 3A 4的抑制剂。如果肠道CYP 3A 4活性被葡萄柚汁抑制（通过咪达唑仑试验确定），则预计氯吡格雷的代谢活化将被抑制，这表明氯吡格雷在肠道细胞衬里中被激活。本研究将招募30例对氯吡格雷反应正常的受试者。每例受试者将随机平均分配至氯吡格雷和红霉素组或氯吡格雷和葡萄柚汁组。将在方案中概述的特定时间点进行血液采样，以测量血小板功能并测量给予葡萄柚汁后主要在小肠中的咪达唑仑f CYP 3A 4活性水平。.红霉素呼气试验将测量给予醋竹桃霉素后主要在肝脏中对CYP 3A 4活性的抑制。这两项检查对于我们确定氯吡格雷在何处代谢是必要的。氯吡格雷抑制是指当服用氯吡格雷时，血小板对氯吡格雷的反应不如不服用葡萄柚汁或醋竹桃霉素时有效。如果与氯吡格雷联合使用时，三乙酰竹桃霉素（通过呼气试验测量）抑制肝脏CYP 3A 4活性，则预计氯吡格雷的代谢活化将受到抑制（对血小板的反应将减弱），这表明氯吡格雷在肝脏中被激活。另一方面，我们知道葡萄柚汁是小肠中CYP 3A 4的抑制剂。如果肠道CYP 3A 4活性被葡萄柚汁抑制（通过咪达唑仑试验确定），则预计氯吡格雷的代谢活化将被抑制，这表明氯吡格雷在肠道细胞衬里中被激活。 本研究将招募30名年龄在18-60岁的男性和女性，年龄不限种族或人种，对氯吡格雷反应正常。他们将被随机平均分配到氯吡格雷和三乙酰竹桃霉素组或氯吡格雷和葡萄柚汁组。将在各组的不同时间点进行血液检查，以确定氯吡格雷的活化部位。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This study is designed to determine if we can demonstrate where the medication clopidogrel (sold under the trade name of Plavix) is primarily activated. Clopidogrel is an important drug for the treatment and prevention of heart attacks. When patients with coronary artery disease take this drug, it stops the action of the platelets and prevents total coronary blockage and heart attacks. In a recent study we found that not all patients respond to clopidogrel the same way. In other words, in some patients clopidogrel was more effective than in others. In our studies, the response to clopidogrel is determined by a blood test that measures percent platelet clumping. Many drugs including clopidogrel require an enzyme (cytochrome P450 3A4), which is found in both the liver and the cells lining the small intestine, in order to be metabolically activated so the drugs can work effectively. It is not known whether clopidogrel is metabolically activated in the intestinal lining cells or in the liver. This study has been designed to determine whether the metabolic activation of clopidogrel is primarily by the intestinal CYP3A4 or by the CYP3A4 in the liver (hepatic system). We will use Erythromycin which is a known inhibitor of hepatic CYP3A4 and grapefruit juice which is a known inhibitor of intestinal CYP3A4. When these are taken in combination with clopidogrel, we can determine the route of activation of clopidogrel by doing tests that measure the activity of CYP3A4. Blood levels of midazolam will be used to measure the inhibition of CYP3A4 activity primarily in the small intestine after clopidogrel and grapefruit juice is given. The erythromycin breath test will be used to measure the inhibition of CYP3A4 activity primarily in the liver after Erythromycin is given. Both the midazolam test and the erythromycin breath test are necessary for us to determine where clopidogrel is metabolized. This study recruits adults who respond normally to clopidogrel. Participants will be randomly assigned to receive either clopidogrel and Erythromycin or clopidogrel and grapefruit juice. If the hepatic CYP3A4 activity is inhibited by Erythromycin (as measured by the breath test) when taken in combination with clopidogrel, it is expected that metabolic activation of clopidogrel will be inhibited (response on platelets will be diminished) and would indicate that clopidogrel is activated in the liver. On the other hand, we know that grapefruit juice is an inhibitor of CYP3A4 in the small intestine. If the intestinal CYP3A4 activity is inhibited by grapefruit juice (which is determined by the midazolam test) it is expected that metabolic activation of clopidogrel will be inhibited and would indicate that clopidogrel is activated in the intestinal cell lining. This study will recruit 30 subjects who respond normally to clopidogrel. Each subject will be randomly assigned equally to either the clopidogrel and Erythromycin or clopidogrel and grapefruit juice. Blood sampling will be performed at specific timepoints outlined in the protocol to measure platelet function and to measure levels of midazolam.f CYP3A4 activity primarily in the small intestine after grapefruit juice is given. . The erythromycin breath test will measure the inhibition of CYP3A4 activity primarily in the liver after troleandomycin is given. Both of these tests are necessary for us to determine where clopidogrel is metabolized. Clopidogrel inhibition means that when taken, the response of the platelets to clopidogrel is not as effective as it would be without the grapefruit juice or troleandomycin. If the hepatic CYP3A4 activity is inhibited by troleandomycin (measured by the breath test) when taken in combination with clopidogrel, it is expected that metabolic activation of clopidogrel will be inhibited (response on platelets will be diminished) and would indicate that clopidogrel is activated in the liver. On the other hand, we know that grapefruit juice is an inhibitor of CYP3A4 in the small intestine. If the intestinal CYP3A4 activity is inhibited by grapefruit juice (which is determined by the midazolam test) it is expected that metabolic activation of clopidogrel will be inhibited and would indicate that clopidogrel is activated in the intestinal cell lining. This study will recruit 30 males and females aged 18-60 of any ethnic origin or race who respond normally to clopidogrel. They will be randomly assigned equally to either the clopidogrel and troleandomycin group or clopidogrel and grapefruit juice group. Blood tests will be performed in various time points in each group to determine the site of activation of clopidogrel.