HEMOLYTIC ANEMIA STUDIES OF HEMOLYTIC ANEMIA

溶血性贫血 溶血性贫血的研究

• 批准号: 2445112
• 负责人: DAVID J. JOLLOW
• 金额: $ 23.9万
• 依托单位: MEDICAL UNIVERSITY OF SOUTH CAROLINA
• 依托单位国家: 美国
• 财政年份: 1983
• 资助国家: 美国
• 起止时间: 1983-07-01 至 1999-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2445112
• 关键词: blood /lymphatic pharmacology; blood toxicology; chromium; cimetidine; dapsone; dosage; drug adverse effect; drug metabolism; erythrocytes; free radical oxygen; hemolytic anemia; hemotoxin; high performance liquid chromatography; human subject; ketoconazole; laboratory rat; membrane proteins; methemoglobin; oxidative stress; radiotracer; species difference; spectrometry; thiols; toxin metabolism; trimethoprim

The clinical use of dapsone has expanded over the last decade. Dapsone is now the drug of choice for certain autoimmune-associated disorders such as dermatitis herpetiformis, and is an important component of prophylaxis and chemotherapy for opportunistic infections, such as P. carnii pneumonia, in AIDS patients. In both situations, dapsone's hemotoxicity; viz, methemoglobinemia and hemolytic anemia, are dose limiting in therapy. Over the life of this grant, we have used a rat model to identify the hemotoxic metabolites (N-hydroxydapsone [DDS-NOH] and N-acetyl-N-hydroxydapsone [MADDS-NOH]) of the drug and to gain insight into the mechanism underlying the hemolytic response. We now propose to test the hypothesis that the insight gained with the rat model can be used to reduce the severity of dapsone-induced hemotoxicity in humans and hence improve the therapeutic ratio of the drug. Four aims are presented. The first will examine whether the mechanistic concepts developed with rat red cells applies to human cells, and if so, the relative responsiveness of human vs rat red cells. Parameters to be examined include heme oxidation (methemoglobin formation); oxy- and/or thiyl-radical production; glutathione and protein mixed disulfide formation (G-SS-G and Pr-SS-G); formation of hemoglobin- skeletal protein adducts and of other membrane-bound hemoglobin monomers and polymers; echinocyte formation; and susceptibility to macrophage ingestion. The second aim will characterize the effect of inhibitors of dapsone N-hydroxylation in rat hepatic microsomal preparations and, for selected inhibitors, on dapsone N-hydroxylation in the acute and chronic rat models of dapsone hemotoxicity, as a prelude to the clinical studies. The third aim will determine if the severity of hemotoxicity in volunteers and patients receiving single doses of dapsone can be correlated with blood levels of DDS-NOH+MADDS-NOH, and with their CYP3A4 phenotypic status. The fourth aim will examine she capacity of inhibitors of CYP3A4 (which has been implicated in the N-hydroxylation of dapsone in humans) to suppress both blood DDS-NOH+MADDS-NOH levels and hemotoxicity. Potential inhibitors to be tested include cimetidine, ketaconazole, grapefruit juice, and trimethoprim. Further studies will determine if the extent of binding of hemoglobin monomers and polymers to membrane components can be used to develop a quantitative assay to assess the severity of a hemolytic response occurring in patients during chronic dapsone therapy.

氨苯砜的临床应用在过去十年中有所扩大。氨苯砜 现在，某些自身免疫相关疾病的药物选择， 疱疹样皮炎，是预防的重要组成部分， 化疗的机会性感染，如P. carnii肺炎， 艾滋病患者。在这两种情况下，氨苯砜的血液毒性，即， 高铁血红蛋白血症和溶血性贫血在治疗中是剂量限制性的。超过 在这项资助的生命中，我们使用了大鼠模型来识别血液毒性， 代谢产物（N-羟基氨苯砜[DDS-NOH]和N-乙酰基-N-羟基氨苯砜 [MADDS-NOH]）的药物，并深入了解其机制 溶血反应。我们现在提出检验假设， 用大鼠模型获得的见解可用于降低 氨苯砜诱导的人类血液毒性，从而改善治疗 药物的比例。提出了四个目标。第一个问题是， 用大鼠红细胞开发的机械概念适用于人类 细胞，如果是这样，人与大鼠红细胞的相对反应性。 待检查的参数包括血红素氧化（高铁血红蛋白 形成）;氧和/或硫基自由基的产生;谷胱甘肽和蛋白质 混合二硫化物形成（G-SS-G和Pr-SS-G）;血红蛋白形成- 骨骼蛋白加合物和其他膜结合血红蛋白单体 和聚合物;棘细胞形成;和对巨噬细胞的易感性 摄入第二个目的将描述抑制剂的作用， 大鼠肝微粒体制备物中的氨苯砜N-羟基化， 选择的抑制剂，对氨苯砜N-羟基化的急性和慢性 氨苯砜血液毒性的大鼠模型，作为临床研究的前奏。 第三个目标是确定志愿者血液毒性的严重程度 接受单剂量氨苯砜的患者可能与 DDS-NOH+MADDS-NOH的血液水平，以及其CYP 3A 4表型 status.第四个目标是研究CYP 3A 4抑制剂的能力 （它与人体内氨苯砜的N-羟基化有关）， 抑制血液DDS-NOH+MADDS-NOH水平和血液毒性。潜在 待测试的抑制剂包括西咪替丁、酮他康唑、葡萄柚 果汁和甲氧苄啶进一步的研究将确定 血红蛋白单体和聚合物与膜组分的结合可以 用于开发定量测定，以评估溶血性 在慢性氨苯砜治疗过程中发生的反应。