Ontogeny of Voriconazole Pharmaockinetics and Metabolism

描述(申请人提供)：儿童曲霉病死亡率超过50%。伏立康唑是治疗这种感染的一线药物，我们已经证明伏立康唑的血药浓度与存活率之间存在非常显著的关系。然而，伏立康唑的剂量目前是经验的，儿童之间的血浆暴露差异为400%或更多，即使在静脉注射后也是如此。最多的是，这种变异的40%是由CYP2C19基因决定的。因此，量化年龄和疾病对代谢伏立康唑90%的CYP2C19、CYP3A4和黄素单加氧酶3(FMO3)表型活性的影响，并优化和合理地给药是至关重要的。近一半的治疗药物是由CYP2C19和CYP3A4代谢的，而FMO3广泛的底物特异性表明其在儿科药物治疗中的作用被忽视，伏立康唑就是最近的一个例子。因此，我们的实验室和统计学方法的新组合将为改变儿科药物开发和治疗剂量的方法奠定基础。我们的创新和跨学科建议的假设是，CYP2C19、CYP3A4和FMO3的个体发育将与观察到的伏立康唑PK的年龄相关变化显著相关，并将对最快达到与生存相关的伏立康唑血药浓度的剂量和策略产生重大影响。该项目有三个具体目标：1)表征儿童和青少年中纵向的CYP2C19、CYP3A4和FMO3表型；2)使用经验和生理模型描述伏立康唑PK；以及3)使用基于模型的贝叶斯自适应控制来优化患者伏立康唑的剂量。我们将招募60名需要伏立康唑的儿童/青少年参加I/II期PK研究，按年龄分层，2-12岁(n=10)，2-12岁(n=25)和12-18岁(n=25)。所有患者将从静脉(IV)剂量开始，并在临床指征时过渡到口服剂量。我们将从每个患者身上收集以下信息：1)血液样本，用于检测几个已知影响酶活性的CYP2C19和FMO3 SNP；2)静脉注射和口服后多达9个稳态PK血液样本；3)在服药后2小时进行2次随访的单一PK血液样本。在PK采样前静脉注射伏立康唑的同时，我们还将单独静脉注射微量埃索美拉唑、咪达唑仑和雷尼替丁作为鸡尾酒，分别检测CYP2C19、CYP3A4和FOM3的活性。我们将在口服PK访问和两次后续访问之前重复口服剂量的鸡尾酒。我们将使用探针药物代谢物与血浆时间浓度曲线(AUC)下母体面积的比率来估计DME表型，并同时定量外周血单个核细胞DME mRNA和蛋白。我们将测试DME表型、信使核糖核酸、蛋白质、伏立康唑PK参数、年龄、性别和疾病程度之间的关系。

DESCRIPTION (provided by applicant): Mortality in children from aspergillosis is more than 50%. Voriconazole is the first-line therapy for this infection, and we have shown a highly significant relationship between voriconazole plasma concentrations and survival. However, voriconazole dosing is currently empirical, and plasma exposure varies between children by 400% or more, even after intravenous dosing. At most, CYP2C19 genotype accounts for 40% of this variability. Therefore it is crucial to quantify the impact of age and illness on the phenotypc activity of CYP2C19, CYP3A4 and flavin mono-oxygenase 3 (FMO3), which together metabolize >90% of voriconazole, and to optimally and rationally dose this critical drug. CYP2C19 and CYP3A4 metabolize nearly half of therapeutic drugs, while the broad substrate specificity of FMO3 suggests its role in pediatric pharmacotherapy has been overlooked, voriconazole serving as a recent example. Therefore, our novel combination of laboratory and statistical methods will set the stage for paradigm-changing methods of pediatric drug development and therapeutic dosing. The hypothesis of our innovative and cross-disciplinary proposal is that the ontogeny of CYP2C19, CYP3A4 and FMO3 will significantly correlate with observed age-related changes in voriconazole PK and will have a major impact on dosing and strategies to most rapidly achieve voriconazole plasma concentrations that are associated with survival. There are three Specific Aims for the project: 1) to characterize the longitudinal CYP2C19, CYP3A4, and FMO3 phenotypes in children and adolescents; 2) to describe voriconazole PK using empirical and physiological models; and 3) to optimize patient voriconazole dosing with model-based Bayesian adaptive control. We will enroll 60 children/adolescents requiring voriconazole in a phase I/II PK study, stratified by age under 2 years (n=10), 2-12 years (n=25) and 12-18 years (n=25). All patients will begin with intravenous (IV) dosing and transition to oral dosing when clinically indicated. From each patient we will collect the following: 1) a blood sample for detection of several CYP2C19 and FMO3 SNPs known to affect enzyme activity; 2) up to 9 steady-state PK blood samples after IV and oral doses; and 3) single PK blood samples 2 hours post-dose at 2 follow-up visits. At the time of the IV voriconazole dose prior to the PK sampling, we will also give single IV microdoses of esomeprazole, midazolam, and ranitidine as a cocktail to probe CYP2C19, CYP3A4, and FOM3 activity, respectively. We will repeat this cocktail with oral doses before the oral PK visit and two follow-up visits. We will estimate DME phenotype using ratios of probe drug metabolite and parent areas under the plasma time concentration curves (AUCs) and simultaneously quantify peripheral blood mononuclear cell DME mRNA and protein. We will test associations between DME phenotype, mRNA, protein, voriconazole PK parameters, age, sex, and degree of illness.