A Novel In Vivo Receptor Occupancy Methodology for the Glucocorticoid Receptor: Toward An Improved Understanding of Lung Pharmacokinetic/Pharmacodynamic Relationships
作者:Elin Boger、Pär Ewing、Ulf G. Eriksson、Britt-Marie Fihn、Michael Chappell、Neil Evans、Markus Fridén
DOI:10.1124/jpet.114.221226
日期:2015.5
Investigation of pharmacokinetic/pharmacodynamic (PK/PD) relationships for inhaled drugs is challenging because of the limited possibilities of measuring tissue exposure and target engagement in the lung. The aim of this study was to develop a methodology for measuring receptor occupancy in vivo in the rat for the glucocorticoid receptor (GR) to allow more informative inhalation PK/PD studies. From AstraZeneca’s chemical library of GR binders, compound 1 [ N -(2-amino-2-oxo-ethyl)-3-[5-[(1 R ,2 S )-2-(2,2-difluoropropanoylamino)-1-(2,3-dihydro-1,4-benzodioxin-6-yl)propoxy]indazol-1-yl]- N -methyl-benzamide] was identified to have properties that are useful as a tracer for GR in vitro. When given at an appropriate dose (30 nmol/kg) to rats, compound 1 functioned as a tracer in the lung and spleen in vivo using liquid chromatography–tandem mass spectrometry bioanalysis. The methodology was successfully used to show the dose-receptor occupancy relationship measured at 1.5 hours after intravenous administration of fluticasone propionate (20, 150, and 750 nmol/kg) as well as to characterize the time profile for receptor occupancy after a dose of 90 nmol/kg i.v. The dose giving 50% occupancy was estimated as 47 nmol/kg. The methodology is novel in terms of measuring occupancy strictly in vivo and by using an unlabeled tracer. This feature confers key advantages, including occupancy estimation not being influenced by drug particle dissolution or binding/dissociation taking place postmortem. In addition, the tracer may be labeled for use in positron emission tomography imaging, thus enabling occupancy estimation in humans as a translatable biomarker of target engagement.
吸入药物的药代动力学/药效学(PK/PD)关系研究具有挑战性,因为在肺部测量组织暴露和靶点参与的可能性有限。本研究的目的是开发一种测量大鼠体内糖皮质激素受体(GR)的受体占用率的方法,以便进行更翔实的吸入 PK/PD 研究。在阿斯利康的 GR 结合剂化学库中,化合物 1 [ N -(2-氨基-2-氧代-乙基)-3-[5-[(1 R,2 S )-2-(2,2-difluoropropanoylamino)-1-(2,3-dihydro-1,4-benzodioxin-6-yl)propoxy]indazol-1-yl]- N -methyl-benzamide] 被确定具有可作为 GR 体外示踪剂的特性。采用液相色谱-串联质谱生物分析法,在给大鼠服用适当剂量(30 nmol/kg)时,化合物 1 在体内肺部和脾脏中发挥了示踪剂的作用。该方法成功用于显示静脉注射丙酸氟替卡松(20、150 和 750 nmol/kg)1.5 小时后测得的剂量-受体占有率关系,并描述了静脉注射 90 nmol/kg 剂量后受体占有率的时间曲线。该方法在严格的体内测量受体占用率方面具有创新性,而且使用的是未标记的示踪剂。这一特点带来了一些关键优势,包括占用率估算不受药物颗粒溶解或死后结合/解离的影响。此外,示踪剂还可标记用于正电子发射断层扫描成像,从而使人体占用率估计成为靶标参与的可转化生物标志物。