Gefapixant (AF219) is a P2X3 receptor (P2X3R) antagonist with IC50 of ~30 nM at recombinant hP2X3 homotrimers and 100-250 nM at hP2X2/3 heterotrimeric receptors.

P2X2/3 heterotrimeric receptors (human):100-250 nM, Recombinant hP2X3 homotrimers:~30 nM

Gefapixant的IC50值报告为针对重组hP2X3同源三聚体约30 nM，以及针对hP2X2/3异源三聚体受体100-250 nM，其效力与报告中重组大鼠受体的相近，而且对任何不含P2X3亚单位的受体没有抑制作用（在重组同源三聚体hP2X1、hP2X2、hP2X4、rP2X5及hP2X7通道的IC50值均>>10,000 nM）。

在大鼠膝关节骨关节炎模型中（经单碘乙酸盐关节内注射14天后），Gefapixant通过口服给药（每日两次，连续7天）缓解了负重侧偏，并在两种较高剂量下完全逆转了明显的痛觉过敏 [2]。

A rodent model often employs for assessing the potential for drug effect in osteoarthritis (OA) pain is based on the intraarticular injection of monoiodoacetate (mIOA) into one knee joint of the rat. To measure the effect of Gefapixant on the weight bearing laterality and apparent hyperalgesia, Gefapixant is given by intraplantar or oral administration to the rats, with different concentrations (6, 20, and 60 mg/kg) two times a day and continues up to a week[2].