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

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].

RO 4926219, MK-7264, AF219

DMSO: 10 mg/mL (28.3 mM), pH is adjusted to 3 with HCl.

H2O: Insoluble