H4R antagonist 1 is a highly selective histamineH4receptor (H4R) antagonist (IC50: 27 nM). H4R antagonist 1 does not show any noticeable binding affinity to other subtypes of histaminereceptors, H1R, H2R, and H3R.
A-943931 is a histamineH4receptorantagonist (Ki= 3.8 nM).1In vivo, A-943931 inhibits scratching induced by clobenpropit in mice (ED50= 26 μmoles/kg, i.p.). 1.Milicic, I., Witte, D.G., Miller, T.L., et al.Identification of two potent and selective histamineH4receptorantagonists with antipruritic activityFASEB J.23(S1)760.768-760.768(2009)