H4R antagonist 1 is a highly selective histamine H4 receptor (H4R) antagonist (IC50: 27 nM). H4R antagonist 1 does not show any noticeable binding affinity to other subtypes of histamine receptors, H1R, H2R, and H3R.

H4 receptor (human):27 nM, H4 receptor (mouse):290 nM

The competitive binding assay against a wider panel of GPCR, ion channel, and transporters at the concentration of 10 μM reveals that H4R antagonist 1 ?is highly selective for H4R.?The inhibitory activity of H4R antagonist 1 against mouse H4R (IC50=0.29 μM) is about 10 times weaker than that for human H4R.

In the GTPγS functional assay, H4R antagonist 1 shows inhibitory activity against mouse H4R with an IC50 of 0.69 μM.H4R antagonist 1 shows significant antipruritic and anti-inflammatory efficacy in Oxazolone-induced murine model mimicking human atopic dermatitis (AD).