YM-344031 is an orally administered antagonist targeting CCR3. It effectively inhibits the binding of Eotaxin-1 and RANTES to CCR3, with IC50 values of 3.0 and 16.3 nM, respectively. YM-344031 also suppresses ligand-induced increases in intracellular Ca [2+] levels and chemotaxis, alters eosinophil morphology induced by eotaxin-1 in macaque blood, and prevents allergic skin reactions in a mouse allergy model .