YM-344031 is an orally active antagonist for CCR3. YM-344031 inhibits binding of Eotaxin-1 and RANTES to CCR3 , with IC 50 of 3.0 and 16.3 nM. YM-344031 inhibits ligand-induced rise in intracellular Ca [2+] and the ligand-induced chemotaxis. YM-344031 inhibits eotaxin-1-induced changes in eosinophil morphology in macaques blood, and prevents allergic skin reactions in a mouse allergy model.