Astemizole-d3 is the deuterium labeled Astemizole. Astemizole (R 43512), a second-generation antihistamine drug to diminish allergic symptoms with a long duration of action, is a histamine H1-receptor antagonist, with an IC50 of 4 nM. Astemizole also shows potent hERG K+ channel blocking activity with an IC50 of 0.9 nM. Astemizole has antipruritic effects[1][2].
