SB 218795 is a potent and selective non-peptide NK3 receptor antagonist, with a Ki 13 nM for hNK3. SB 218795 shows about 90-fold and 7000-fold selectivity for hNK3 over hNK2 and hNK1, respectively. SB 218795 can inhibit NK3 receptor-mediated pupillary constriction of the rabbit[1][2].