A potent, selective, orally availale C5aR (CD88) inhibitor with IC50 of 0.1 nM; shows no activity (IC50 >5,000 nM)for C5aR-related receptors C5L2, C3aR, ChemR23, GPR1 and FPR1; inhibits C5a-mediated chemotaxis of U937 cells with pA2 of 0.2 nM; shows activity in mouse model of ANCA-induced glomerulonephritis.