[D-Trp2,7,9] Substance P is a tachykinin (Neurokinin Receptor) antagonist with Ki values of 1 μM, 1.3 μM, and ~9 μM for NK-1, NK-2,and NK-3 receptor, respectively[1].
IC 50
NK1: 1 μM (Ki); NK2: 1.3 μM (Ki); NK3: ~9 μM (Ki)
References
[1] S H Buck, et al. Agonist and antagonist binding to tachykinin peptide NK-2 receptors. Life Sci. 1988;42(26):2701-8. DOI:10.1016/0024-3205(88)90246-9