[Phe1ψ(CH2-NH)Gly2]Nociceptin(1-13)NH2 (cas# 213130-17-7) is a useful research chemical.[Phe1ψ(CH2-NH)Gly2]Nociceptin(1-13)NH2 is the first selective antagonist to prevent the binding of the endogenous ligand orphanin FQ/Nociceptin (OFQ/N) at the orphan opioid-like receptor.