Five new antagonists of Substance P were designed and synthesized towa
rd increasing potency and safety. One of them was more effective than
Spantide II, which was the basis for the design. It was named Spantide
III and has the structure: cLys,Pro,Pal,Pro,D-Cl2Phe,Asn,D-Trp,Phe,D-
Pal,Leu, NleNH2.