cck-4 cck-4 cholecystokinin tetrapeptide (cck-4, tetragastrin, trp-met-asp-phe-nh2) is a peptide fragment derived from the larger peptide hormone cholecystokinin. unlike cholecystokin which has a variety of roles in the gastrointestinal system as well as central nervous system effects, cck-4 acts primarily in the brain as an anxiogenic, although it does retain some gi effects, but not as much as cck-8 or the full length polypeptide cck-58. cck-4clinical dataother namestetragastrin; cholecystokinin tetrapeptideroutes ofadministrationivpharmacokinetic databioavailability100%metabolismplasma protease enzymeselimination half-life13 minutesexcretionn/aidentifiers iupac name (3s)-3--3--3-(methylsulfanyl)propyl]carbamoyl}propanoic acid cas number1947-37-1 ypubchem cid446569chemspider393888 nunii0ol293av80chebichebi:137728chemical and physical dataformulac29h35n5o7smolar mass597.69 g·mol−13d model (jsmol)interactive image smiles cscc(c(=o)n(cc(=o)o)c(=o)n(cc1ccccc1)c(=o)n)nc(=o)(cc2cc3c2cccc3)n inchi inchi=1s/c29h36n6o6s/c1-42-12-11-22(33-27(39)20(30)14-18-16-32-21-10-6-5-9-19(18)21)28(40)35-24(15-25(36)37)29(41)34-23(26(31)38)13-17-7-3-2-4-8-17/h2-10,16,20,22-24,32h,11-15,30h2,1h3,(h2,31,38)(h,33,39)(h,34,41)(h,35,40)(h,36,37)/t20-,22-,23-,24-/m0/s1 nkey:rgylyuzoghtbrf-bihrqfpbsa-n n ny (what is this?) (verify) cck-4 reliably causes severe anxiety symptoms when administered to humans in a dose of as little as 50 μg, and is commonly used in scientific research to induce panic attacks for the purpose of testing new anxiolytic drugs. since it is a peptide, cck-4 must be administered by injection, and is rapidly broken down once inside the body so has only a short duration of action, although numerous synthetic analogues with modified properties are known.