frakefamide frakefamide frakefamide (inn) is a synthetic, fluorinated linear tetrapeptide with the amino acid sequence tyr-d-ala-(p-f)phe-phe-nh2 which acts as a peripherally-specific, selective μ-opioid receptor agonist. despite its inability to penetrate the blood-brain-barrier and enter the central nervous system, frakefamide has potent analgesic effects and, unlike centrally-acting opioids like morphine, does not produce respiratory depression, indicating that its antinociceptive effects are mediated by peripheral μ-opioid receptors. it was under development for the treatment of pain by astrazeneca and shire but was shelved after phase ii clinical trials. frakefamideclinical dataother namesl-tyrosyl-d-alanyl-4-fluoro-l-phenylalanyl-l-phenylalaninamideatc codenoneidentifiers iupac name (2s)-2-propanamido]-n--3-(4-fluorophenyl)propanamide cas number188196-22-7pubchem cid9829352chemspider8005088uniidm32b4gu70chemical and physical dataformulac30h34fn5o5molar mass563.630 g·mol−13d model (jsmol)interactive image smiles c(c(=o)n(cc1=cc=c(c=c1)f)c(=o)n(cc2=cc=cc=c2)c(=o)n)nc(=o)(cc3=cc=c(c=c3)o)n inchi inchi=1s/c30h34fn5o5/c1-18(34-29(40)24(32)15-20-9-13-23(37)14-10-20)28(39)36-26(17-21-7-11-22(31)12-8-21)30(41)35-25(27(33)38)16-19-5-3-2-4-6-19/h2-14,18,24-26,37h,15-17,32h2,1h3,(h2,33,38)(h,34,40)(h,35,41)(h,36,39)/t18-,24+,25+,26+/m1/s1key:gtphqorjkfjirb-jtqlptlwsa-n