parafluorofentanyl parafluorofentanyl parafluorofentanyl (4-fluorofentanyl, pff) is an opioid analgesic analogue of fentanyl developed by janssen pharmaceutica in the 1960s. parafluorofentanylclinical dataother names4-fluorofentanyl; para-fluorofentanyl; pffatc codenonelegal statuslegal status ca: schedule i de: anlage i (authorized scientific use only) uk: class a us: schedule i identifiers iupac name n-(4-fluorophenyl)-n-propanamide cas number90736-23-5 ypubchem cid62300chemspider56096 yuniii45r05qm0zchebichebi:61074 ycomptox dashboard (epa)dtxsid0048929 chemical and physical dataformulac22h27fn2omolar mass354.469 g·mol−13d model (jsmol)interactive image smiles fc1ccc(cc1)n(c(=o)cc)c3ccn(ccc2ccccc2)cc3 inchi inchi=1s/c22h27fn2o/c1-2-22(26)25(20-10-8-19(23)9-11-20)21-13-16-24(17-14-21)15-12-18-6-4-3-5-7-18/h3-11,21h,2,12-17h2,1h3 ykey:kxubavlijftasz-uhfffaoysa-n y ny (what is this?) (verify) 4-fluorofentanyl was sold briefly on the us black market in the early 1980s, before the introduction of the federal analog act which for the first time attempted to control entire families of drugs based on their structural similarity rather than scheduling each drug individually as they appeared. 4-fluorofentanyl is made by the same synthetic route as fentanyl, but by substituting para-fluoroaniline for aniline in the synthesis. side effects of fentanyl analogs are similar to those of fentanyl itself, which include itching, nausea and potentially serious respiratory depression, which can be life-threatening. fentanyl analogs have killed thousands of people throughout europe and the former soviet republics since the most recent resurgence in use began in estonia in the early 2000s, and novel derivatives continue to appear. in 2020, the drug enforcement agency warned about the increasing prevalence of parafluorofentanyl in arizona.