4-methylphenethylacetylfentanyl 4-methylphenethylacetylfentanyl 4-methylphenethylacetylfentanyl (acetylfentanyl 4-methylphenethyl analog) is an opioid analgesic that is an analog (and structural isomer) of fentanyl and has been sold as a designer drug. 4-methylphenethylacetylfentanyllegal statuslegal status ca: schedule i uk: class a us: schedule i identifiers iupac name n--4-piperidinyl]-n-phenylacetamide cas number1071703-95-1 ypubchem cid91736720chemspider29752849uniitay1hu5yo4chemical and physical dataformulac22h28n2omolar mass336.479 g·mol−13d model (jsmol)interactive image smiles cc1ccc(cc1)ccn2ccc(cc2)n(c(=o)c)c3ccccc3 inchi inchi=1s/c22h28n2o/c1-18-8-10-20(11-9-18)12-15-23-16-13-22(14-17-23)24(19(2)25)21-6-4-3-5-7-21/h3-11,22h,12-17h2,1-2h3key:bbmrihxvaunkev-uhfffaoysa-n side effects 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 hundreds 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. a new wave of fentanyl analogues and associated deaths began in around 2014 in the us, and have continued to grow in prevalence; especially since 2016 these drugs have been responsible for hundreds of overdose deaths every week. legal status in the united states, fentanyl-related substances are schedule i controlled substances. 4-methylphenethylacetylfentanyl was explicitly banned in arkansas in 2018.