3-methylbutyrfentanyl 3-methylbutyrfentanyl 3-methylbutyrfentanyl (3-mbf) is an opioid analgesic that is an analog of butyrfentanyl. 3-methylbutyrfentanyllegal statuslegal status ca: schedule i de: npsg (industrial and scientific use only) uk: class a us: schedule i identifiers iupac name n--n-phenylbutanamide cas number97605-09-9pubchem cid86130531chemspider57434313unii875l53t89nchemical and physical dataformulac24h32n2omolar mass364.533 g·mol−13d model (jsmol)interactive image smiles cccc(=o)n(c1ccccc1)c2ccn(cc2c)ccc3ccccc3 inchi inchi=1s/c24h32n2o/c1-3-10-24(27)26(22-13-8-5-9-14-22)23-16-18-25(19-20(23)2)17-15-21-11-6-4-7-12-21/h4-9,11-14,20,23h,3,10,15-19h2,1-2key:zpaosklofzwbls-uhfffaoysa-n 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.