Furanylfentanyl Powder now, 3-m-furanylfentanyl is an very strong opioid which is structurally related to the highly potent opioid analgesic fentanyl. IUPAC names of 3-m-furanylfentanyl is FU-F 2 and furanoylfentanyl, N-Phenyl-N-[1-(2-phenylethyl)piperidin-4-yl]-furan-2-carboxamide, has absolute molar mass of 374.475 grams and empirical formula C24H26N2O2. It has an ED50 value in mice of 0.02 mg/ kg. This gives furanylfentanyl a strength of 20% of fentanyl which is one of the strongest opioid painkiller.Furanylfentanyl Powder has been increasing in practice in the US within the last decade. It is a very strong intoxicate that has been related to thousands of deaths. Overdose of fentanyl is very problematic particularly when it is integrated as an mixed in street heroin in order to increase its strength.