What is furanyl fentanyl? Well, it's never been sold as a prescription pharmaceutical. Unless you've been buying opioids through non-medical channels, you are unlikely to have encountered it. Furanyl fentanyl is a chemical relative of the medically useful drug, fentanyl, and is the latest of fentanyl analogues that clandestine chemists have been making to circumvent international controlled substances laws. Fentanyl analogues have been re-emerging in the recreational drug trade since an insurgence in the mid-1980s. While fentanyl has a peak effect similar to other opioids, it can be achieved with doses 50 to 100 times less than morphine. Therefore, fentanyl and its chemical relatives have been more easily transported, and trafficking in those without controlled substances-designation has been largely legal.

The fentanyl class of opioids are generally more potent than any other group of naturally occurring or synthetic opioids. What this means to non-pharmaceutical users is that very small differences in measurements can lead to catastrophic health effects. Street drugs don't come with a certificate of analysis as to their content, so small doping of heroin or cocaine with fentanyl or a chemical relative can be potentially lethal to the user.

World Health Organization 2017:
Furanyl Fentanyl is a new designer opioid drug. It is a derivative of fentanyl with two distinctive characteristics:

1. Higher liposolubility that allows its rapid absorption into general circulation
2. It binds to mu-opioid receptors with significant higher affinity than morphine

These characteristics give furanyl fentanyl a highly risky pharmacological profile. In the last several years there has been an increase in deaths due to the use of this designer opioid. Furthermore, it has been reported that it might be present in cocaine crack and other illicit drugs sold on the black market.

World Health Organization Furanyl Fentanyl Review Report (PDF 16 pages):
https://www.who.int/medicines/access/controlled-substances/Critical_Review_FuranylFentanyl.pdf

Furanylfentanyl

Duration: An extremely potent opioid analgesic and analogue of fentanyl. Concrete information is difficult to obtain about even basic properties like active dose, though it is believed to be slightly less potent and shorter in duration than butyrfentanyl. Exercise extreme caution. Will cause respiratory depression in overdose. NOTE: Very potent opioid, be very careful while dosing.
Route	Onset	Duration	After Effects
Tripsit Factsheets
Furanylfentanyl Basic Information: http://drugs.tripsit.me/furanylfentanyl
All ROAs:	1-10 minutes	1-3 hours	1-3 hours

EMCDDA - Europol Joint Report 2017:
Furanylfentanyl has been available in the European Union since at least June 2015 and has been detected in 16 Member States and Norway. In most cases it has been seized as a powder, but other forms such as liquids, tablets, and herbal material have also been detected. The detected quantities are relatively small; however, they should be seen within the context of the high potency of the substance.

Nineteen deaths associated with furanylfentanyl have been reported by 4 Member States and Norway, all of which were analytically confirmed. 90% of the deaths occurred during 2016. In at least 9 of the deaths furanylfentanyl was the cause of death or contributed to the death.

Information on the use of furanylfentanyl in Europe is limited. It appears that furanylfentanyl is used as a drug in its own right. However, serious concerns exist that the substance could be supplied surreptitiously to a range of drug users, including those who inject opioids

European Monitoring Centre for Drugs and Drug Addtiction Furanylfentanyl (PDF 49 pages):
http://www.emcdda.europa.eu/system/files/publications/6712/20176480_TDAK17002ENN_PDF.pdf Furanylfentanyl Joint Reports (PDF 21 pages):
https://www.emcdda.europa.eu/system/files/publications/4682/JOINT_REPORT_furanylfentanyl_web.pdf

Furanylfentanyl:

• An opioid analgesic
• An analog of fentanyl
• Approximately one fifth as potent as fentanyl
• Has been sold as a designer drug
• 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.