EMCDDA - Europol Joint Report 2017:
Tetrahydrofuranylfentanyl has been available in the European Union since at least September 2016. It has been detected in one Member State where it has been seized as a liquid and a powder. The detected quantities are relatively small; however, they should be seen within the context of the high potency that is typical of the fentanils.

The most serious acute health risk posed by tetrahydrofuranylfentanyl is likely to be respiratory depression, which in overdose can be life-threatening. The antidote naloxone should reverse acute poisoning.

Fourteen deaths with confirmed exposure to tetrahydrofuranylfentanyl have been reported by one Member State. In at least 12 of the deaths, tetrahydrofuranylfentanyl was the cause of death or contributed to the death.

Tetrahydrofuranylfentanyl is sold and used as a substitute for illicit opioids and prescription opioids.

Similar to other fentanils, serious concerns exist that the substance could be supplied surreptitiously to a range of drug users.

THF-F Joint Reports (PDF 13 pages):
https://www.emcdda.europa.eu/system/files/publications/5487/2017.4968_TDAS17008ENN_PDFWEB.pdf

World Health Organization 2017:
Unclassified and potent synthetic analogs of fentanyl continue to emerge on the illicit market, one of the latest agents appearing is tetrahydrofuranylfentanyl (THF-F). Tetrahydrofuranylfentanyl belongs to the same class of opioids as internationally controlled fentanyl and its derivatives. Tetrahydrofuranylfentanyl seems to have arrived on the scene shortly after the scheduling of other fentanyl derivativesin 2016 and is available for purchase as powders, tablets, or nasal spray solutions.

The most serious acute health risk posed by tetrahydrofuranylfentanyl appears to be respiratory depression and death; reported overdose with tetrahydrofuranyl fentanyl can be reversed with naloxone. The population likely to abuse tetrahydrofuranyl fentanyl, either knowingly or unknowingly, intersects with the population using heroin, fentanyl, prescription opioid analgesics, and other fentanyl-related substances as evidenced by the routes of drug administration, the drug use history,and the paraphernalia found at fatal overdose cases.

Tetrahydrofuranyl fentanyl is one of the latest fentanyl derivatives to be sold and used in a similar manner as other licit and illicit opioids. At the current time, there is evidence that tetrahydrofuranyl fentanyl poses similar public health risks as the fentanyl derivatives that preceded it.

Tetrahydrofuranylfentanyl (THF-F) Critical Review Report: (2017) (PDF 19 pages):
https://www.who.int/medicines/access/controlled-substances/CriticalReview_THFF.pdf?ua=1

Tetrahydrofuran Fentanyl (Hydrochloride) Safety Data Sheet (PDF 5 pages):
https://www.caymanchem.com/msdss/20859m.pdf

Tetrahydrofuran Fentanyl Monograph (PDF 5 pages):
https://www.swgdrug.org/Monographs/Tetrahydrofuran%20fentanyl.pdf

• An opioid analgesic
• An analog of fentanyl
• Has been sold online as a designer drug
• First appeared in Europe in late 2016

Side effects of fentanyl analogs are similar to those of fentanyl itself