Furanylfentanyl: another fentanyl analogue, another hazard for public health

The fentanyls are a family of drugs that have caused hundreds of deaths in Europe and the United States. They first appeared in the United States in the late 1970s; they were sold as heroin to unsuspecting users. Furanylfentanyl is a potent synthetic drug, an analogue of fentanyl that belongs to the above family. It has no proven medical use, but it is abused throughout the world for its opioid-like effects. The drug is mainly manufactured in China and is distributed worldwide. It is used mainly intranasally, but other routes of administration have also been reported. Furanylfentanyl has been involved in many intoxication cases, fatal or not, and many seizures of the drug have been recorded. The aim of this review is to summarize all the available information on furanylfentanyl, concerning its chemistry, synthesis, prevalence, metabolism, pharmacology, and toxicology, as well as its legal status. Analytical methods for the determination of furanylfentanyl in biological specimens are presented. Intoxications and lethal cases published in the scientific literature or reported on the web are also reviewed.