Abuse of fentanyl: An emerging problem to face.

Fentanyl is a potent synthetic opioid used as a narcotic analgesic supplement in general and regional anesthesia as well as in management of persistent, severe chronic pain. Alarming epidemiological and forensic medicine reports, accumulated mainly during the last two decades, point to a growing increase in illicit use of fentanyl, mainly in North America and Europe. Toxicological data indicates that fentanyl use is inextricably linked with polydrug use. There are two main sources of fentanyl on the "recreational" drug market. First, the most common, combines illicitly manufactured fentanyl from clandestine sources. The drug is often mixed up with heroin ("fake heroin") to increase its potency at a little cost, or included in cocaine products. It can also be mixed into and sold as oxycodone-, hydrocodone- or alprazolam-containing tablets. The other way to gain fentanyl is through the diversion of fentanyl-containing medicines, especially transdermal patches (FTPs). Fentanyl extracted from FTP can be administered intravenously, insufflated or inhaled after volatilization. The drug can also be delivered by oral or transmucosal application of the whole patch, or by rectal insertion. The most common overdose symptoms are coma, lethargy, respiratory depression and arrest. Although naloxone, an opioid receptor antagonist, is the standard drug for fentanyl overdose rescue, attempts to revive patients with naloxone could be unsuccessful, due to the rapid onset of fentanyl's action. As the fentanyl problem is constantly growing, there is an urgent need for new, effective harm-reduction strategies and technologies, as well as overdose maintenance.