Characteristics of opioid‐maintained clients smoking fentanyl patches: The importance of confirmatory drug analysis illustrated by a case series and mini‐review

: The increase in opioid prescribing in many European countries over the last decade has raised concerns about associated diversion, overdose, and mortality. Fentanyl is one of these synthetic opioids that is typically prescribed as a transdermal patch for pain that requires continuous pain relief and has been the focus of investigation due to reports of overdose and death. We report a case series of 14 drug addiction treatment entrants, who entered treatment in a service located in the region of Southern Denmark from August 2015 to December 2015 for smoking fentanyl patches. Clients presented with difficulties breathing and pains in the lungs. The clients had a history of past opioid use, including heroin. Relapses resulted in treatment disengagement. Immunoassays for fentanyl were used in the service. In some cases, false negative results occurred. Clients' urine samples were subsequently analysed in a collaborating laboratory. Seven clients tested positive for fentanyl. One client was positive for both fentanyl and heroin. Analyses were also positive for other opioids and metabolites in 6 clients, predominantly codeine and oxycodone. Results from confirmatory analysis contributed to clearer insights into clients' drug histories, which facilitated personalised care plans consisting of opioid agonist therapy informed by confirmed drug use. In Denmark, prescription levels of fentanyl are high, which has been accompanied by observations of diversion and smoking in a smaller population. In addition to revision of inappropriate prescribing to reduce diversion, we recommend increased reliance upon confirmatory drug analysis in the addiction treatment sector in Denmark.