Introduction: Acetylfentanyl, an N-acetyl derivative of fentanyl, has recently been reported in a number of fatalities in different areas in the United States. Initially, 10 deaths were reported in Rhode Island in March and April of 2013. Later deaths were also reported in Pennsylvania, Louisiana (Jefferson Parish) and North Carolina. Pharmacologically, acetylfentanyl has been shown in animals to bind to mu-opioid receptors similarly to fentanyl although the potency of the acetylfentanyl appears to be lower in rat studies. Acetylfentanyl does cross-react with certain fentanyl immunoassay kits on the market. However, in our laboratory screening for acetylfentanyl is accomplished using accurate mass screening (LC-TOF/MS) followed by confirmation by LC-MS/MS. In this presentation we report the findings in 29 deaths related to acetylfentanyl between July 2013 and September 2014. Additionally, we will report on a sudden increase in deaths due to heroin being substituted with our tainted with fentanyl. 

Materials and Methods: A total of 29 cases with detectable concentrations of acetylfentanyl in postmortem blood were identified during the study period. Eighteen (18) cases were submitted for full postmortem toxicology screening and 11 cases were submitted specifically for directed analysis. All testing was performed in whole blood, but the source varied (e.g. peripheral, cardiac etc.). One case was also had liver tissue tested. 

Results: The average acetylfentanyl concentration for the 29 cases was 393 ng/mL (range: 0.25 – 3800 ng/mL). Only four cases had acetylfentanyl concentrations below 1 ng/mL but 20 cases exceeded 100 ng/mL. A single case in which both blood and liver acetylfentanyl were quantified had concentrations of 150 ng/mL and 1900 ng/g, respectively. All decedents were male (except one female and one not provided) and the average age was 32 years (N=23, range: 17-54 years). Three cases were also positive for fentanyl, one at a high (22 ng/mL) and two at low (< 1 ng/mL) concentrations. These cases will be discussed alongside a recent doubling, from 15 to 30, of fentanyl-related deaths associated with heroin use (as identified by the presence of 6-acetylmorphine) in the third quarter of 2014 and almost then triple that number to 88 in the fourth quarter of 2014 on samples tested at NMS labs. 

Conclusions: There were 29 acetylfentanyl-related deaths for the 15 months beginning July 2013. Cases were identified in many geographical regions of the United States. The concentrations of acetylfentanyl were notably higher compared to the concentrations of fentanyl in fentanyl-related deaths, however no clinical studies have been performed with humans for this drug. At the same time, there has been a sudden increase in the number of combined heroin and fentanyl related deaths due to the addition of, or substitution with, fentanyl to heroin. 

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