The rise and rise of fentanyl in postmortem casework

Reinforcing effects of fentanyl analogs found in illicit drug markets

RATIONALE

The potent synthetic opioid fentanyl, and its analogs, continue to drive opioid-related overdoses. Although the pharmacology of fentanyl is well characterized, there is little information about the reinforcing effects of clandestine fentanyl analogs (FAs).

OBJECTIVES

Here, we compared the effects of fentanyl and the FAs acetylfentanyl, butyrylfentanyl, and cyclopropylfentanyl on drug self-administration in male and female rats. These FAs feature chemical modifications at the carbonyl moiety of the fentanyl scaffold.

METHODS

Sprague-Dawley rats fitted with intravenous jugular catheters were placed in chambers containing two nose poke holes. Active nose poke responses resulted in drug delivery (0.2 mL) over 2 s on a fixed-ratio 1 schedule, followed by a 20 s timeout. Acquisition doses were 0.01 mg/kg/inj for fentanyl and cyclopropylfentanyl, and 0.03 mg/kg/inj for acetylfentanyl and butyrylfentanyl. After 10 days of acquisition, dose-effect testing was carried out, followed by 10 days of saline extinction.

RESULTS

Self-administration of fentanyl and FAs was acquired by both male and female rats, with no sex differences in acquisition rate. Fentanyl and FAs showed partial inverted-U dose-effect functions; cyclopropylfentanyl and fentanyl had similar potency, while acetylfentanyl and butyrylfentanyl were less potent. Maximal response rates were similar across drugs, with fentanyl and cyclopropylfentanyl showing maximum responding at 0.001 mg/kg/inj, acetylfentanyl at 0.01 mg/kg/inj, and butyrylfentanyl at 0.003 mg/kg/inj. No sex differences were detected for drug potency, efficacy, or rates of extinction.

CONCLUSIONS

Our work provides new evidence that FAs display significant abuse liability in male and female rats, which suggests the potential for compulsive use in humans.

Fentanyl-related deaths in Ontario, Canada: toxicological findings and circumstances of death in 4395 cases (2020-22)

Over the last 20 years, there has been a significant increase in fentanyl-related deaths in Ontario, Canada. This report examines toxicological findings in a series of death investigations in which fentanyl was quantitated to identify the prevalence, trends, and demographic data associated with fentanyl in Ontario, Canada, and to highlight the changes in these trends since fentanyl began appearing in casework in Ontario in the early 2000s. A retrospective study of all cases in which fentanyl was quantitated in blood, using liquid chromatography (LC)-tandem mass spectrometry (MS-MS), was conducted for the time period between 1 January 2020 and 31 December 2022. A total of 4395 cases were included; 77% of the decedents were male, and 23% was female with ages ranging from 0 to 95 years. The most frequently classified cause of death was mixed drug toxicity (69%) followed by fentanyl intoxication at 19%. Less than 10% of cases where fentanyl was quantitated were classified as nondrug-related deaths. Fentanyl concentrations in all cases ranged from 1.3 to >2000 ng/mL. Other drugs were frequently detected with fentanyl. In mixed drug toxicity cases, stimulants were the most frequently encountered class of drugs: cocaine was identified in 51.8%, and methamphetamine was observed in 43.0% of cases. Detailed reports for select cases were included to provide additional insight into the different case types and to show the difficulty in interpreting blood concentrations without additional detailed case histories. This study provides valuable information for the scientific and medical community regarding the continued use of fentanyl and how patterns of fentanyl use have evolved since it began to appear in forensic casework.

Drug Trends in the Teenage Postmortem Population From 2017 to 2021

ABSTRACT

The teenage population is highly vulnerable to drug exposure, use, and misuse due to the physical and emotional development that occurs at those ages. Social influences, like the isolation experienced during the COVID-19 pandemic and social media, can exacerbate this vulnerability. To better understand the potential impact of these influences on teenage drug use, postmortem results reported by a large reference laboratory from 2017 to 2021 corresponding to the teenage population were evaluated for various drugs of misuse. These data revealed a marked increase (385%) in reported fentanyl cases and a 13% increase in positivity rate. Methamphetamine- and cocaine-positive cases also increased 126% and 54%, with a net percent positivity of +0.6% and -0.5%, respectively. Conversely, heroin showed a consistent decline in reported cases (67%) and a net decrease of 1.0% in positivity rate. In addition to commonly misused drugs, trends for other substances that are prevalent in social media and therefore may disproportionally impact teens, MDMA/MDA, mitragynine, and diphenhydramine, were also assessed. A discussion of drug-related social media trends is presented to provide additional context for the data and trends reported herein, ultimately creating a framework through which social influences on teenage drug use can be better understood.

A quantitative LC-MS/MS analysis of Xylazine, p-Fluorofentanyl, Fentanyl and Fentanyl-Related compounds in postmortem blood

The purpose of this study was to develop and validate a method to quantitate the veterinary sedative xylazine as well as 4-anilino-N-phenethylpiperidine (4-ANPP), acetyl fentanyl, fentanyl, norfentanyl, and p-fluorofentanyl in blood utilizing liquid chromatography tandem mass spectrometry. This method also qualitatively monitors for the presence of o-fluorofentanyl and m-fluorofentanyl isomers. UCT Clean Screen® DAU extraction columns were utilized to isolate the analytes in postmortem blood samples. The extracts were eluted, evaporated, reconstituted, and then analyzed using a Waters Acquity™ UPLC coupled a triple quadrupole mass spectrometer. The lower limit of quantitation was determined to be 0.1 ng/mL for all analytes, except for xylazine (0.2 ng/mL). The upper limit of quantitation for all analytes was 100 ng/mL. No interferences from matrix, internal standard, or common drug analytes were observed. Bias (-13.1-4.6 %) and precision (-13.14-10.3 %) fell within the acceptable ± 20 % criteria range. Dilution integrity at x2, x10, and x100 was evaluated and all results were within ± 20 % of the target concentration. Processed extract stability was evaluated after 72 h and all results were within ± 20 % of the analyte initial concentration. Matrix effects were the most prominent with xylazine, but deemed acceptable as the deuterated internal standard also observed comparable enhancement. Analysis of 89 postmortem blood samples by this method resulted in positive results for fentanyl (0.27-66 ng/mL, n = 82), xylazine (0.24-958 ng/mL, n = 21), 4-ANPP (0.10-38 ng/mL, n = 72), acetyl fentanyl (0.18-1.5 ng/mL, n = 3), p-fluorofentanyl (0.11-33 ng/mL, n = 30), and norfentanyl (0.10-98 ng/mL, n = 73).

Xylazine Poisoning in Clinical and Forensic Practice: Analysis Method, Characteristics, Mechanism and Future Challenges

Xylazine abuse is emerging globally, while the identification of xylazine lethal cases poses a great challenge in clinical and forensic practice. The non-specific symptoms delay the diagnosis and treatment of xylazine poisoning, the pathological changes and lethal concentration of xylazine in body fluid and organs of fatal xylazine poisoning cases are seldom reported and the other toxins detected in such cases complicate the role of xylazine in the cause of death. Therefore, we carefully reviewed related updated information on xylazine, summarized the knowledge from clinical and forensic perspectives and can thus provide a reference in such cases and throw light on further study in the field of xylazine poisoning.