Fentanyl-related deaths in Ontario, Canada: toxicological findings and circumstances of death in 4395 cases (2020–22)
Open accessAbstract
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.
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Isotonitazene produces the active metabolite N-desethyl isotonitazene, which is more potent than its parent compound.
“According to vandeputte et al. [7], isotonitazene produces the active metabolite N-desethyl isotonitazene, which is more potent than its parent compound [20].”
From Nitazenes: review of comparative pharmacology and antagonist action (2025) · cites this paper as [20]
The Results section reports isotonitazene among substances detected with fentanyl (n = 30), but does not discuss its metabolism or potency. Searches for N-desethyl isotonitazene and for metabolite potency found no passage addressing the claim; page numbers were not available in our copy. (LLM, conf=0.75)
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Nitazenes: review of comparative pharmacology and antagonist action
Stangeland, M., Dale, O., & Skulberg, A. K. (2025) · Clinical Toxicology · doi:10.1080/15563650.2025.2504133 · Cited by 34 · see citing works
“Post-mortem fentanyl concentrations were recently reported in 824 cases from Canada (median: 16 µg/L; range: 1.3–200 µg/L) [21].”
Influential
- Authors
- Adamo, A., Marshall, K., & Woodall, K. L.
- Affiliations
- University of Toronto (CA)
- Corresponding author
- Woodall, Karen L
- ORCID
- Woodall, Karen L
- Venue
- Journal of Analytical Toxicology
- Publisher
- Oxford University Press (OUP)
- Published
- 2024-07-05
- Volume
- 48
- Issue
- 8
- Pages
- 598-605
- ISSN
- 0146-4760 (ISSN-L)
- 1945-2403
- PMC
- PMC11515131
- OpenAlex
- W4400378256
- Cited by
- 8
- References
- 0
- Citations by year
- 2026: 3 · 2025: 4 · 2023: 1
- FWCI
- 1.67
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- Journal of Analytical Toxicology (publishedVersion, cc-by-nc)
- PubMed Central (publishedVersion, cc-by-nc)
- PubMed (publishedVersion)
- Topics
- Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Toxicology › Forensic Toxicology and Drug Analysis
- Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Opioid Use Disorder Treatment
- Health Sciences › Medicine › Emergency Medicine › Poisoning and overdose treatments
- Keywords
- fentanyl, toxicological findings, plasma drug concentration, cocaine, methamphetamine, stimulants, forensic toxicology, Ontario, drug use trends
- MeSH terms
- Adolescent, Adult, Aged, Aged, 80 and over, Analgesics, Opioid, Cause of Death, Child, Child, Preschool, Chromatography, Liquid, Female, Fentanyl, Humans, Infant, Infant, Newborn, Male, Middle Aged, Ontario, Retrospective Studies, Substance Abuse Detection, Forensic Toxicology, Tandem Mass Spectrometry, Young Adult, Drug Overdose
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