Substance Use
Fentanyl Concentrations in Unregulated Opioids and Blood of Drug Toxicity Decedents: A Time-Series Analysis Samuel Tobias* Samuel Tobias Aaron Shapiro Andrew Tu Sandrine Merette Evan Wood Jane A. Buxton Lianping Ti
Background
Fentanyl toxicity is the leading cause of unnatural death in British Columbia (BC), Canada, largely due to fentanyl’s strong potency and highly variable concentration in community drug samples. In BC, both fentanyl concentration and its variability in community drug samples has been increasing in recent years, but it remains unknown if these same trends present in post-mortem toxicology testing of opioid overdose decedents. This study aims to identify emerging trends and the possible relationship between fentanyl concentrations in community drug samples and fentanyl concentrations in post-mortem blood in the context of an ongoing drug toxicity crisis.
Methods
Data for this study were derived from the BC Coroners Service (agency responsible for investigating all unnatural deaths in BC) and drug checking sites. We analyzed post-mortem blood concentrations of fentanyl from unintentional toxicity decedents occurring in Vancouver, BC alongside fentanyl concentrations of opioid drug checking samples collected in Vancouver. The study period was January 2018 through December 2022. Blood concentrations of fentanyl were compared with monthly median concentrations of drug checking samples over time using a generalized additive model.
Results
Monthly median fentanyl concentrations of opioid samples ranged from 4.5 to 13.7%. A time-series analysis using generalized additive model adjusted for potential confounders indicated a significant non-linear association between drug checking fentanyl concentrations and blood fentanyl concentrations (edf: 3.60, chi-square: 12.63, p = 0.020).
Discussion
Fentanyl concentrations in both the unregulated drug supply and post-mortem blood changed significantly with the two being mutually associated. Further research into complexities of the drug supply, changing substance use patterns, and rates of fentanyl exposure among opioid-naïve individuals may explain this non-linear trend and inform strategies to abate the ongoing loss of life.
