Flualprazolam and flubromazolam: Blood concentrations and prevalence of two novel psychoactive substances in forensic case work in Ontario, Canada.

Flualprazolam and flubromazolam are synthetic benzodiazepines that have not been approved for use in humans. They are categorized as novel psychoactive substances (NPS), and have been increasingly encountered in forensic case work. This report examines information from cases analyzed for flualprazolam and flubromazolam between July 1 and December 31, 2021 to identify the prevalence, trends and demographic data associated with these novel drugs in Ontario, Canada. Flualprazolam was identified in blood, serum or liver in 395 death investigations, 108 impaired driving and five sexual assault cases. Among all case types, blood concentrations were determined in 123 individuals aged 19-66 years. In impaired driving and sexual assault cases, flualprazolam blood concentrations ranged from <1.3 to 227 ng/mL (median 11.0 ng/mL), whereas a range of 3-59 ng/mL (median 6.8 ng/mL) was reported in death investigations. Flubromazolam was identified in blood, serum or liver in 137 death investigations, 55 impaired driving and one sexual assault case. Blood concentrations ranged from <1.3 to 323 ng/mL in 65 individuals, aged 14-61 years. In impaired driving and sexual assault cases, flubromazolam blood concentrations ranged from <1.3 to 323 ng/mL (median 7.7 ng/mL), which overlapped with the range of 2-220 ng/mL (median 8.0 ng/mL) reported in death investigations. Other drugs were frequently detected with flualprazolam and flubromazolam with opioids identified in more than 89% of positive flualprazolam and flubromazolam cases. These results demonstrated the prevalence of flualprazolam and flubromazolam in Ontario, Canada. Trends showed that over the 6-month period, as the number of flubromazolam cases decreased, the incidences of flualprazolam increased. An overlap in concentrations of these drugs was observed in both death investigations and cases involving living individuals. These data provide valuable information for the scientific community regarding the use of these drugs in antemortem and postmortem casework.