An outbreak of novel psychoactive substance benzodiazepines in the unregulated drug supply: Preliminary results from a community drug checking program using point-of-care and confirmatory methods.

Background: From mid-2018, an increase in novel psychoactive substance (NPS) benzodiazepines was noted on surveillance of the unregulated drug market around Vancouver, British Columbia, Canada. The rise was concordant with an outbreak of atypical overdoses suspicious for benzodiazepine adulteration of unregulated opioids. This study sought to describe the number and type of NPS benzodiazepines in a sample drawn from a community drug checking program during this period, and to explore accuracy of point-of-care drug checking technologies when compared to confirmatory methods in this sample.

Methods: Point-of-care drug checking data using fentanyl and benzodiazepine test strips as well as Fourier transform infrared spectroscopy were gathered at harm reduction sites in the Vancouver area from October 2018 to January 2020. A convenience subsample underwent confirmatory testing with gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry, or quantitative nuclear magnetic resonance spectroscopy.

Results: Of 159 samples with both point-of-care and confirmatory results, 24 (15.1%) contained at least one NPS benzodiazepine, including etizolam (n = 18), flubromazolam (n = 3), flualprazolam (4), and flubromazepam (n = 1). Of 114 confirmatory samples expected by participants on self-report to contain opioids, 18 (15.8%) contained some NPS benzodiazepine, with 16 (14.0%) containing both an NPS benzodiazepine and an opioid, always fentanyl. False positive and negative rates were 15.5% and 37.5% for test strips, and 3.9% and 91.7% for FTIR, respectively. Combined together, false positive and negative rates of point-of-care methods were 17.8% and 29.2%.

Conclusions: NPS benzodiazepine adulteration in an unregulated drug supply sample reveals new risks compounding ongoing harms associated with the synthetic opioid epidemic. Given substantial false positive and false negative rates noted in our sample for point-of-care detection methods, cautious use of combined point-of-care methods, routinely paired with confirmatory drug checking may aid in early detection and monitoring of unregulated drug markets and inform targeted harm reduction strategies and health policy approaches.