The utility of visual appearance in predicting the composition of street opioids.

Background: With the emergence of unregulated fentanyl, people who use unregulated opioids are increasingly relying on appearance in an effort to ascertain the presence of fentanyl and level of drug potency. However, the utility of visual inspection to identify drug composition in the fentanyl era has not been assessed. Methods: We assessed client expectation, appearance, and composition of street drug samples being presented for drug checking. Results of a visual screening test were compared to fentanyl immunoassay strip testing. We calculated sensitivity, specificity and likelihood ratios (LR) to assess the accuracy of the common assumption that samples with a "pebbles" appearance contain fentanyl. Results: In total, of the 2502 unregulated opioid samples tested, 1820 (73.5%) appeared as "pebbles", of which 1729 (95.0%) tested positive for fentanyl for a sensitivity of 75.9% (95% Confidence Interval [CI]: 74.2-77.6) and specificity of 59.4% (95%CI: 57.5-61.3). Although, the odds of samples containing fentanyl was 4.60 (95%CI: 3.47-6.11) times higher among pebbles samples compared to non-pebble samples, the positive LR for pebbles to contain fentanyl was only 1.87 (CI: 1.59-2.19). The negative LR was more useful at 0.41 (95% CI: 0.36-0.46). Conclusions: A positive screening test for pebbles is not strongly enough associated to be used as a proxy for detecting fentanyl. While the absence of the appearance of pebbles does somewhat reduce the likelihood of fentanyl being present in a given sample, the high prevalence of fentanyl and fentanyl analogues in the drug supply and the risks of consumption are such that public health providers should routinely advise people who use unregulated opioids against solely relying on visual characteristics of drugs as a harm reduction strategy.

Take-home drug checking as a novel harm reduction strategy in British Columbia, Canada.

BACKGROUND: Drug checking is a harm reduction strategy used to identify components of illicitly obtained drugs, including adulterants, to prevent overdose. This study evaluated the distribution of take-home fentanyl test strips to people who use drugs (PWUD) in British Columbia, Canada. The primary aim was to assess if the detection of fentanyl in opioid samples was concordant between a take-home model and testing by trained drug checking staff. METHODS: Take-home fentanyl test strips were distributed at ten sites providing drug checking services from April to July 2019. The fentanyl positivity of the aggregate take-home and on-site drug checking groups were compared by class of substance tested. An administered survey assessed acceptability and behaviour change. RESULTS: 1680 take-home results were obtained from 218 unique participants; 68% of samples (n=1142) were identified as opioids and 23% (n=382) were stimulant samples. During this period, 852 samples were tested using on-site drug checking. The fentanyl positivity of opioid samples was 90.0% for take-home samples and 89.1% for on-site samples (Difference 0.8% (95% CI -2.3% to 3.9%)). These results were not affected by previous experience with test strips. Fentanyl positivity of stimulants in the take-home group was higher than on-site (24.7% vs. 3.2%), but the study was underpowered to conduct statistical analysis on this sub-group. When fentanyl was detected, 27% of individuals reported behaviour change that was considered safer/positive. Greater than 95% of participants stated they would use fentanyl test strips again. CONCLUSIONS: Take-home fentanyl test strips used by PWUD on opioid samples can provide similar results to formal drug checking services and are a viable addition to existing overdose prevention strategies. Use of this strategy for detection of fentanyl in stimulant samples requires further evaluation. This intervention was well accepted and in some participants was associated with positive behaviour change.

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.