The Detection of Novel Nitazene‐Class Opioids in Unregulated Drug Markets in Canada

INTRODUCTION: Nitazenes, a highly potent class of synthetic opioids, have emerged in Canadian unregulated drug markets. We report on their presence and composition, along with overdose trends. METHODS: Samples were obtained from January 2019 to July 2024 from two drug checking services (Toronto's Drug Checking Service (TDCS) and drug checking partners affiliated with the British Columbia Centre on Substance Use (BCCSU)) and national police seizure data from Health Canada's Drug Analysis Service (HC-DAS). Overdose data were retrieved from the Office of the Chief Coroner for Ontario from January 2019 to December 2022 and included deaths in which a nitazene was present. We conducted Cochran-Armitage test and logistic regression trend analyses to assess trends over time. RESULTS: Of 668,486 samples, 4074 (0.61%) contained nitazenes: 532 from drug checking services (489 (0.07%) from TDCS; 43 (0.01%) from BCCSU) and 3542 (0.53%) from police seizures (HC-DAS). Twelve unique nitazenes were detected. Common co-occurring drugs included caffeine, benzodiazepine-related drugs and fentanyl and fentanyl-related drugs. Nitazenes were expected in 3 (< 1%) of 532 drug checking samples. Of 14,103 samples from TDCS, 886 (6.28%) were associated with an overdose, among which 76 (8.58%) contained nitazenes. Of 8719 opioid deaths in Ontario and 1803 in Toronto, nitazenes were present in 79 (0.91%) and 33 (1.83%), respectively. Significant trends (p < 0.001) in nitazene detections and overdoses in Toronto, as well as nitazene detections across Canada, were observed, increasing prior to and peaking in January-March 2022, followed by reductions. DISCUSSION AND CONCLUSIONS: The presence of nitazenes in Canada requires enhanced overdose prevention responses and drug market monitoring.