Growth of Nitazenes in the US's Unregulated Drug Supply

"Findings

"Between 2019 and 2024, 7117 nitazene analog reports were submitted to NFLIS, increasing from 43 in 2019 to 1905 in 2024. Counts rose sharply from 2019 to 2021 [count ratio = 7.32; 95% confidence interval (CI) = 2.22–24.20] but did not increase statistically significantly from 2021 to 2024 (count ratio = 1.08; 95% CI = 1.00–1.17). Early detections were predominated by isotonitazene (97.7% of NFLIS nitazene reports in 2019) but later shifted toward metonitazene and protonitazene (29.5% and 30.1%, respectively, in 2024). NPS Discovery identified 361 nitazene-positive biospecimens, increasing from 11 in 2019 to 113 in 2024, with counts increasing by approximately 45% per year (count ratio = 1.45; 95% CI = 1.23–1.71). Nearly all nitazene-positive biospecimens (98.3%) had at least one co-detected substance, most commonly fentanyl (54.6%).

"Conclusions

"Nitazene detections increased sharply across the United States between 2019 and 2024, with shifting patterns in the prevalence of individual nitazenes and extensive polysubstance involvement. These findings highlight the need to strengthen drug testing capacity, expand epidemiological surveillance and implement targeted public health interventions to mitigate harms associated with this emerging class of synthetic opioids."