Trends in synthetic cathinone detection in seized drug samples submitted to the U.S. DEA's National Forensic Laboratory Information System, 2010-2024.

Synthetic cathinones are a chemically diverse class of novel stimulants that continue to emerge in the United States and globally. Trends in overall and specific synthetic cathinone availability in the United States (as indicated by seizures) remain poorly characterized. We analyzed annual counts of reports submitted from 2010 to 2024 to the U.S. Drug Enforcement Administration's National Forensic Laboratory Information System (NFLIS). We grouped reports into chemical subclasses of beta-keto methylenedioxyamphetamines ("-ylones"), pyrrolidinophenones ("pyrros"), and beta-keto amphetamines ("-drones"). Temporal trends in total reports and subclasses were modeled using negative binomial regression spline models. To further contextualize subclass trends, we descriptively examined the contribution of individual synthetic cathinones over time. Between 2010 and 2024, 178 892 synthetic cathinone reports were submitted to NFLIS, of which 73.3% were classified as -ylones, 19.9% as pyrros, 5.2% as -drones, and 1.6% as other. 68.7% of total reports were from the South, with 33.5% from Florida. Nationally, total reports increased sharply in 2010-2013, declined mid-period, rose again from 2019 to 2020, and then stabilized. Additional regional and temporal heterogeneity was noted across subclasses. We identified patterns of rapid emergence and replacement of individual compounds within subclasses, particularly within the -ylone subclass. Overall, we found substantial temporal, regional, and subclass-specific variation in synthetic cathinone reports to NFLIS from 2010 to 2024, largely driven by reports from the South and from successive cycles of replacement of -ylones. These findings emphasize the need to strengthen forensic and epidemiological surveillance of the evolving synthetic cathinone landscape in the United States.