Determination of nitazenes in postmortem casework and their prevalence in the State of Maryland.

The 2-benzylbenzimidazole class of synthetic opioids-more commonly referred to as the "nitazenes"-are the latest of several classes of novel psychoactive substances to predominate the illicit drug market. Following the class-wide scheduling of fentanyl analogs and fentanyl-related substances in 2018, forensic toxicology laboratories in the United States began to see a proliferation of these novel synthetic opioids in casework initially stemming from the emergence of isotonitazene in 2019. Nitazenes are structurally distinct from fentanyl but share similar pharmacologic and toxicologic activity as mu-opioid receptor agonists with varying degrees of potency. In this study, we report the emergence and subsequent prevalence of the nitazenes in postmortem casework in the State of Maryland between May 2024 and August 2025. Analysis was completed utilizing a mixed-mode cationic exchange solid-phase extraction protocol and detection by ultra-performance liquid chromatography-triple quadrupole mass spectrometry. Four hundred and thirty postmortem cases were analyzed, with 3% of cases positive for one or more nitazenes. The most prevalent nitazenes detected were metonitazene (62% of positive cases), N-desethyl protonitazene (31% of positive cases), and N-pyrrolidino protonitazene (31% of positive cases). Only one case involved nitazenes as the sole substance of toxicologic significance; in all other cases, they were never the only drug detected and were frequently co-detected alongside fentanyl (85% of cases), followed by quinine (77% of cases), despropionyl fentanyl (69% of cases), cocaine/benzoylecgonine (62% of cases), and para-fluorofentanyl (54% of cases). Given the ever-changing landscape of novel psychoactive substances, the potency and increasing prevalence of these synthetic opioids raise significant concerns and underscore the need for ongoing surveillance, advancements in analytical techniques, and targeted public health interventions to mitigate their impact on mortality trends.