N-pyrrolidino isotonitazene and its metabolites in post-mortem casework

N-pyrrolidino isotonitazene (Isotonitazepyne) is an extremely potent novel synthetic opioid which has been detected internationally in counterfeit pharmaceutical tablets. Published data from post-mortem cases is extremely limited and no metabolite profiles from authentic case work have been published. This paper describes a number of post-mortem cases in which N-pyrrolidino isotonitazene was thought to play a significant role in the cause of death, as well as describing the detected metabolite profiles. Concentration ranges for N-pyrrolidino isotonitazene was reported to be 1.1-55.9 µg/L across the 4 cases. The presumptive metabolite 5-amino-N-pyrrolidino isotonitazene was also identified in all samples; n-pyrrolidino-4-hydroxy nitazene was present in 3 of the 4 urine samples; and N-pyrrolidino hydroxy isotonitazene was present in 1 sample. This study highlights some of the challenges associated with nitazene interpretation, such as the very wide concentration ranges encountered in potentially fatal cases, as well as providing provisional metabolite data which may aid in detecting future cases.