Evaluation of the metabolites 5‐aminoisotonitazene, 4′‐hydroxy nitazene, N‐desethyl isotonitazene, and N‐desethyl metonitazene in authentic isotonitazene and metonitazene positive postmortem cases

Benzimidazole opioids, isotonitazene (ITZ), and metonitazene (MTZ) and their associated metabolites, 5-aminoisotonitazene (5-AI), 4'-hydroxy nitazene (4'-HN), N-desethyl isotonitazene (N-DI), and N-desethyl metonitazene (N-DM), were evaluated in human postmortem casework. A total of twenty-seven cases that previously tested positive for ITZ (n = 11) and MTZ (n = 16) in routine case analysis were retested for the presence of metabolites in blood and urine specimens by solid-phase extraction and LC/MS/MS. N-DI was the most prevalent metabolite detected in ITZ cases, present in six blood and four urine samples. N-DM was the most prevalent MTZ metabolite, primarily found in urine. 4'-HN was detected in both ITZ and MTZ cases. Fentanyl was the most prevalent co-finding, and all cases were classified as mixed drug intoxications except for two blunt force traumas. Due to the reported potency of N-DI and prevalence of metabolite detection in these cases, this study encourages the addition of nitazene metabolites to routine testing scopes.