Metonitazene is considered a new psychoactive substance (NPS) and emerging potent synthetic opioid, causing increased public health concern beginning in 2020. Metonitazene joins a growing list of new synthetic opioids (NSOs) contributing to deaths among people who use drugs in the United States and other parts of the world. Metonitazene (a 2-benzylbenzimidazole analogue) first appeared in mid-2020 in the recreational drug supply and subsequently began proliferating in death investigation casework towards the end of 2020. Screening and metabolite discovery were performed by liquid chromatography quadrupole time-of-flight mass spectrometry. Quantitative confirmation was performed by liquid chromatography tandem quadrupole mass spectrometry. Metonitazene was confirmed in 20 authentic forensic postmortem cases with an average concentration in blood at 6.3 ± 7.5 ng/ml (median: 3.8 ng/ml, range: 0.5–33 ng/ml, n = 18) and in urine at 15 ± 13 ng/ml (median: 11 ng/ml, range: 0.6–46 ng/ml, n = 14). Metonitazene was the only opioid identified in 30% of cases but was also found in combination with fentanyl (55%) and NPS benzodiazepines, opioids, and hallucinogens (45%). Medical examiners included metonitazene as a drug responsible for the cause of death, and the manner of death was always ruled to be an accident. The metabolism of metonitazene was found to be similar to that of isotonitazene, a closely related analogue. Toxicology laboratories and death investigators should ensure that metonitazene is included in forensic testing protocols, all while remaining vigilant for subsequent NSOs to emerge.

中文翻译：

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美国的 Metonitazene——使用液相色谱质谱法对强效新型合成阿片类药物进行法医毒理学评估

Metonitazene 被认为是一种新的精神活性物质 (NPS) 和新兴的强效合成阿片类药物，从 2020 年开始引起越来越多的公众健康关注。Metonitazene 加入了越来越多的新合成阿片类药物 (NSO) 名单，导致美国和美国吸毒者死亡世界其他地区。Metonitazene（一种 2-苄基苯并咪唑类似物）于 2020 年年中首次出现在消遣性药物供应中，随后在 2020 年底开始在死亡调查个案中激增。通过液相色谱四极杆飞行时间质谱法进行筛选和代谢物发现. 通过液相色谱串联四极质谱法进行定量确认。n  = 18)，尿液中浓度为 15 ± 13 ng/ml（中位数：11 ng/ml，范围：0.6–46 ng/ml，n  = 14）。Metonitazene 是唯一在 30% 的病例中发现的阿片类药物，但也发现它与芬太尼 (55%) 和 NPS 苯二氮卓类药物、阿片类药物和致幻剂 (45%) 结合使用。法医将美托尼他列为导致死因的药物，死亡方式始终被裁定为意外。metonitazene 的代谢被发现类似于 isotonitazene，一种密切相关的类似物。毒理学实验室和死亡调查人员应确保法医检测方案中包含美托硝嗪，同时对后续 NSO 的出现保持警惕。