A case of acute intoxication due to combined use of fentanyl and 3,4-dichloro-N-[2-(dimethylamino)cyclohexyl]-N-methylbenzamide (U-47700)

U-47700 is an opioid analgesic drug, considered to have a potency of approximately 7.5 times that of morphine. A target analysis on U-47700 was performed using liquid-liquid extraction and ultra performance liquid chromatography tandem mass spectrometry operating in multiple reaction monitoring mode. The method validation was based on the Scientific Working Group of Forensic Toxicology document 'Standard Practices of Method Validation in Forensic Toxicology'. In blood and urine the U-47700 concentration was 13.8 and 71.0 μg/L, respectively. To the author's knowledge, this is the first case report of a fatal intoxication involving U-47700 abused as a new psychotropic substance.