Identification of 5-fluoro ADB in human whole blood in four death cases

Four deaths that seemed to have been caused by a designer drug occurred within a 3-week period in Sendai, Japan. In each case, the decedent possessed the same sachet, labeled "Heart Shot BLACK", which contained a dried plant material with an aromatic scent. It was revealed in our analysis that the product contained a synthetic cannabinoid receptor agonist, 5-fluoro ADB (methyl 2-[1-(5-fluoropentyl)-1H-indazole-3-carboxamide]-3,3-dimethylbutanoate, also known as 5-fluoro MDMB-PINACA), which is now classified as a restricted designer drug in Japan after it caused several casualties. For standard samples, the detection of 5-fluoro ADB in whole blood in the calibration range (0.04-4 ng/mL) was successful with recoveries of 94.6-98.1%, limits of detection of 6 pg/mL, and limits of quantification of 40 pg/mL. The intraday and interday precisions were 0.9-4.8% and 1.1-6.6%, respectively. The bias was -1.1 to 2.9%. We were able to confirm that 5-fluoro ADB was present in the blood of all four decedents at a concentration of 0.11-1.92 ng/mL. From the autopsy, toxicological findings, and circumstances surrounding the cases, it was considered that inhalation of 5-fluoro ADB could have contributed to the deaths. However, the extent to which 5-fluoro ADB contributed to the deaths remains unclear due to the current lack of toxicological information on the compound. In future research, the toxicity of 5-fluoro ADB in humans and the mechanism underlying this effect need to be elucidated.