First report on brorphine : the next opioid on the deadly new psychoactive substance horizon?

New psychoactive substances (NPS) continue to appear on the drug market. Until recently, new synthetic opioids, which are amongst the most dangerous NPS, primarily encompassed analogues of the potent analgesic fentanyl. Lately, also other new synthetic opioids have increasingly started to surface. This is the first report on the identification and full chemical characterization of brorphine, a novel potent synthetic opioid with a piperidine benzimidazolone structure. Brorphine was identified in a powder and in the serum of a patient seeking medical help for detoxification. Liquid chromatography–high resolution mass spectrometry (LC–HRMS) identified an exact mass of m/z 400.1020 and 402.1005 for the compound, corresponding to both bromine isotopes. Further chemical characterization was performed by gas chromatography–mass spectrometry (GC–MS), LC–diode array detection (DAD) and Fourier-transform infrared (FT-IR) spectroscopy analyses. Finally, the structure was confirmed by performing 1H- and 13C-NMR spectroscopy. In vitro biological activity of brorphine was determined by a cell-based µ-opioid receptor (MOR) activation assay, resulting in an EC50 of 30.9 nM (13.5 ng/mL) and an Emax of 209% relative to hydromorphone, confirming the high potency and efficacy of this compound. In a serum sample of the patient, brorphine and a hydroxy-metabolite were found using the LC–HRMS screening method. The presence of opioid activity in the serum was also confirmed via the activity-based opioid screening assay. The occurrence of brorphine is yet another example of how the illicit drug market is continuously evolving in an attempt to escape international legislation. Its high potency poses a serious and imminent health threat for any user