The appearance of pyrazolam in Internet shops selling 'research chemicals' in 2012 marked the beginning of designer benzodiazepines being sold as recreational drugs or 'self medication'. With recent changes in national narcotics laws in many countries, where two uncontrolled benzodiazepines (phenazepam and etizolam), which were marketed by pharmaceutical companies in some countries, were scheduled, clandestine laboratories seem to turn to poorly characterized research drug candidates as legal substitutes. Following the appearance of pyrazolam, it comes with no surprise that recently, flubromazepam (7-bromo-5-(2-fluorophenyl)-1,3-dihydro-2H-1,4-benzodiazepin-2-one), a second designer benzodiazepine, was offered on the market. In this article, this new compound was characterized using nuclear magnetic resonance, gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS/MS) and liquid chromatography quadrupole time-of-flight MS (LC-Q-ToF-MS). Additionally, a study was carried out, in which one of the authors consumed 4 mg of flubromazepam to gain preliminary data on the pharmacokinetic properties and the metabolism of this compound. For this purpose, serum as well as urine samples were collected for up to 31 days post-ingestion and analyzed applying LC-MS/MS and LC-Q-ToF-MS techniques. On the basis of this study, flubromazepam appears to have an extremely long elimination half-life of more than 100 h. One monohydroxylated compound and the debrominated compound could be identified as the predominant metabolites, the first allowing a detection of a consumption for up to 28 days post-ingestion when analyzing urine samples in our case. Additionally, various immunochemical assays were evaluated, showing that the cross-reactivity of the used assay seems not to be sufficient for safe detection of the applied dose in urine samples, bearing the risk that it could be misused in drug-withdrawal settings or in other circumstances requiring regular drug testing. Furthermore, it may be used in drug-facilitated crimes without being detected.

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Since their first appearance on the Internet in 2012, designer benzodiazepines established as an additional, quickly growing compound class among new psychoactive substances. Data regarding pharmacokinetic parameters, metabolism, and detectability for new compounds are limited or often not available. One of these compounds, flubromazolam (8-bromo-6-(2-fluorophenyl)-1-methyl-4H-[1,2,4]triazolo [4,3-a][1,4]benzodiazepine), the triazolo-analogue of flubromazepam, has been offered on the Internet from 2014 on. The purpose of the present study was to assess the period of detectability in biological samples along with preliminary basic pharmacokinetic parameters of the designer benzodiazepine flubromazolam. To investigate these, one of the authors ingested a capsule containing 0.5 mg of the drug. Metabolism studies and suitability tests for the detection with immunochemical assays were performed with the samples obtained from the self-experiment and five authentic case samples. Flubromazolam and its mono-hydroxylated metabolite were detectable by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in urine for up to 6.5 and 8 days, respectively (lower limit of quantification (LLOQ) flubromazolam: 0.1 ng/mL). Peak serum concentrations were as low as 8 ng/mL (8 h post ingestion). Glucuronides were also detected. The terminal elimination half-life could be estimated in the range of 10-20 h. Immunochemical assays yielded negative results for serum samples and positive results for urine samples for up to five days post ingestion. The presented data demonstrate the detectability of a single uptake of 0.5 mg of flubromazolam in hair samples collected two weeks after drug uptake by LC-MS 3 (c max 0.6 pg/mg; LOD 0.01 pg/mg). The detected metabolites were in good agreement with those described in other studies.