Characterization of the designer benzodiazepine pyrazolam and its detectability in human serum and urine

In 2012, online shops selling so-called research chemicals started offering pyrazolam, a new benzodiazepine that differs from phenazepam and etizolam, which have also recently appeared on the “gray market”, in that it is not marketed by pharmaceutical companies anywhere in the world. This article describes the characterization of pyrazolam (8-bromo-1-methyl-6-pyridin-2-yl-4H-[1,2,4]triazolo[4,3–a][1, 4]benzodiazepine) using gas chromatography-mass spectrometry, liquid chromatography-tandem mass spectrometry (LC–MS–MS), liquid chromatography quadrupole time-of-flight mass spectrometry (LC–Q–TOF–MS), and nuclear magnetic resonance spectroscopy. In addition, a study was carried out in which one of the authors ingested two 0.5-mg pyrazolam tablets. Serum and urine samples were then obtained to investigate the metabolism of pyrazolam and to obtain preliminary results for the elimination half-life and the detectability of a 1-mg dose in serum and urine using a highly sensitive LC–MS–MS method and immunoassays. The results showed an elimination half-life of about 17 h and no detectable metabolism. The parent compound was detected with the described LC–MS–MS method in serum for more than 50 h and in urine for approximately 6 days. Immunoassays showed cross-reactivity, but poor detection in the study samples demonstrated that consumption or administration of this presumably potent drug could go undetected unless instrumental analytical techniques are also used.