Urinary Screening for Adinazolam and Its Major Metabolites by the Emit ® d.a.u:™ and FPIA Benzodiazepine Assays with Confirmation by HPLC

Adinazolam is a triazolobenzodiazepine, currently under clinical investigation, that possesses antidepressant and anxiolytic activity. It has a short half-life (less than 3 h), and less than 2% of an oral dose is excreted unchanged. The major urinary metabolite is N-desmethyladinazolam, and minor metabolites are estazolam and α-OH-alprazolam. The objective of this study was to characterize the reactivity of adinazolam, N-desmethyladinazolam, and estazolam in the Emit ® d.a.u.™ benzodiazepine assay and the Abbott TDx ® urine (FPIA) benzodiazepine assay. N-desmethyladinazolam and estazolam gave an equivalent response to the Emit cutoff calibrator (300 ng/mL) at 100–200 ng/mL, and adinazolam gave an equivalent response at 200 ng/mL. By FPIA, N-desmethyiadinazolam and adinazolam had equivalent net polarization values as the 300-ng/mL low control at 500–1000 ng/mL, and estazolam gave a positive response at 300 ng/mL. Six volunteers received single oral doses of 10, 30, and 50 mg of adinazolam. Urine specimens (N=7) were collected from 0 to 36 h post-administration. By Emit, all urine specimens at all doses were positive from 2 to 36 h, and all FPIA analyzed specimens were positive from 2 to 24 h. Confirmation testing was performed by HPLC by analyzing for N-desmethyladinazolam. All urine specimens were confirmed positive for N-desmethyladinazoiam (greater than 200 ng/mL) except for the blank specimens (time = 0) and 7 of 18 specimens collected 36 h post-administration. In conclusion, both immunoassay screening assays are acceptable for detecting the presence of adinazolam in human urine for up to 24 h after a single oral dose of 10–50 mg.