A Two-Year Evaluation of Flualprazolam Concentrations in Orange County Drivers: Effects on Driving and Field Sobriety Test Performance.

Starting in early 2017, flualprazolam was detected in toxicology and seized drug cases across the USA. Due to the addition of fluorine to alprazolam, flualprazolam's chemistry was enough to bypass targeted toxicology confirmations, and it has become increasingly available for purchase both on the dark web and in counterfeit pills. Flualprazolam was added to the exact mass screening regiment of the Orange County forensic laboratory in December 2018. Through data mining of previously analyzed cases, data were evaluated beginning from August 2018. Flualprazolam was subsequently added to the laboratory's validated quantitative liquid chromatography dual mass spectrometry method in the summer of 2020, and all driving cases from August 2018 to June 2020 were re-analyzed to obtain concentrations. The police and drug recognition evaluation (if available) reports were collected and reviewed for all cases where flualprazolam was detected. Of the 203 cases containing quantifiable drug, the average flualprazolam concentration (median, range) was 22.8 ng/mL (15.4 ng/mL, 4.0-133.3 ng/mL). Only two cases had flualprazolam detected with no other drugs. The other most common drugs detected were cannabinoids (62%), ethanol (20%) and cocaine and/or methamphetamine (32%). The most common reason for the police investigation was an accident/collision (50%), and the most common time of officer contact was evening (18:00 to 23:59). The field sobriety test (FST) results were evaluated and showed a higher frequency of impaired performance in cases of flualprazolam in combination with other drugs. No conclusion could be made regarding the effect of flualprazolam alone on FST performance.