Residual Next-Day Effects of Alprazolam on Psychomotor Performance and Simulated Driving in Healthy Normal Adults

The prevalence of drugged driving has increased in the United States. Some drugged driving may be unintentional as prescription medications used as sleeping aids, like zolpidem, cause impairment after the predicted duration of therapeutic action has elapsed. The aim of this study was to determine if nighttime administration of alprazolam, a drug commonly prescribed off-label as a sleeping aid, impacts driving performance the following day. Participants were healthy adults (n = 15) who completed a double-blind, double-dummy, within-subjects inpatient study examining the effects of nighttime administration of alprazolam (0.5, 1, and 2 mg), zolpidem (10 mg), and placebo on driving performance the following day. Alprazolam (1 mg; morning) and zolpidem (nighttime) both served as positive control conditions. Driving simulator measures, cognitive and psychomotor tasks, and questionnaires querying drug effects were collected the afternoon before drug administration and for 5.5 hr the next day and analyzed using symmetry and mixed-model approaches. Morning alprazolam significantly impaired driving performance. Driving impairment was observed up to 12.5 hr after nighttime alprazolam 2 mg and for 8.5 hr after nighttime zolpidem 10 mg. Participant reports on driving ability indicated that they were not aware of their level of impairment. These results suggest that alprazolam used before bed may pose a yet unrecognized public safety risk in the form of next-day drugged driving.