Effects of daytime administration of zolpidem and triazolam on performance

BACKGROUND AND HYPOTHESES: The performance-impairing effects of the short-acting imidazopyridine zolpidem (Ambien) were compared to those of triazolam (Halcion) following daytime administration.

There were 70 male subjects who received oral zolpidem (5, 10 or 15 mg), triazolam (0.125, 0.25 or 0.5 mg), or placebo at 1000 hours. Performance on Logical Reasoning, Column Addition, and Repeated Acquisition (computerized tasks of the Walter Reed Performance Assessment Battery) was assessed prior to drug administration, then at 1.5 h (estimated time of peak drug effects) and 6 h post-administration.

Number of trials completed (TC) and response time (RT) for correct answers on the Logical Reasoning (LR) and Column Addition (CA) tasks (expressed as percentage of pre-drug performance) were impaired by triazolam 0.5 mg (TC = 76.6 and 67.4% for LR and CA; RT = 182.1 and 127.0% for LR, CA) and zolpidem 15 mg (TC = 87.0 and 75.8% for LR, CA; RT = 198.7 and 161.8% for LR, CA) at 1.5 h post-administration. By 6 h post-administration, drug effects on performance had dissipated. Other doses of triazolam and zolpidem failed to impair performance significantly.

These results indicate substantial performance impairment at estimated peak plasma concentrations of both triazolam and zolpidem, at or near doses coinciding with somnogenic efficacy. Thus, the present results suggest no advantage of benzodiazepine receptor-subtype-specific drugs (e.g., zolpidem). Rather, these results suggest that the performance-impairing effects of both drugs are dose-dependent and functionally coupled to their sleep-inducing properties.