Triazolam and zolpidem: a comparison of their psychomotor, cognitive, and subjective effects in healthy volunteers

The psychomotor/cognitive performance, subject-rated, and observer-rated effects of single oral doses of the benzodiazepine hypnotic triazolam (0.125, 0.25, and 0.5 mg/70 kg) and the imidazopyridine hypnotic zolpidem (5, 10, and 20 mg/70 kg) were compared in 11 volunteers, in a double-blind, placebo-controlled, crossover design. Triazolam and zolpidem produced similar dose-related decrements on several performance measures, and similar dose-related increases on most observer-rated and several subject-rated measures. The drugs differed in the time course of their effects on these measures; the effects of zolpidem typically peaked 30 min earlier (1-1.5 h postdrug) than the effects of triazolam (1.5-2 h postdrug). Triazolam and zolpidem produced a different profile of effects on other performance measures which could not be attributed to time course differences. Triazolam produced significantly more impairment than zolpidem in time estimation. Triazolam, but not zolpidem, produced significant impairment on a short-term memory task. Zolpidem produced significantly more impairment than triazolam on several novel measures of performance on a computerized trail-making test. The observed differences between triazolam and zolpidem may be related to zolpidem's reported binding selectivity for the omega 1 receptor subtype.