Effects of alprazolam, caffeine, and zolpidem in humans trained to discriminate triazolam from placebo

This study compared the discriminative stimulus effects of zolpidem, a nonb enzodiazepine hypnotic, to benzodiazepines. Eight participants learned to d iscriminate triazolam (0.35 mg/70 kg) from placebo. The discriminative stim ulus effects, self-reported subjective effects, and performance effects of triazolam (0.05-0.35 mg/70 kg), alprazolam (0.25-1.75 mg/70 kg), zolpidem ( 2.5-35 mg/70 kg) and caffeine (75-525 mg/70 kg) were assessed under two-res ponse and novel-response drug discrimination procedures. Under the two-resp onse procedure, triazolam, alprazolam and zolpidem fully substitued for tri azolam and caffeine did not. Under the novel-response procedure, triazolam and alprazolam substituted for triazolam and zolpidem partially substituted for triazolam. Zolpidem, but not triazolam or alprazolam, also produced so me novel responding. Caffeine produced both placebo-appropriate and novel r esponding. The self-reported effects of triazolam, alprazolam and zolpidem were similar. Overall, zolpidem produced similar, but not identical, effect s as the benzodiazepines. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.