Alprazolam and lorazepam single and multiple-dose effects on psychomotor skills and sleep

Abstract

The effects of alprazolam 0.5 mg and lorazepam 2 mg on cognitive and psychomotor skills were assessed in twelve normal volunteer subjects in a randomised, double-blind, crossover design. Single and multiple dose effects were monitored using a battery of tests comprising critical flicker fusion threshold (CFFT), choice reaction time (CRT), simulated car tracking, and subjective ratings of perceived sedation (LARS) and of sleep behaviour (LSEQ). Compared with placebo baseline scores, treatment with lorazepam 2 mg (both single and multiple doses) resulted in a widespread impairment of CRT, tracking accuracy, and CFFT. Single doses of alprazolam 0.5 mg reduced CFFT with respect to the placebo baseline. Single and multiple dose treatment with both drugs resulted in subjective reports of sedation, a reduction of sleep onset latency, and improved sleep quality. Only lorazepam 2 mg significantly disrupted the integrity of behaviour on waking from sleep. These results suggest important pharmacodynamic differences between the two drugs in the doses used.

Effects of alprazolam and lorazepam on catecholaminergic and cardiovascular activity during supine rest, mental load and orthostatic challenge

“…Our results are in line with previous studies reporting increases in subjective sedation after 0.5 or 1.0 mg alprazolam (Dawson et al 1984;Subhan et al 1986;Greenblatt et al 1988;Risby et al 1989). …”

“…Memory impairment and performance deterioration to psychological tasks after a dose of 2 mg lorazepam are well documented (Subhan et al 1986;Greenblatt et al 1988;Preston et al 1989;Tulen et al 1991). Similar effects have been reported after alprazolam (Subhan et al 1986;Greenblatt et al 1988;Linnoila et al 1990). However, at the present dose levels of alprazolam, subjective sedation was not accompanied by performance impairment to the CWT.…”

“…Since there were no differences regarding subjective sedation, it is remarkable that performance to the CWT was deteriorated only after LOR administration. Memory impairment and performance deterioration to psychological tasks after a dose of 2 mg lorazepam are well documented (Subhan et al 1986;Greenblatt et al 1988;Preston et al 1989;Tulen et al 1991). Similar effects have been reported after alprazolam (Subhan et al 1986;Greenblatt et al 1988;Linnoila et al 1990).…”

“…In humans, alprazolam may suppress adrenergic as well as noradrenergic function, although conflicting data exist (Stratton and Halter 1985;Risby et al 1989;Linnoila et al 1990;McLeod et al 1990;Breier et al 1992;Osman et al 1993). Studies in humans have also suggested that there are differences between benzodiazepines with respect to sedative properties: alprazolam may induce less sedation in comparison with clinically equivalent doses of other benzodiazepines (Dawson et al 1984;Subhan et al 1986;Greenblatt et al 1988).…”

Effects of Alprazolam on Driving Ability, Memory Functioning and Psychomotor Performance A Randomized, Placebo-controlled Study

“…Behavioral studies with healthy volunteers generally show a change from baseline performance on laboratory tests after chronic administration of alprazolam (e.g. Aranko et al 1985, Seidel et al 1985, Subhan et al 1986, Kumar et al 1987, Smith and Kroboth 1987, Jurado et al 1989, Hart et al 1991, Pomara et al 1998. It is however unclear whether this effect is caused by the development of tolerance to alprazolam's sedative effects, or due to learning effects.…”