Residual effects of zaleplon and zolpidem following middle of the night administration five hours to one hour before awakening

The objective was to assess residual effects of zaleplon and zolpidem after a middle of the night administration. This was a randomized, double-blind, placebo-controlled, crossover study, conducted in 40 healthy young male and female subjects. Subjects were awakened in the middle of the night and administered either placebo or zaleplon 10 or 20 mg or zolpidem 10 mg. A battery of objective tests exploring psychomotor and cognitive functions such as critical flicker fusion (CFF), choice rection time (CRT), digit symbol substitution test (DSST), and memory tests (Sternberg memory scanning and a word list) were administered immediately after morning waking. Zaleplon 10 mg was devoid of residual effects whatever - the time of dosing - except a minimal but significant decrease in DSST scores when administered 1 h before awakening. Zaleplon 20 mg produced significant 'residual effects on performance (increase in CRT, and decrease in CFF threshold and in DSST scores) and memory (decrease in immediate and delayed free recall of words) only when administered Ih before awakening. In contrast, zolpidem 10 mg produced significant detrimental residual effects on CRT and delayed free recall of words, when administered up to 5 h before waking, on DSST and Sternberg when administered up to 3 h before awakening and on CFF when administered 1 h before awakening. The residual effects of zolpidem 10 mg were more marked than those observed after zaleplon 20 mg. The present results demonstrate that zaleplon 10 mg has no or minimal residual effects when administered in the middle of the night as little as 1 h before waking. The lack of clinically significant residual effects with zaleplon may be explained by its unique pharmacokinetic (rapid elimination half-life) and pharmacodynamic (selective binding for GABAA receptors with the al subunit, dissociation between sleep inducing properties and impairment of cognitive functions) profiles. Copyright (C) 2001 John Wiley & Sons, Ltd.