Residual effects of zolpidem 10 mg and zopiclone 7.5 mg versus flunitrazepam 1 mg and placebo on driving performance and ocular saccades

Rationale: Studies report contradictory results concerning the residual eff ects of zolpidem and zopiclone. Moreover, residual effects of these compoun ds on healthy subjects have not yet been simultaneously assessed. Objective : The present study with healthy subjects investigated the residual effects of zolpidem 10 mg and zopiclone 7.5 mg on driving performance and on ocula r saccade and compared them to those under flunitrazepam 1 mg and placebo. Methods: The study involved 16 subjects divided into two groups, a 9:00 a.m . group and a 11:00 a.m. group, in a balanced, double-blind, cross-over des ign. Results: In the 9:00 a.m. group, zolpidem had no residual effects whil e zopiclone and flunitrazepam both impaired driving performance (P < 0.001 for both) and increased saccadic latency (P < 0.005; P = 0.052, respectivel y). Zopiclone impaired driving performance 5 times less than did flunitraze pam. In the 11:00 a.m. group, zolpidem and zopiclone had no residual effect s, while flunitrazepam increased saccadic latency (P = 0.065) but did not i mpair driving performance. Conclusions: Zopiclone and flunitrazepam had res idual effects in the first part of the morning, whereas zolpidem had no res idual effects. The hierarchical character of the effects of the molecules d iffered according to the test administered. This is probably linked more to drug-induced specific alterations than to different sensitivities of the t ests.