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 effects of zolpidem and zopiclone. Moreover, residual effects of these compounds 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 ocular 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 design. Results: In the 9:00 a.m. group, zolpidem had no residual effects while zopiclone and flunitrazepam both impaired driving performance (P < 0.001 for both) and increased saccadic latency (P < 0.005; P = 0.052, respectively). Zopiclone impaired driving performance 5 times less than did flunitrazepam. In the 11:00 a.m. group, zolpidem and zopiclone had no residual effects, while flunitrazepam increased saccadic latency (P = 0.065) but did not impair driving performance. Conclusions: Zopiclone and flunitrazepam had residual effects in the first part of the morning, whereas zolpidem had no residual effects. The hierarchical character of the effects of the molecules differed according to the test administered. This is probably linked more to drug-induced specific alterations than to different sensitivities of the tests.