Saccadic eye movements in determination of the residual effects of the benzodiazepines.

Saccadic eye movements and the volunteers' subjective assessments were used in the determination of the residual effects of a single high evening dose of flunitrazepam 2 mg, midazolam 30 mg, and lorazepam 2.5 mg as well as in that of placebo. Sleep inducing and maintaining effects were subjectively assessed, too. Both flunitrazepam 2 mg, midazolam 30 mg, and lorazepam 2.5 mg possessed sleep inducing and increasing effects (n = 9), but in the number of nocturnal awakenings and quality of sleep no significant differences between placebo and the active medications were reported. Flunitrazepam 2 mg and lorazepam 2.5 mg produced distinct subjective residual effects thus differing from placebo and midazolam 30 mg. Despite this, saccadic eye movement recording could further differentiate midazolam 30 mg from placebo in this respect 10 hours after drug intake. After three repeated 2 mg evening doses, flunitrazepam accumulated in the serum of the volunteers (n = 6), but the effect on saccadic eye movements as well as subjective side effects began to decrease already after one day's treatment. Thus, saccadic eye movement recording proved to be a useful tool in determining the residual effects and development of tolerance of benzodiazepines. No correlation was detected between the serum levels (radioreceptor assay) and saccadic eye movement recordings or subjective residual sequelae.