No abstract

The effects of two benzodiazepine anticonvulsants clobazam (20 mg) and clonazepam (2 mg) in a variety of psychomotor performance tests were compared in a placebo controlled double-blind acute oral dose study in ten healthy volunteers. Assessments included critical flicker fusion (CFF) threshold, the Sternberg memory scanning and choice reaction time (CRT), peak saccadic velocity (PSV) and visual analogue scales, all previously shown to be sensitive to the effects of benzodiazepines. Clobazam did not significantly impair saccadic eye movements, CFF threshold, Sternberg memory scanning and CRT compared to placebo. Clonazepam significantly lowered PSV, reduced the CFF threshold, slowed the Sternberg CRT and decreased an alertness factor in the visual analogue scales compared to placebo. Clonazepam significantly increased memory scanning time compared to clobazam. Clobazam was remarkably free of cognitive and psychomotor side-effects.

We investigated the effects of single doses of the dopamine agonist levodopa and the dopamine antagonist haloperidol on pattern and flash electroretinograms (ERGs) and visual evoked potentials (VEPs) in normal subjects. A placebo and two treatment regimens were administered in a randomized double-masked design. No significant intertreatment differences in the pattern ERGs and VEPs were noted. Although not statistically significant, a clearly discernible tendency was found for increased flash ERG b-wave amplitudes after levodopa administration compared with placebo. In comparison with placebo and levodopa, haloperidol was associated with significantly prolonged flash ERG b-wave implicit times, including each oscillatory potential, which also showed increased duration, particularly in the O1-O3 interpeak implicit time. The failure of pattern ERGs and VEPs to show changes after haloperidol may have been related to the timing of the recordings, which took place during the presumed phase of rising blood levels and before the flash ERG and VEP recordings. Our findings further demonstrated the reliability of the flash ERG in revealing changes in dopaminergic status in the visual system and suggest that steady-state (flicker) ERGs, cone ERGs, and oscillatory potentials have particular use in this regard.

The effects of a single oral dose of alprazolam (1 mg), quazepam (15 mg) and diazepam (10 mg) on the peak saccadic velocity (PSV) of saccadic eye movements (SEM), the Sternberg memory scanning and choice reaction time (SMS-CRT), critical flicker fusion frequency (CFFF), spectral analysis of the EEG and a mood scale were assessed in 9 healthy volunteers in a double-blind, placebo-controlled cross-over study. Alprazolam revealed greater sedative effects than diazepam in the above-mentioned tests. Quazepam had the least sedative effect of the 3 drugs tested, showed a time lag at the onset of its effects and a more prolonged effect on psychomotor impairment than reported previously.

This study compares the effects of buspirone (5 mg), chlordiazepoxide (5 mg), hydroxyzine (10 mg) and placebo on psychomotor function and EEG, when taken thrice daily for a period of two weeks, with those after a single dose administration. Nine healthy volunteers participated in the study. The battery of psychomotor tests included peak velocity of saccadic eye movements (SEM), a Sternberg memory scanning and choice reaction time test (SMS-CRT) and critical flicker fusion frequency (CFFF). The peak velocity of saccadic eye movements was significantly impaired by the single dose of hydroxyzine (P = 0.03) in comparison to the multidose results. A similar comparison regarding buspirone only approached significance (P = 0.07). The SMS-CRT and CFFF did not reveal any difference between the multi and single dose regimens. Spectral analysis of the EEG did not distinguish between the multi and single dosage schedules regarding the respective drugs in the low doses administered.