Effects of benzodiazepine (diazepam, lorazepam) and benzodiazepine-like anxiolytics (alpidem, suriclone) and a 5-HT-3 antagonist (ondansetron) on actual driving performance were measured in three double-blind, placebo-controlled studies. Subjects were healthy volunteers in two and anxious patients in the third. Treatments lasted for 8 days. Standardized testing occurred within the first full day and on the last day of treatment. No important differences existed between volunteers’ and patients’ baseline and/or placebo performances and both groups responded similarly to comparable drugs/doses. Benzodiazepine and benzodiazepine-like anxiolytics produced marked and pervasive driving impairment, which lasted throughout treatment; but ondansetron, none.

Mefloquine did not impair driving performance but rather improved it in the longer test, suggesting that the drug may possess psychostimulating properties.

Eighteen healthy volunteers participated in a randomized, double blind, cross-over trial. They received mirtazapine, mianserin or placebo during separate periods of 15 days. Mirtazapine and mianserin were respectively administered in doses of 15 mg and 30 mg nocte for the ®rst 7 days and doses of 30 mg and 60 mg nocte for the remaining 8 days. Assessments were made at baseline and on days 2, 8, 9 and 16 of each period to compare eects of drugs and placebo on mood, psychomotor (CTT, CRT, CFF and Vigilance) and`actual' driving performance. Sleep quality and duration and side-eects were assessed at baseline and every treatment day. Mirtazapine 15 mg and mianserin 30 mg slightly impaired psychomotor and driving performance on day 2 of treatment. On day 8, the eects were virtually gone, although some driving impairment could still be observed in the mianserin condition. No drug eects on performance were found on day 9 despite the dose escalation. On day 16 of treatment, driving performance and vigilance slightly decreased in, respectively, the mirtazapine and the mianserin conditions. These eects indicate that tolerance to the drugs' adverse eects was not complete. This observation was also supported by subjective data. Similar increments in sleep duration and feelings of lethargy, drowsiness and weakness were observed throughout treatment with both drugs. Alertness and contentedness was always lower during both drug treatments than with placebo. Spontaneously reported adverse events were similar to self-rated side-eects and more of both were recorded during mianserin treatment. It is concluded that the acute and subchronic eects of nocturnal doses of both drugs were similar and equally low in magnitude. Eects on performance were much less than those seen in other studies after administration during the day. Full daily doses of both drugs should be prescribed in nocturnal dosing regimens, and not in divided doses over the day, for avoiding excessive sedation and performance impairment.

The effects of befloxatone (20 mg o.d. for 10 days) alone and in combination with ethanol on psychomotor performance, memory and mood were assessed in a randomized, double-blind, placebo controlled study. On treatment days 6, 8 and 10, subjects received 0.5 and 0.8 g/kg ethanol and ethanol placebo in randomly assigned, balanced orders, 2 h post-drug. Critical fusion frequency, choice reaction time, postural instability, critical tracking and mood were measured 1h before ethanol and 1, 3 and 5 h afterwards. Divided attention, sustained attention and memory (immediate and delayed recall) were also measured in single tests, 2.5-5 h post-ethanol.Ethanol's effects were generally significant when blood alcohol concentrations (BAC) after both doses were the highest; i.e. 0.48-0.67 and 0.96-1.10 mg/ml. Those effects were virtually gone after the subjects' mean BACs fell below 0.40 mg/ml. Befloxatone alone had no significant impairing effect in any test. Neither did it significantly interact with ethanol to cause any greater impairment than the latter alone. It was concluded that befloxatone does not potentiate the sedating and impairing effects of ethanol.