Twelve healthy male volunteers were treated (double-blind crossover design) with tofisopam (a new 3,4-benzodiazepine), diazepam, or placebo, on 2 consecutive days each. Psychomotor skills were impaired after a single dose of diazepam (10 mg) given on day 1. Measurements on day 2 showed that some tolerance had developed to the diazepam-induced impairment of reactive and coordinative skills, but not to its effects on flicker fusion or on the extraocular muscle balance. Tofisopam failed to impair performance both as a single dose (100 mg) and after repeated doses (100 + 50 + 50 + 100 mg). The subjects felt more fatigue, dizziness, calmness, and passiveness after diazepam than after tofisopam. When either drug was given together with 0.8 g/kg ethanol on day 2, the breath ethanol concentrations were 0.7--1.0 mg/ml and all psychomotor skills were impaired. Diazepam + ethanol particularly impaired memory and learning as well. After this combination the subjects were classified (time anticipation test) as 'disqualified drivers' more often than after placebo. It is concluded that diazepam, as well as either benzodiazepine with ethanol, may reduce the ability to drive vehicles or operate machinery.
The serotonin 5-hydroxytryptamine-1A (5-HT1A) receptor agonists buspirone and gepirone have effects on serotonergic systems, including presynaptic and postsynaptic receptors, that predict both anxiolytic and antidepressant activity. Chronic administration of both drugs produces a down-regulation of 5-HT2 receptors, a finding common to most antidepressant drugs irrespective of mechanism of action. In addition, gepirone induces a full-blown serotonin syndrome in rodents and is active in the behavioral despair test mediated by an action on serotonergic neurons. Buspirone is active in this paradigm when injected directly into the serotonergic dorsal raphe nucleus. The therapeutic effects of both buspirone and gepirone have been assessed in placebo-controlled studies of patients with major depression. Findings in these studies support antidepressant efficacy in addition to anxiolysis. In double-blind studies of patients with major depression treated for 8 weeks, each drug was found to be superior to placebo in improvement in Hamilton Depression and Anxiety total scores as well as individual depressive symptoms. These clinical findings are consistent with preclinical pharmacology suggesting that 5-HT1A partial agonists may possess intrinsic antidepressant activity.
Two doses of buspirone (5 and 10 mg tds), 1 dose of diazepam (5 mg tds) and placebo were administered to 8 normal subjects for a period of 8 days. Each subject received each drug in a balanced order with a minimum interval of 1 week between courses. Psychotropic effects were assessed with a battery of physiological, psychomotor and subjective tests on the first, third and last days of treatment both before the first daily dose and at 1 h and 3 h after it. Diazepam showed a characteristic profile of action producing EEG changes and psychological impairment after a single dose which were still present after a week's treatment. Such effects were minimal after buspirone. Both drugs increased subjective ratings of drowsiness but these feelings tended to decrease after a week's treatment on the clinical doses. Buspirone (10 mg tds) produced some unpleasant side-effects initially but tolerance to these invariably developed after 3 days treatment.
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