Nomifensine, clobazam and HOE 8476: effects on aspects of psychomotor performance and cognitive ability

Subjective assessment of the effects of CNS-active drugs on sleep by the Leeds sleep evaluation questionnaire: a review

The Leeds sleep evaluation questionnaire (LSEQ) comprises ten self-rating 100 mm line analogue questions concerned with sleep and early morning behaviour. A literature search identified 83 studies in peer-reviewed journals that reported the use of the LSEQ for psychopharmacological investigations of drug effects on self-reported aspects of sleep. High internal consistency and reliability of the questionnaire have been demonstrated. Findings from studies involving a variety of psychoactive agents indicated that the LSEQ was able to quantify subjective impressions of sleep and waking and the effects of drugs in healthy volunteers, depressed and insomnia patients. In accordance with their known activity profile nocturnal administration of sedative hypnotic agents and antihistamines induced dose-related improvements in self-reported ease of getting to sleep, and quality of sleep but a decrease in alertness and behavioural integrity the following morning. Psychostimulants, on the other hand, impaired subjective ratings of sleep and increased early morning alertness. Antidepressants and certain anxiolytic agents improved both self-reported sleep aspects and early morning alertness. Treatment effects measured by the LSEQ corresponded to those measured for the same drugs by other assessment methods. These data indicate that the LSEQ is a robust and reliable instrument for psychopharmacological evaluations. Self-evaluations of sleep, as obtained by the LSEQ, can therefore provide consistent and meaningful measures for estimating the effectiveness of sleep modulators and sedative-hypnotic drugs.

A review of the effects of dopaminergic agents on humans, animals, and drug-seeking behavior, and its implications for medication development. Focus on GBR 12909

Medication development for cocaine abuse has focused on potential mechanisms of action related to the abuse of cocaine. The hypothesis that mesolimbic dopamine (DA) is the key neurochemical mediator of cocaine's addictive and reinforcing effects is well supported by a wide variety of data from animal studies. On the other hand, medications that increase DA or block its action in humans can produce effects that appear incompatible with this hypothesis. This article reviews these incompatibilities between animal and human data with a focus on the DAergic actions of drugs, including DA reuptake inhibitors, direct DA agonists, DA increasers, and DA antagonists. Possible reasons for these discrepancies are discussed, and the potential role of high-affinity DA uptake inhibitors, such as GBR12909, for pharmacotherapies for treating cocaine addiction in humans is likely to come from understanding its mechanisms of action, it is clear that further research on the effects of cocaine in humans and animals will be critical to the medication development effort.

GBR12909 antagonizes the ability of cocaine to elevate extracellular levels of dopamine

Rats were administered various IP doses of the high-affinity dopamine (DA) reuptake inhibitor 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-[3-phenylpropyl]piperazine (GBR12909). The caudate nuclei were removed 60 min after drug administration and stored at -70 degrees C. Striatal membranes were prepared later. The results demonstrated that GBR12909 produced a dose-dependent decrease in the binding of [3H]cocaine or [3H]GBR12935 to the DA transporter (ED50 about 10 mg/kg). Saturation binding studies with [3H]GBR12935 showed that this was due to both an increase in the Kd, due to residual drug, and to a decrease in the Bmax. At a dose of 25 mg/kg IP, GBR12909 produced a 50% decrease in the Bmax, and a 3.4-fold increase in the Kd. In the in vivo microdialysis studies, GBR12909 (25 mg/kg IP) produced a modest, long-lasting and stable elevation of extracellular DA. Administration of cocaine through the microdialysis probe to rats pretreated with either saline or GBR12909 (25 mg/kg IP) produced a dose-dependent increase in extracellular DA in both groups. GBR12909 inhibited cocaine-induced increases in extracellular DA by about 50% at all doses. These data collectively indicate that at a dose sufficient to decrease by 50% the Bmax of [3H]GBR12935 binding sites, GBR12909 antagonizes the ability of cocaine to elevate extracellular DA by 50%. Further studies will be needed to evaluate a possible role for GBR12909 in the medical treatment of cocaine addiction.

Actions and interactions of psychotropic drugs on human performance and mood: single doses of ORG 3770, amitriptyline, and diazepam

Actions and interactions of two antidepressants and diazepam on human skilled performance and mood were studied in a randomized double-blind cross-over trial with single oral doses of 50 mg amitriptyline (AMI), 15 mg Org 3770 (ORG) and placebo, given alone and in combination with 15 mg diazepam (DZ) to 12 young healthy subjects at one-week intervals. Objective tests (digit substitution, tapping, flicker fusion, Maddox wing, tracking, choice reactions, body sway, memory) and subjective assessments (visual analogue scale) were performed at baseline and 1.5, 3, 4.5 and 6 hours after drug administration. Side-effects were reported, blood pressure and heart rate measured and blood samples taken after each testing run. Placebo was nearly inert on performance and mood. DZ impaired some objective skills and showed sedative effects in the subjective tests. AMI produced sedation and impaired coordination as well as cognitive performance (digit substitution), most clearly at 3 to 4.5 hr. ORG resembled AMI in impairing objective and subjective performance, however, not necessarily in the same tests. Their combined effects with DZ were additive in objective tests but less additive in subjective tests. The drug combinations, but not any single drug, impaired learning acquisition. Plasma concentrations of the drugs given alone were about as expected, without important interactions. We conclude that the combinations of benzodiazepines with the antidepressants used impair skilled performance but may not cause major hazards.

Effects of clobazam and clonazepam on saccadic eye movements and other parameters of psychomotor performance

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.

Assessment of the effects of drugs on memory

This survey is based on 70 controlled investigations of the effects of drugs on memory in healthy volunteers. Although detracting effects were predominant, enhancements were reported as well. The effects of 29 well-known drugs on 15 familiar tests are summarized in a way that permits comparisons of the effects of different drugs and of test sensitivities. There is a discussion of factors that could bias or obscure investigations of the effects of drugs on learning and remembering.

Acute effects of amitriptyline on human performance and interactions with diazepam

The effects of psychomotor performance and attention of amitriptyline 75 mg administered without and with diazepam 10 mg have been investigated in 12 healthy subjects. The effects of the compounds were evaluated by objective tests (measurement of body sway, critical flicker fusion, visual reaction time, tachistoscopy, short term visual memory, tapping test, arithmetical calculation and Clement's code) and subjective measurements (visual analogue scales and side effects questionnaire). Measurements were taken before treatment and after 1, 3, 6, 8 and 24 h. Placebo did not affect either the objective or the subjective measurements. Diazepam caused a reduction in attention and performance after 1 h which had disappeared at 3 h. Amitriptyline caused a marked reduction in attention and performance, reaching a peak 3 hours after drug administration and persisting until 8 h. the deterioration in vigilance induced by amitriptyline was potentiated by concomitant diazepam.

The effects of transdermal scopolamine and four dose levels of oral scopolamine (0.15, 0.3, 0.6, and 1.2 mg) upon psychological performance

Four dose levels of oral scopolamine (0.15 mg, 0.3 mg, 0.6 mg, 1,2 mg), transdermal scopolamine, and placebo, were investigated for their effects upon a battery of psychological performance measures in normal subjects. Oral scopolamine produced significant linear dose-related decrements on tasks involving continuous attention, continuous performance, memory storage for new information, and on self-rated feelings of alertness and sociability. Transdermal scopolamine produced significant performance impairments on these same assessment measures. Resting heart rate levels were significantly reduced by all scopolamine conditions. Side effects (dry mouth, dizziness) were frequent following transdermal scopolamine and the higher oral dose conditions. The overall effects of the transdermal scopolamine patch were broadly equivalent to the effects of 0.8 mg oral scopolamine. This oral dose equivalence for transdermal scopolamine is higher than expected, and possible reasons for this are discussed.

Effects of transdermal scopolamine upon psychological test performance at sea

The effects of transdermal scopolamine upon objective psychological performance assessments and self reports of feeling states, were investigated with volunteer subjects at sea. Scopolamine and placebo patches were administered on consecutive days in a counterbalanced order. Psychological performance was assessed 24 h following each transdermal patch. Choice reaction time and code substitution performance levels were not significantly changed, but letter cancellation errors were significantly more frequent following transdermal scopolamine. Transdermal scopolamine caused significantly more reports of dry mouth. More subjects were also unable to undertake the performance tests following scopolamine than placebo, due to difficulties in focusing on the test materials. However despite deleterious side effects with some personnel, others responded positively to the scopolamine patch. As noted by other workers, responses to the transdermal scopolamine patch seem to be quite variable.

Interactions of benzodiazepines on psychomotor skills

Interactions of centrally active drugs are difficult to analyse in man due to methodological and ethical problems. Alcoholic and methylxanthine beverages are the most common centrally active agents that might modify the effects of benzodiazepines on performance. In sufficiently large doses ethanol enhances the effects of benzodiazepines, even those that are not metabolized by mixed function oxidases sensitive to blockade by ethanol. Consequently, the combined effect of ethanol and benzodiazepines may occur at the receptor level and/or result from altered binding of benzodiazepines to plasma proteins. Newer benzodiazepines may differ from the older in their interactions. Caffeine and theophylline counteract benzodiazepine effects on performance, resulting perhaps from the blockade of adenosine receptors which could be linked with the GABA-benzodiazepine receptor system. Central stimulants of the amphetamine type also counteract benzodiazepine effects in a somewhat selective way. New stimulant antidepressants rather counteract than increase benzodiazepine effects. Central antimuscarinics in combination with benzodiazepines are detrimental for memory. Specific benzodiazepine antagonists are effective also in man but without known clinical applications.