The action of sedatives on brain stem oculomotor systems in man

The effects of clonidine on the fear-inhibited light reflex

We have shown previously that pupil diameter increases and the amplitude of the pupillary light reflex is reduced when subjects are under threat of an aversive event (electric shock), and that light reflex amplitude correlates negatively with subjective anxiety. Furthermore, we have shown that the threat-induced reduction in light reflex amplitude is sensitive to the effect of the anxiolytic drug diazepam. We have suggested that the 'fear-inhibited light reflex' paradigm could be used as a laboratory model of human anxiety. In the present study, we examined whether a single oral dose (200 microg) of the sedative-sympatholytic drug clonidine would antagonize the effects of threat on the pupillary light reflex. Twelve healthy male volunteers participated in two sessions separated by seven days in which they ingested clonidine 200 mg or placebo in a double-blind, balanced, cross-over design. Light stimuli (0.43 mW/cm2, 200 msec) were generated by a green (peak wavelength 565 nm) light-emitting diode, and pupil diameter was monitored by computerized binocular infrared television pupillometry in the dark. The light reflex response was recorded during either the anticipation of a shock ('threat' blocks) or periods in which no shocks were anticipated ('safe' blocks). The shock was a single square wave current pulse (1.5 mA, 50 msec) applied to the median nerve at the end of the experiment. Following each 'threat' or 'safe' block, subjects rated their anxiety using visual analogue scales. Two-factor ANOVA (treatment x condition) showed that clonidine treatment antagonized both the threat-induced increase in pupil diameter and the threat-induced reduction in light reflex amplitude. These effects, however, were not threat-specific since clonidine also reduced pupil diameter and enhanced light reflex amplitude in the 'safe' condition. Clonidine also reduced subjective alertness but not subjective anxiety in the 'threat' condition. These findings suggest that the mutual antagonism between clonidine and threat is likely to reflect the opposite effects of the two variables on the central noradrenergic control of pupillary functions, rather than a specific anxiolytic effect.

Ritanserin facilitates anxiety in a simulated public-speaking paradigm

The effects of ritanserin, a 5-HT2A/2C (5-hydroxytryptamine) antagonist, have been investigated in simulated public speaking with healthy volunteers. The aim was to investigate the role of 5-HT in subjective experimental anxiety. There were three experimental groups each comprising four or five males and 11 females. Subjects received placebo, ritanserin 2.5 or 10 mg, p.o. They rated themselves using the Spielberger State-Trait Anxiety Inventory and visual analogue scales factored into anxiety, sedation and discontentment scores. Autonomic measures included skin conductance and heart rate. Subjects were told, 75 min after drug or placebo ingestion, without prior warning, to prepare a 4-min speech. Measures were taken before, during and after the speech. Ritanserin prolonged the anxiety induced by the procedure on the subjective ratings but had minimal effect on autonomic responses to the procedure. The result contrasts with an anxiolytic-like effect of ritanserin on aversively conditioned autonomic responses. The present finding is compatible with animal behavioural evidence that 5-HT has distinct and opposing roles in modulating conditioned and unconditioned anxiety.

Effects of clonidine and diazepam on the acoustic startle response and on its inhibition by 'prepulses' in man

This experiment examined the effects of two sedative/anxiolytic drugs, diazepam and clonidine, on the eyeblink component of the acoustic startle response in healthy volunteers. Twelve males (18-30 years), screened for normal hearing thresholds, participated in three sessions in which they received oral doses of placebo, diazepam 10mg and clonidine 200 microg according to a balanced double-blind protocol. Thirty-minute electromyographic recordings from the orbicularis oculi muscle of the right eye were carried out 120 min after ingestion of clonidine and 60 min after ingestion of diazepam. Subjects received 36 40-msec sound pulses (115 dB), separated by variable intervals (mean 25 sec); in 24 of the trials the pulse was preceded by a 40-msec prepulse (75 dB in 12 trials and 85 dB in 12 trials; prepulse-pulse interval, 120 msec). The amplitude of the startle response was significantly reduced both by diazepam (mean+/-SEM: -43.9+/-7.4%) and by clonidine (-75.7+/-4.7%). Under the placebo condition, the 75 and 85dB prepulses inhibited the startle response by 38.6+/-6.5 and 70.3+/-2.9%, respectively. Neither drug significantly altered the degree of prepulse inhibition. Both drugs reduced self-rated alertness; clonidine reduced systolic blood pressure and salivation. The results confirm the suppressant effect of clonidine on the startle response and show a qualitatively similar effect of diazepam; the results also demonstrate the insensitivity of prepulse inhibition of the startle response to doses of sedative drugs that are sufficient to attenuate the startle response itself.

The inhibition of the pupillary light reflex by the threat of an electric shock: a potential laboratory model of human anxiety

It has been shown that the eye-blink response evoked by an abrupt loud white noise ('acoustic startle') is potentiated when the subjects anticipate an aversive stimulus, e.g. an electric shock ('fear-potentiated startle'). It has been proposed that this paradigm may be a useful laboratory model of human anxiety. We examined whether the threat of an electric shock, as used in the fear-potentiated startle paradigm, would affect the pupillary light reflex, in 12 healthy volunteers. Light stimuli (0.32 mW/cm(2), 200 msec) were generated by a light-emitting diode, and pupil diameter was monitored by computerized binocular infrared television pupillometry in the dark. The light reflex was recorded during either the anticipation of a shock ('threat' blocks) or periods in which no shocks were anticipated ('safe' blocks). The shock consisted of a single square wave current pulse (1.5 mA, 50 msec) applied to the median nerve. At the end of each 'threat' or 'safe' block, subjects rated their anxiety using visual analogue scales. Two-factor analysis of variance (condition x block) showed that in the 'threat' condition there was a consistent increase in initial pupil diameter, a decrease in light reflex amplitude and an increase in alertness and anxiety ratings. These effects were observable before the subjects received any shock (a single stimulation of the median nerve). These results show that the anticipation of an electric shock can modify not only the startle reflex response but also the pupillary light reflex, suggesting that the inhibition of the light reflex by threat may be another suitable laboratory model of human anxiety.

The effect of chlorpromazine and benzhexol on memory and psychomotor function in healthy volunteers

Both antipsychotic and anticholinergic drugs have been implicated in the production of the memory deficits seen in schizophrenia. We compared the effects of chlorpromazine (50 mg) and benzhexol (5 mg) with placebo on a battery of tests of memory, psychomotor function and mood, in 12 healthy volunteers. Benzhexol, but not chlorpromazine, impaired both word recall and word recognition. Neither drug had an effect on long-term memory Both active compounds were associated with self-rated sedation, and chlorpromazine produced impairment in saccadic eye movements. This study supports the contention that sedation is unlikely to be the mechanism by which anticholinergic drugs exert their amnestic effect.

Controlled comparison of the effects and abrupt discontinuation of buspirone and lorazepam

1. The purpose of this study was to compare the effects and abrupt discontinuation of buspirone 15 or 20 mg tid and lorazepam 3 or 4 mg tid following 8 weeks of treatment. A total of 43 outpatients with generalized anxiety disorder were included in the study and 39 entered the withdrawal phase. 2. Clinical assessments were performed at baseline, 2, 4, 6 and 8 weeks (active phase) and after 9 and 10 weeks (withdrawal phase). These included the Hamilton anxiety scale, the visual analogue scale, the CHESS 84 (a check list for the evaluation of somatic symptoms) and the Lader tranquilizer withdrawal scale (translated in french). 3. Results show similar efficacy for lorazepam and buspirone during the active phase with a higher significant difference for buspirone on the CHESS 84 in relation with neurovegetatives symptoms: lorazepam D0 :16.30 +/- 3.14 D56: 5.10 +/- 0.93 (p < or = 0.01) buspirone D0 :18.82 +/- 3.4 D56: 4.73 +/- 1.18 (p < or = 0.001) No withdrawal phenomena was observed for both drugs using HAM-A lorazepam D63 :12.59 +/- 2.26 D70: 12.0 +/- 1.75 (p = ns) buspirone D63 :10.05 +/- 1.28 D70: 10.32 +/- 1.82 (p = ns) and the same significant difference using Lader scale: lorazepam D63 :4.44 +/- 0.89 D70: 6.96 +/- 1.28 (p < or = 0.05) buspirone D63 :2.95 +/- 0.66 D70: 4.15 +/- 0.92 (p < or = 0.05). 4. This study confirmed that buspirone was as effective as lorazepam at D56 in monitored outpatients with generalized anxiety disorder.(ABSTRACT TRUNCATED AT 250 WORDS)

Dissociations in the expression of the sedative effects of triazolam

Fifteen normal volunteers were administered 0.250, 0.375, and 0.500 mg of triazolam and placebo in a double-blind repeated measures cross-over design. Subjects demonstrated dose-dependent impairments in free recall, a test of explicit memory requiring awareness and reflection, and sedation as assessed by objective behavioral measures (the digit symbol substitution task) and subjective visual analogue scales. The sedative drug response did not account for the impairment in free recall. Differences in performance of the two tests of sedation indicated that the effect of this drug on reflective processes accounts for impairment in episodic memory and the inability to track the sedative effects of this drug at the higher doses tested in this study.

Critical flicker fusion threshold and anticholinergic effects of chronic antidepressant treatment in remitted depressives

The persistence of deficits in cognitive performance in major depressive patients taking maintenance antidepressant medication was assessed by examining groups of patients in clinical remission, stable on one of a range of tricyclics or selective serotonin re-uptake inhibitors (SSRIs) for at least 3 months, compared with controls. Measures of critical flicker fusion (CFF), choice reaction time (CRT), subjective sedation, and anticholinergic side-effect score were made. Tricyclic antidepressants (TCAs) produce a significant deficit in critical flicker fusion threshold compared both to controls and SSRIs. Similar effects were seen with choice reaction times which were significantly affected by age. Sedation scores were significantly higher with TCAs than SSRIs. Anticholinergic side effects were strongly related to CFF, less so to visual analogue sedating scales and not significantly to CRT. The effect measured by CFF is different from sedation, and may be related to the anticholinergic potency of the drug; it may be considered a drug-induced pseudodementia. This effect represents a risk factor for accidents during maintenance therapy and may impair work and leisure performance. The relative risk of weight gain with TCAs compared to SSRIs in women was 5.92 (95% CI 1.79-19.50).

Evaluating the effects of an alpha-2 adrenoceptor antagonist on erectile function in the human male. 2. The erectile response to erotic stimuli in men with erectile dysfunction, in relation to age and in comparison with normal volunteers

The effect of a new alpha-2 adrenoceptor antagonist on erectile function was assessed in 24 men with probable psychogenic erectile dysfunction. The drug was given in two dosages, together with placebo, by intravenous infusion in a balanced cross over design. Once plasma levels were established, erectile, subjective and haemodynamic responses to erotic fantasy and films were measured. Subjects were divided into two age groups, "Younger" (i.e. less than 45 years) and "Older" (greater than 45 years). There was a significant though modest increase in the duration of erectile response with the high dose of the drug, but only in the younger men. There were also drug effects on haemodynamic responses confined to the younger men, who showed markedly reduced responses during placebo administration when compared with the older dysfunctional men and with young "functional" volunteers. The findings raise the possibility that in younger men with psychogenic erectile failure, there is an inhibition of general arousal responses to erotic stimuli which is partially reversed by this drug. In the older men, the different pattern of response suggests that a) there may be a decline in response to the drug with age and b) other age-related factors are playing an important part in the aetiology of their erectile failure.

The subjective effects of low-dose propofol. A double-blind study to evaluate dimensions of sedation and consciousness with low-dose propofol

In this study the subjective effects (sedation and mood) of subanaesthetic doses of propofol were examined in 28 healthy male volunteers. A computer model was used to predict the infusion profiles necessary to obtain steady state propofol plasma concentrations of 0.3 microgram.ml-1, 0.6 microgram.ml-1, 0.9 microgram.ml-1. Objective measures of sedation from saccadic eye movement and choice reaction time gave significant dose responses at each level but a battery of psychometric tests failed to show dose-related subjective responses. Of particular note in the subjective data is the lack of a difference between groups or even of a consistent trend within the data. This suggests that a low concentration of propofol in plasma does not induce euphoria or a sense of well-being. The anecdotal evidence available for mood changes with propofol therefore remains unsubstantiated.

Pharmacokinetic study of yohimbine and its pharmacodynamic effects on salivary secretion in patients treated with tricyclic antidepressants

The pharmacokinetic parameters and the time course of the effect after acute oral administration of yohimbine on salivary secretion in patients treated with tricyclic antidepressants were investigated. Yohimbine (10 mg) increased both salivary outflow and plasma noradrenaline levels for 4 h. Pharmacokinetic parameters (t1/2, tmax, Cmax and AUCexp) and plasma concentrations of noradrenaline were higher in patients treated with tricyclic antidepressants than in controls. At this dose, yohimbine induced a relatively large number of side effects. A lower dose (4 mg) increased salivary secretion for 3 h without any side effects in patients treated with tricyclic antidepressants but not in healthy volunteers. These data describe an interaction between yohimbine and tricyclic antidepressants and thus show that a relatively low dose (4 mg) of yohimbine could be useful in the treatment of dry mouth due to tricyclic antidepressants.

Cimetidine does not influence the metabolism of the H1-receptor antagonist ebastine to its active metabolite carebastine

Ebastine is an H1-receptor antagonist with a relative lack of sedating properties. It is almost completely converted to carebastine, and it is this metabolite which is responsible for the antihistaminic effect. Twelve healthy subjects received a single 20 mg dose of ebastine on day 2 of a multiple oral dosing regimen of either cimetidine (400 mg three times daily and 800 mg in the evening on the day preceding ebastine administration and 400 mg four times daily on the 2 following days) or placebo in a randomised cross-over design. Significant plasma concentrations of ebastine were not detected after either treatment. The AUC of carebastine was not affected by cimetidine coadministration (4049 +/- 985 ng ml-1 h after cimetidine vs 3795 +/- 959 ng ml-1 h after placebo; 95% confidence interval of the difference: -412 to 919). Cimetidine coadministration did not induce any effect of ebastine on blood pressure and heart rate or cause sedation.

Alfentanil in daycase anaesthesia. Assessment of a single dose on the quality of anaesthesia and recovery

The effect of the addition of a single dose of 7 micrograms.kg-1 of alfentanil to a propofol/enflurane anaesthetic on the quality of anaesthesia and recovery was assessed. A total of 53 ASA grade 1 or 2 patients who underwent daycase dental surgery were allocated randomly to receive either alfentanil or saline. The study was blinded so that neither the anaesthetist nor the assessor was aware of which solution had been given. Patients in the alfentanil group took significantly longer to recommence spontaneous ventilation (p = 0.035). Both techniques provided good quality of anaesthesia. Postoperative morbidity was common (45% of patients), but there was no difference between the groups. The rate of recovery was similar in the two groups and no patient required hospital admission after the final assessment at 3 h. Drowsiness was only mild to moderate in both groups at 24 h. A single dose of alfentanil can be administered safely as part of a daycase anaesthetic without increasing morbidity, although there appears to be little advantage in doing so.

Effects of ipsapirone and cannabidiol on human experimental anxiety

The effects of ipsapirone and cannabidiol (CBD) on healthy volunteers submitted to a simulated public speaking (SPS) test were compared with those of the anxiolytic benzodiazepine diazepam and placebo. Four independent groups of 10 subjects received, under a double-blind design, placebo or one of the following drugs: CBD (300 mg), diazepam (10 mg) or ipsapirone (5 mg). Subjective anxiety was evaluated through the Visual Analogue Mood Scale (VAMS) and the State-trait Anxiety Inventory (STAI). The VAMS anxiety factor showed that ipsapirone attenuated SPS-induced anxiety while CBD decreased anxiety after the SPS test. Diazepam, on the other hand, was anxiolytic before and after the SPS test, but had no effect on the increase in anxiety induced by the speech test. Only ipsapirone attenuated the increase in systolic blood pressure induced by the test. Significant sedative effects were only observed with diazepam. The results suggest that ipsapirone and CBD have anxiolytic properties in human volunteers submitted to a stressful situation.

Specific memory and sedative effects of the benzodiazepine triazolam

Fifteen normal volunteers were administered placebo, 0.250, 0.375 and 0.500 mg of triazolam in a double- blind cross-over design. Triazolam induced robust dose-dependent impairments in explicit memory of information presented after drug administration. Subjects were unaware of their memory deficit (an impairment in meta-cognition). In contrast, memory for information presented prior to the administration of triazolam was facilitated following the administration of low doses of triazolam. Implicit memory and access to knowledge memory was unaltered by this benzodiazepine. An analysis of these results controlling for concurrent sedation as measured subjectively, through the use of self rating scales and objectively, based upon psychomotor performance, demonstrated that the amnestic effects of triazolam are largely independent of sedative effects. The pattern of memory changes induced by benzodiazepines, such as triazolam, is similar to the memory inpairment expressed in amnestic patients but unlike the pattern of impaired memory evident in dementia such as Alzheimer's disease.

Benzodiazepine pharmacodynamics: utility of eye movement measures

The utility of several measures of saccadic and smooth pursuit eye movements as benzodiazepine pharmacodynamic measures was explored in 24 psychiatrically and medically health control subjects. Measures of sedation and memory impairment were also included. Subjects received four logarithmically increasing doses of intravenous diazepam at 15-min intervals on 1 day resulting in monotonically increasing plasma diazepam levels, and placebo on another day in random order 1 week apart. Measures were collected twice at baseline, once after each dose of diazepam/placebo and twice more, 15 and 30 min after the last dose. Peak saccadic velocity and smooth pursuit gain showed the greatest overall and dose-dependent drug effect among eye movement measures. Although effect sizes at the highest dose for memory impairment and self-rated sedation were comparable to these two measures, reliability (i.e., placebo-day fluctuation) with these measures was considerably poorer. Log-linear pharmacodynamic modeling was used to calculate the effective dose (ED30) or concentration (EC30) required to reduce saccadic velocity or pursuit gain by 30%. Almost all (23/24) subjects had linear and easily interpretable plots for saccadic velocity, while a majority (19/24) of subjects had interpretable plots for smooth pursuit gain. The distribution of ED30 and EC30 values showed a wide range of sensitivities to diazepam. These findings suggest that saccadic velocity and smooth pursuit gain are sensitive, reliable, quantitative benzodiazepine pharmacodynamic measures.

Carbamazepine and lamotrigine in healthy volunteers: relevance to early tolerance and clinical trial dosage

This study was conducted to examine the effects of acute doses of lamotrigine (LTG) and carbamazepine (CBZ) in healthy subjects and determine whether the low tendency to impairment with LTG observed in animals applied to humans. Twelve healthy men participated in a placebo-controlled, balanced, double-blind comparison of the drugs on a series of psychomotor, autonomic, sensory, and subjective variables. Variables were analyzed by analysis of variance, and p < 0.05 was considered significant. Adaptive tracking and body sway were impaired by CBZ 600 mg. CBZ 400 and 600 mg impaired smooth pursuit eye movements and also reduced mean peak saccadic velocity. No differences from placebo occurred after LTG. CBZ 600 mg increased heart rate (HR), but no drug-related changes were noted in pupil size, salivary secretion, visual near point, or subjective effects. During the controlled study, mean plasma CBZ concentrations at 2 and 6.5 h after the 600-mg dose were 5.28 and 5.36 micrograms/ml; after LTG 300 mg, they were 3.16 and 3.00 micrograms/ml. Increased CBZ saliva concentrations were significantly associated (p < 0.01) with impaired adaptive tracking, smooth and saccadic eye movements and increased HR, and plasma concentrations were associated with impaired eye movements and body sway.

Neuroendocrine responses to challenge with dl-fenfluramine and aggression in disruptive behavior disorders of children and adolescents

Prolactin (PRL) and cortisol (CORT) responses to a single oral administration (1.0 mg/kg) of the indirect serotonin agonist dl-fenfluramine were assessed in unmedicated prepubertal and adolescent males with disruptive behavior disorders (DBD). Neuroendocrine responses were correlated with scores on aggression rating scales in prepubertal and adolescent DBD patients and compared with those of matched adolescent normal control subjects. Net dl-fenfluramine-induced PRL and CORT release was not correlated with aggression rating scores in prepubertal and adolescent DBD patients and did not differ significantly between adolescent DBD patients and normal control subjects. Although the present study does not demonstrate a serotonergic abnormality in aggression or DBD, this may be more a reflection of limitations of the neuroendocrine challenge test procedures or the methods used than evidence that serotonergic function in the central nervous system is normal in aggression.

The effect of neuroleptics on cognitive and psychomotor function. A preliminary study in healthy volunteers

The effects of haloperidol (1 mg), benzhexol (5 mg), diazepam (10 mg) and caffeine (400 mg) on subjective and objective measures of cognitive and psychomotor function were compared with placebo in 20 healthy volunteers. While both diazepam and benzhexol were associated with highly significant impairments in subjective altertness, critical flicker fusion threshold and choice reaction time (CRT), haloperidol could not be distinguished from placebo in most tests but was actually associated with an apparent improvement in CRT (in males) and simple visual reaction time. The perceptual maze test detected impairment by benzhexol on processing speed but was not sensitive to any other drug effects. Multiple-dose studies are required to establish if there is a true activating effect of haloperidol using a test of sustained attention. No effect of Eysenck personality subtype or life events on baseline or drug response data was detected.

Test-retest reliability of the prolactin and cortisol responses to D,L-fenfluramine challenge in disruptive behavior disorders

We examined the intraindividual stability of plasma prolactin (PRL) and cortisol responses to D,L-fenfluramine challenges (1.0 mg/kg, p.o.), at a 1-week interval, in boys with disruptive behavior disorders. Two acute administrations of fenfluramine produced consistent and predictable effects on net prolactin responses (peak delta PRL, area under the curve delta PRL), but variable and unpredictable effects on net cortisol responses. The time course and magnitude of fenfluramine blood levels, not nor-fenfluramine, paralleled net PRL responses to fenfluramine. These data indicate that the PRL response to fenfluramine shows continuity within individuals over the course of 1 week, providing a reliable index to reflect the overall function of the serotonin system in the limbic-hypothalamus.

Pharmacokinetics and safety of lamotrigine (Lamictal) in patients with epilepsy

In a double-blind parallel study, patients with epilepsy on stable regimen of antiepileptic drugs (AEDs) were given lamotrigine (8 pts) or placebo (3 pts). Patients were sequentially dosed with 100, 200 and 300 mg/day given as a b.i.d. regimen. After steady state was achieved, timed plasma lamotrigine levels were obtained post dose. No medical, psychogenic, neurologic, or hematologic changes were observed and no subjective effects were detected as a result of treatment with lamotrigine. No changes in heart rhythm or blood pressure were observed related to lamotrigine. Pharmacokinetic parameters were calculated using 1-compartment and non-compartment models. The results were similar using both models. Area under the plasma concentration vs. time curves increased linearly with dose. Mean half life (13.5 h), volume of distribution (1.36 l/kg) and clearance (1.27 ml/min/kg) were similar to previously reported results and did not change with increasing dose. These findings indicate that lamotrigine pharmacokinetics can be described by the 1-compartment model, has linear kinetics, and does not induce its own metabolism in patients on concomitant AEDs.

A comparison of the central nervous system effects of haloperidol, chlorpromazine and sulpiride in normal volunteers

1. Twelve healthy male volunteers participated in four experimental occasions during each of which they were dosed with one of the following anti-psychotic drugs: chlorpromazine (50 mg), haloperidol (3 mg), sulpiride (400 mg) and placebo. Drugs were allocated to subjects in a double-blind, crossover fashion. 2. The subject's mood state, psychometric performance and electroencephalogram (EEG) were assessed pre-dose, and at 2, 4, 6, 8, 24 and 48 h post-dose. Mood states were assessed using 16 visual analogue scales and psychomotor performance was measured using the following tests: elapsed time estimation, tapping rate, choice reaction times, a rapid information processing task, flash fusion threshold, a manipulative motor task, digit span, body sway and tremor. 3. Chlorpromazine and haloperidol significantly reduced subjective ratings of 'alertness' and 'contentedness', and haloperidol significantly reduced feelings of 'calmness'. Sulpiride did not significantly affect any of the visual analogue scales. 4. All three anti-psychotic drugs had similar EEG effects with peak effect 2 to 4 h postdose. The profile was characterised by an increase in the proportion of slow wave activity (delta and theta) as well as decreased alpha (8-14 Hz) and faster (beta) wave activity. 5. Chlorpromazine reduced tapping rate and increased choice reaction movement times. Haloperidol reduced the flash fusion threshold frequency at 6 h post-dose. Sulpiride prolonged the duration of the manipulative motor task, particularly at 48 h post-dose. 6. All three anti-psychotic drugs impaired performance on the rapid information processing task. Chlorpromazine significantly reduced the number of correct letter pair identifications at 2, 4 and 6 h post-dose, haloperidol at 4, 6, 8, 24 and 48 h post-dose, and sulpiride at 24 h post-dose.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of lithium carbonate on healthy volunteers: mood stabilization?

A 2-month lithium-placebo double-blind cross-over study was carried out with 17 healthy volunteers. Their mood was self-rated: twice daily (AM, PM) with the Visual Analogue Mood Scale (VAMS); weekly with the analogue scales for subjective states and body symptoms; and three times (basal and at the end of each treatment period) with the Profile of Mood States (POMS). Memory and reaction time were also assessed, but did not show any change. The mean VAMS score decreased during lithium treatment, but the mean mood variability, a measure of the mean successive differences between consecutive mood ratings (delta squared), did not change significantly. There was a tendency toward decreased mood variability on lithium, both during the full 1-month treatment period and in the last week of treatment, when all volunteers had a lithium serum level ranging from 0.6 to 1.0 mEq/liter. The lower mean VAMS scores on lithium could be attributed to lithium-induced dysphoric mood as recorded on the analogue scales and POMS. However, very large inter- and intraindividual differences in response to lithium were observed. Actually, lithium even had an opposite effect on some volunteers' mood. The data and problems involved with assessment of mood and its changes are discussed.

Evaluation and comparison of the interaction between alcohol and moclobemide or clomipramine in healthy subjects

The interaction of clomipramine and moclobemide with alcohol was compared in a double blind parallel groups study in 24 healthy volunteers. Moclobemide was given at the highest recommended therapeutic dose (200 mg t.i.d.) and clomipramine in a subtherapeutic dose (25 mg b.i.d.) because of its poor tolerance in healthy subjects. Psychometric evaluations were performed during a placebo run-in phase; after a 5-day treatment period; assessments were made before, and again 1 h and 4 h after alcohol ingestion. Alcohol doses were pre-determined for each subject in order to produce a blood alcohol concentration of 0.6 g/l 1 h after alcohol intake and this individual alcohol dose was given on test days. The day before alcohol intake tests for autonomic functions were made to assess the anticholinergic effects of the drugs. Alcohol significantly increased body sway, decreased critical flicker fusion frequency, prolonged choice reaction time, impaired copying skills, impaired memory and increased the subjective feelings of satisfaction and tension. Drugs increased the effect of alcohol on body sway and this was essentially due to clomipramine. Clomipramine both without and with alcohol increased body sway, prolonged choice reaction time more than did moclobemide. Clomipramine seemed to diminish alcohol-induced memory impairment in one of the memory tests used. Subjects taking clomipramine had significantly more adverse effects after alcohol ingestion than did subjects of the moclobemide group. In contrast to moclobemide, clomipramine produced a moderate but significant drop in standing systolic blood pressure and a clear inhibition of salivary excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Psychomotor effects of ketorolac in comparison with buprenorphine and diclofenac

1. Ketorolac is an investigational non-opioid analgesic. Buprenorphine, an opioid compound and diclofenac, a non-steroidal anti-inflammatory, are analgesics used in clinical practise. 2. The psychomotor effects of ketorolac (30 mg), buprenorphine (0.3 mg), diclofenac (50 mg) and placebo all administered i.m., were examined in 12 healthy male volunteers (age 19-38 years), up to 8 h post-dose. 3. Creatine phosphokinase (CPK) was measured up to 24 h post-dose, providing an indication of local tissue damage following injection. 4. Buprenorphine caused significant psychomotor impairment in seven out of eight psychomotor tests. The effects consistently peaked 4 h post-dose and were still apparent in many cases 8 h post-dose. These psychomotor effects were supported by marked symptoms in all volunteers. 5. Ketorolac and diclofenac had no clinically significant effects on psychomotor tests and only minimal symptoms were reported. 6. Diclofenac caused a marked increased in CPK (mean Cmax 298 iu l-1) compared with ketorolac (mean Cmax 70 iu l-1) and buprenorphine (mean Cmax 68 iu l-1). 7. These results suggest that ketorolac and diclofenac are suitable for administration following day case surgery.

Clinical applications of visual analogue scales: a critical review

Visual Analogue Scales (VAS) provide a simple technique for measuring subjective experience. They have been established as valid and reliable in a range of clinical and research applications, although there is also evidence of increased error and decreased sensitivity when used with some subject groups. Decisions concerned with the choice of scoring interval, experimental design, and statistical analysis for VAS have in some instances been based on convention, assumption and convenience, highlighting the need for more comprehensive assessment of individual scales if this versatile and sensitive measurement technique is to be used to full advantage.

Clinical pharmacology of sibutramine hydrochloride (BTS 54524), a new antidepressant, in healthy volunteers

The cardiovascular, anticholinergic and central effects of single doses of 30, 45 and 60 mg of sibutramine hydrochloride (BTS 54524), a new potential antidepressant, were compared with amitriptyline (50 mg) and placebo given at weekly intervals in a randomised design to six healthy male volunteers. Sibutramine was associated with increases in both supine heart rate and systolic blood pressure at 1, 2 and 6 h after 60 mg (P less than 0.05). Amitriptyline caused a significant 50-60% decrease in salivation compared with placebo at 2 and 6 h but there were no changes with sibutramine. No significant changes in pupil size were detected with either drug. Visual analogue rating scales (VARS) revealed significant drowsiness with amitriptyline but neither sedative nor stimulant effects with sibutramine. Impairments of simple auditory and visual reaction times, visual two-choice reaction time, finger tapping and trail making, measured using an automated test battery, occurred with amitriptyline compared with sibutramine. If sibutramine proves to be an effective antidepressant it should be devoid of anticholinergic or central depressant effects. Chronic dosage studies are indicated to evaluate the clinical significance of its cardiovascular effects.

Antagonism of flunitrazepam-induced sedative effects by flumazenil in patients after surgery under general anaesthesia. A double-blind placebo-controlled investigation of efficacy and safety

This study aimed to assess the efficacy and safety of flumazenil and a placebo in reversing the residual effects of flunitrazepam used to induce anaesthesia for elective laparoscopy in 49 female patients aged 16 to 52 years. In contrast to the placebo, flumazenil gave reductions in amnesia, sedation score, mood rating for mental sedation and physical sedation, and time taken to complete a psychomotor performance test which lasted throughout the study. There were no significant changes in pulse rate, respiration rate or blood pressure, and no unwanted effects were attributed to flumazenil.

Diazepam and memory: evidence for spared memory function

The effects of diazepam on several tests of memory were investigated in a double-blind study of 24 healthy young adults. Following a single oral administration of 0.3 mg/kg diazepam or placebo, subjects in the diazepam group showed marked impairment in immediate free recall of words as compared to placebo control subjects. However, diazepam-treated subjects demonstrated performance benefits from prior exposure to the same words on tests of memory priming using word completion and category-generation tasks. The two types of memory tests differ in their demand for conscious recollection. Tests of free recall have explicit (declarative) memory demands whereas the priming test places only implicit (procedural) demands upon memory. The results demonstrate that diazepam spares some forms of memory as does amnesia induced by neurological impairment.

Antagonism of diazepam-induced sedative effects by Ro15-1788 in patients after surgery under lumbar epidural block. A double-blind placebo-controlled investigation of efficacy and safety

The aim of this study was to assess the efficacy of Ro15-1788 and a placebo in reversing diazepam-induced effects after surgery under epidural block, and to evaluate the local tolerance and general safety of Ro15-1788. Fifty-seven patients were sedated with diazepam for surgery under epidural anaesthesia. Antagonism of diazepam-induced effects by Ro15-1788 was investigated postoperatively in a double-blind placebo-controlled trial. The patient's subjective assessment of mood rating, an objective test of performance, a test for amnesia, and vital signs were recorded for up to 300 min after administration of the trial drug. No significant differences between the two groups were observed for mood rating, amnesia, or vital signs. The Ro15-1788 group showed a significant improvement in the performance test up to 120 min after administration of the drug. There was no evidence of reaction at the injection site.

Effects of desipramine and total sleep deprivation on hormonal levels of healthy subjects

Plasma prolactin (PRL) and growth hormone (GH) were serially measured over a 5-hour morning period in healthy subjects who twice received a single oral dose of 100 mg desipramine (DMI). The study was carried out both after a regular night of sleep and after 1 night of total sleep deprivation. Clinical studies have suggested that sleep deprivation could potentiate the therapeutic effects of antidepressants, and there were reports on DMI stimulation of GH. The basal PRL levels decreased after sleep deprivation, but subsequently increased after DMI, whereas the same dose of DMI did not affect PRL in the absence of after DMI, whereas the same dose of DMI did not affect PRL in the absence of sleep deprivation. The GH levels increased substantially (8- to 10-fold) after DMI in both experimental conditions. Sleep deprivation neither changed GH basal levels nor potentiated the DMI-induced GH increase.

Benzodiazepines as oral premedication. A comparison between oxazepam, flunitrazepam and placebo

Oxazepam 25 mg, flunitrazepam 1 mg and placebo were compared as oral premedication in 602 gynecological patients in a double-blind randomised parallel study. In 251 patients undergoing major surgery the same drug was also given as a hypnotic the night before the operation. Both active drugs shortened the sleep-onset time, decreased the number of spontaneous awakenings at night and improved the quality of sleep when compared to placebo. The active drugs were significantly better than placebo as premedication when assessed by both the patients and the anesthesiologist. In 351 patients admitted for day-case minor surgery with no previous night medication, flunitrazepam was significantly better than placebo as premedication when assessed by both the patients and the anesthesiologist, while oxazepam was only better than placebo when judged by the anesthesiologist, not by the patients.

The effects of acrivastine (BW825C), diphenhydramine and terfenadine in combination with alcohol on human CNS performance

Two studies were performed to measure the effects of acrivastine (BW825C), an antihistamine, in combination with alcohol on the central nervous system. In one study acrivastine 8 mg, diphenhydramine 50 mg and alcohol 32 ml were administered alone and in combination and compared with placebo. In a second study terfenadine 60 and 120 mg and acrivastine 4 and 8 mg combined with alcohol 32 ml were compared with placebo and alcohol alone. Each study was a double-blind, randomised cross-over design using twelve healthy volunteers. Adaptive tracking, reaction time, body sway, eye movements and subjective effects were measured at intervals after treatments. Acrivastine 8 mg alone did not affect any of these measures in contrast with diphenhydramine. Acrivastine in combination with alcohol caused significantly more impairment of some of the tests than placebo or alcohol alone, but significantly less than diphenhydramine/alcohol, which also affected more tests. In the second study no significant differences were seen between the effects of alcohol alone and combinations of either terfenadine or acrivastine with alcohol. It was concluded that acrivastine 8 mg alone did not impair CNS performance in the tests used. In combination with alcohol significant impairment was seen, but this was less pronounced than after diphenhydramine/alcohol. The second study failed to demonstrate differences between drug/alcohol combinations and alcohol alone confirming that the effect of acrivastine in combination with alcohol is small.

Comparison of the clinical hypnotic effects of zopiclone and triazolam

In a double blind crossover therapeutic trial the hypnotic effect of Zopiclone 7.5 mg and Triazolam 0.5 mg given orally at bedtime for 7 consecutive days have been compared. 5 of the items in Spiegel's questionnaire and 12 of the 18 items in Norris' visual analogue scale were significantly more improved by Zopiclone than by Triazolam. Both drugs caused few side-effects.

Effect of chlorimipramine and maprotiline on experimental anxiety in humans

In order to assess the role played by serotonin (5-HT) and noradrenaline in anxiety, four groups of healthy volunteers were given 25 mg of the selective inhibitor of 5-HT uptake chlorimipramine, 50 mg of the selective inhibitor of noradrenaline uptake maprotiline, 1 mg of the benzodiazepine anxiolytic lorazepam or placebo, and submitted to a simulated public speaking (SPS) test, consisting of speaking in front of a videocamera. Subjective anxiety was evaluated by the visual analog mood scale (VAMS) of Norris as well as by the state-trait anxiety inventory (STAI) of Spielberger. Chlorimipramine enhanced SPS-induced anxiety, whereas maprotiline and lorazepam reduced anxiety during as well as outside the test period. Mental and physical sedation (VAMS) were increased by either maprotiline or lorazepam. In a scale of bodily symptoms, chlorimipramine tended to increase muscle tension, agitation and palpitation, whereas maprotiline caused lethargy. The rise in blood pressure induced by the SPS procedure outlasted the period of stress in the group treated with chlorimipramine. In contrast, the SPS-induced increase in heart rate was enhanced by lorazepam. Chlor imipramine and maprotiline reduced salivation to the same extent. Pupillary diameter, however, was significantly increased by chlorimipramine alone. It may be tentatively sug gested that the proanxiogenic effect of chlorimipramine is related to changes in central 5-HT neurotransmission while the anxiolytic effect of maprotiline is associated with alteration of noradrenergic mechanisms. Increased peripheral sympathetic tone may also contribute to the proanxiety action of chlorimipramine.

Diazepam, behavior, and aging: increased sensitivity or lower baseline performance?

Cognitive performance, psychomotor skills, and subjective reactions to diazepam and placebo were compared in 12 healthy, well-educated subjects in three age groups: 19-28, 40-45, and 61-73 years old. With only minor exceptions, the changes in performance caused by diazepam and age differences were statistically additive and noninteracting. Diazepam did not act synergistically in older individuals; the decrements in performance were about the same in all age groups. Baseline performance decreased with increasing age; middle-aged subjects performed more like older than younger subjects. A variety of tasks exhibited similar effects of aging and diazepam, i.e., when performance declined with increasing age, it was also reduced by diazepam.

Hormonal and behavioral effects associated with intravenous L-tryptophan administration

Doses of 5.0, 7.5 and 10.0 g L-tryptophan, the amino acid precursor of serotonin, or saline alone were administered by IV infusion to a group of 11 healthy male subjects, and both hormonal and behavioral responses were monitored. Significant increases were observed in plasma concentrations of growth hormone and prolactin after all three doses of L-tryptophan, but not after saline infusion. No alterations in cortisol or thryotropin were noted at any level. Examination of behavioral effects of L-tryptophan revealed a dose-dependent impairment in performance on the symbol copying test. In addition, L-tryptophan produced significant effects on mental and physical sedation, but did not alter subjective ratings of tranquilization. In agreement with some prior reports, these observations support the ability of L-tryptophan, when administered IV in high doses, to produce pronounced effects on the central nervous system in humans, and suggest the potential utility of this paradigm as a neuroendocrine challenge test.

Lamotrigine (BW430C), a potential anticonvulsant. Effects on the central nervous system in comparison with phenytoin and diazepam

Twelve healthy male volunteers received phenytoin 0.5 and 1 g, lamotrigine (a new anticonvulsant) 120 and 240 mg, diazepam 10 mg and placebo orally in a double-blind, cross-over, randomized trial. Maximum drug concentrations at 4 h, measured in plasma were 11.5 +/- 2.2 micrograms ml-1 for phenytoin and 2.7 +/- 0.4 micrograms ml-1 for lamotrigine. These levels were in the therapeutic range for phenytoin and the putative therapeutic range for lamotrigine. Side effects after diazepam (mainly sedation) and phenytoin (mainly unsteadiness) differed markedly from lamotrigine which produced no important side effects. Subjective effects as measured by visual analogue scales were caused by phenytoin and diazepam but not by lamotrigine. Diazepam impaired eye movements, adaptive tracking and body sway. Phenytoin impaired adaptive tracking, increased body sway and impaired smooth pursuit eye movement. Lamotrigine produced only a possible slight increase in body sway. There were significant correlations between performance and saliva levels of phenytoin and diazepam. It was concluded that the tests used were suitable for monitoring CNS effects of anticonvulsants and that lamotrigine possibly could have a more favourable CNS side effect profile than phenytoin.

Caffeine and diazepam: separate and combined effects on mood, memory, and psychomotor performance

The effects of caffeine and diazepam on several mood, cognitive, learning, memory, and psychomotor tasks were investigated in a double-blind study of 108 young healthy adults who were randomly assigned to nine treatments; oral administration of caffeine (0, 3 and 6 mg/kg), diazepam (0, 0.15, and 0.30 mg/kg) and their combinations. Subjects completed a battery of tasks once before and twice after administration of the drugs. Caffeine alone showed no effects on cognitive, learning, and memory performance, but impaired fine motor coordination and increased anxiety and tenseness. Diazepam alone produced sedation, lowered other ratings of subjective moods, and impaired cognitive, learning, and memory performance. The two drugs did not antagonize the effects of each other, except in the symbol cancellation task.

Oculomotor function in Wernicke-Korsakoff's syndrome: I. Saccadic eye movements

Saccadic eye movements from three patients diagnosed as having Korsakoff's syndrome and one patient who had suffered the acute Wernicke stage of the disorder were examined for changes in saccadic characteristics. The three Korsakoff patients showed increased saccadic latencies; two of the three also had reduced saccadic peak velocities and increased saccadic durations. A higher than expected incidence of hypometric saccades was also found in all four patients; saccadic intrusions were recorded in two Korsakoff patients. These abnormal oculomotor responses were found 2-7 years after the onset of the Korsakoff's syndrome and are consistent with the cerebellar and frontal lobe dysfunction reported in this patient group.

Oculomotor function in Wernicke-Korsakoff's syndrome: II. Smooth pursuit eye movements

Smooth pursuit eye movements were studied in three patients with alcoholic Korsakoff's syndrome, one with Wernicke's encephalopathy, and an age-matched control. Horizontal smooth pursuit eye movements were abnormal in all patients: peak eye velocity and the ability to sustain smooth eye velocity were reduced. Also, smooth pursuit gain began to decrease at relatively low target velocities (i.e., 8-10 degrees). These data demonstrate a severe disturbance in smooth pursuit function long after the clinically apparent oculomotor abnormalities have passed.

Comparison of the effects of ranitidine, cimetidine and thioridazine on psychomotor functions in healthy volunteers

Eight healthy male volunteers participated in four experimental sessions in which they ingested one of the following drugs: ranitidine hydrochloride (150 mg), cimetidine hydrochloride (400 mg), thioridazine hydrochloride (50 mg), placebo (lactose). Drugs were allocated to subjects and sessions in a double-blind fashion, according to a balanced cross-over design. The subjects' mood state and psychomotor performance were assessed 1 and 3 h after drug taking. Mood state was measured using a battery of visual analogue scales, and psychomotor performance using pencil-and-paper tests, critical flicker fusion frequency, wire-maze tracing and tapping. Ranitidine and cimetidine had no significant effect on subjectively rated alertness, whereas thioridazine caused a significant decrease in alertness. Ranitidine and cimetidine had no significant effect on performance on the pencil-and-paper tests (digit cancellation, digit symbol substitution, symbol copying), whereas thioridazine caused a significant decrement on these tests. Ranitidine and cimetidine had no significant effect on critical flicker fusion frequency, wire-maze tracing, and tapping rate. Thioridazine caused a significant impairment of psychomotor performance as evidenced by all the instrumental tests. It is concluded that, in contrast to thioridazine and similarly to cimetidine, ranitidine has little effect on subjectively rated alertness and psychomotor performance in healthy volunteers.

Behavioral effects of oral versus intravenous administration of diazepam

The behavioral effects of oral versus intravenous administration of diazepam were studied in 50 volunteers using a battery of memory, cognitive, mood and psychomotor tests repeated over a 4.5 hr period. Subjects received diazepam 0.2 mg/kg or placebo as capsules, commercial tablets or intravenous solution in a randomized double blind manner. While a quick onset of effects occurred with intravenous administration followed by the capsule and tablet oral administrations in that order, the recovery rate was similar for the 3 methods of administration. Contrary to many claims in the literature the effects of oral administration were substantial. Behavioral impairment was directly related to the magnitude of the memory component of the task. On many of the tasks the pattern of diazepam impairment was one of delayed improvement of performance, a pattern which would only be apparent with repeated testing. Subjects who received diazepam showed a paradoxical enhancement of recall for material learned before the drug.

Ventilatory and mental effects of alfentanil and fentanyl

Forty healthy, young volunteers received intravenously, in a double-blind and random fashion, 7.5 or 15 micrograms/kg of alfentanil, 1.5 or 3 micrograms/kg of fentanyl, or saline. The ventilatory response to CO2 was measured before and at 4, 20, 30, 50, 80, and 120 min post-treatment. Mental and psychomotor functions were measured before and at 10, 40, 100, 130, and 180 min post-treatment. Low and high-dose fentanyl caused significant respiratory depression up to 30 and 80 min post-treatment, respectively, while there was no depression with low-dose alfentanil and only at 4 min with high-dose alfentanil. The fentanyl to alfentanil potency ratio for respiratory depression was 13:1. High-dose fentanyl caused more intense and prolonged mental effects than other treatments. Neither drug affected learning or recall, although high-dose fentanyl impaired motor activity. Nausea and vomiting rates were similar between high-dose alfentanil and low-dose fentanyl.

Dose-response analysis of the behavioral effects of diazepam: II. Psychomotor performance, cognition and mood

The psychomotor, cognitive, and mood effects of orally administered diazepam and placebo were measured over approximately equal to 3.5 h. A total of 120 volunteers were assigned to 12 groups of 10 each, representing the combination of four treatments (placebo, 0.1, 0.2, and 0.3 mg/kg diazepam) and three testing sessions (7 AM, 1 PM, and 7 PM). A variety of cognitive tasks, tapping and postural stability tests, and a mood evaluation scale were used. Psychomotor and cognitive functions showed consistent dose-response effects, while for subjective evaluations, the only effect of dose level was in the duration of sedation. The pattern of impairment of cognitive functions suggests that the drug affects speed rather than accuracy, and it primarily blocks acquisition of new information or skills. Use of repeated testing may therefore be necessary to detect subtle drug effects. Subjects reported no tranquilization , which suggests that the anxiolytic action of the drug cannot be studied in healthy volunteers. There was no circadian influence on the actions of the drug.

A comparison of methods for assessing the sedative effects of diphenhydramine on skills related to car driving

A double blind cross-over study was performed to compare the sensitivity of "oof road" driving with that of laboratory tests of driving-related skills to drug induced sedation. Twelve experienced drivers (6 M, 6 F) received single oral doses of the H1-antagonist diphenhydramine 25, 50 and 100 mg and placebo. Each treatment was administered on 2 separate occasions, once in the driving school when real driving skills were assessed and again in the laboratory when performance of an adaptive tracking task, body sway and visual reaction were measured. On all occasions subjects assessed their own performance and alertness/sedation using visual analogue scales. Data were subjected to analysis of variance and differences assessed by Newman Keul's test. Diphenhydramine failed to impair driving performance at any dose while all doses produced significant changes in each of the 3 laboratory tests. Subjects rated themselves sedated after all 3 doses of active drug in the laboratory but only after the 100 mg dose in the driving school. Tests performed in the psychopharmacology laboratory appear to be more sensitive to the sedative effects of diphenhydramine than tests of "off road" driving. The implications are discussed.