A comparison of the effect of imipramine, nomifensine, and placebo on the psychomotor performance of normal males

Blockade of Catecholamine Reuptake in the Prelimbic Cortex Decreases Top-down Attentional Control in Response to Novel, but Not Familiar Appetitive Distracters, within a Timing Paradigm

Emotionally charged distracters delay timing behavior. Increasing catecholamine levels within the prelimbic cortex has beneficial effects on timing by decreasing the delay after aversive distracters. We examined whether increasing catecholamine levels within the prelimbic cortex also protects against the deleterious timing delays caused by novel distracters or by familiar appetitive distracters. Rats were trained in a peak-interval procedure and tested in trials with either a novel (unreinforced) distracter, a familiar appetitive (food-reinforced) distracter, or no distracter after being locally infused within the prelimbic cortex with catecholamine reuptake blocker nomifensine. Prelimbic infusion of nomifensine did not alter timing accuracy and precision. However, it increased the delay caused by novel distracters in an inverted-U dose-dependent manner, while being ineffective for appetitive distracters. Together with previous data, these results suggest that catecholaminergic modulation of prelimbic top-down attentional control of interval timing varies with distracter’s valence: prelimbic catecholamines increase attentional control when presented with familiar aversive distracters, have no effect on familiar neutral or familiar appetitive distracters, and decrease it when presented with novel distracters. These findings detail complex interactions between catecholaminergic modulation of attention to timing and nontemporal properties of stimuli, which should be considered when developing therapeutic methods for attentional or affective disorders.

Serotonin, noradrenaline and cognitive function: a preliminary investigation of the acute pharmacodynamic effects of a serotonin versus a serotonin and noradrenaline reuptake inhibitor

Comparisons of the behavioural side-effect profiles of antidepressants that inhibit either serotonin or both serotonin and noradrenaline reuptake, may reveal differences in cognitive and psychomotor functions, which may be attributed to their relative pharmacological selectivity for potentiating monoamine neurotransmission in the central nervous system. The aim of the present study was to determine the acute pharmacodynamic effects of citalopram and venlafaxine, on cognitive and psychomotor performance. Nine healthy male volunteers received a single clinical dose of citalopram, venlafaxine or amitriptyline (positive control) in a double-blind placebo-controlled design. Cognitive and psychomotor tests and a subjective measure of sedation were examined before and 1, 2 and 4 hours after drug administration. Citalopram improved psychomotor responses to sensory stimuli and sustained attention, with significant decreases in movement times of the choice reaction time test and an increase in critical flicker fusion threshold. Venlafaxine did not affect performances on any of the cognitive or psychomotor tests examined. Differences may be related to relative potencies of the compounds for monoamine reuptake inhibition.

Clomipramine, a better reference drug for panic/agoraphobia. II. Psychomotor and cognitive effects

The present reference drugs for the treatment of panic disorder and agoraphobia are imipramine and alprazolam. The latter decreases performance and cognitive functioning. No study of such functions in panic/agoraphobia is available. Fifty four out-patients meeting DSM-III-R criteria for panic disorder with or without agoraphobia (PAG), taking part in a parallel groups controlled trial of imipramine (mean dose ±SEM 114±9 mg), clomipramine (50±4 mg) and propanteline (active placebo) over 8 weeks, were studied. A test battery of psychomotor and memory tests was administered at baseline, and after 1, 4 and 8 weeks of treatment. Their results were compared (at baseline and at the end of the trial) with those of a control group of 57 normal untreated subjects. There was no difference between treatments, and no drug effect on any test at any time. No consistent difference between patients and controls was detected. Given its apparently higher potency, and the absence of deleterious effects on cognitive measures known to be affected by benzodiazepines, we conclude that clomipramine is better than imipramine or alprazolam as a reference drug for panic/agoraphobia.

Disappearance of memory deficits in outpatient depressives responding to imipramine

We evaluated learning and memory in 50 depressed patients prior to and following 4 week treatment with imipramine compared to 21 normal controls tested at corresponding times. At baseline, the depressives did worse than normals on most memory tasks with the difficult memory tasks, regardless of store, modality or type of task best distinguishing between depressive and normal memory. Following imipramine treatment, responders performed better than nonresponders on the difficult memory tasks, and not significantly differently from controls on most tasks. This, as well as the fact that the responders improved to a greater degree than controls on most measures (in a few cases the difference was statistically significant) and the fact that at 4 weeks complete responders to imipramine did significantly better than partial responders to imipramine, indicates that relief from depression is highly related to improved memory functioning. The finding that complete responders to imipramine were not significantly worse than normal controls suggests that imipramine did not have significant adverse effects on memory.

A comparison of the effect of fluoxetine and trazodone on the cognitive functioning of depressed outpatients

Tricyclic antidepressants with clinically significant amounts of anticholinergic activity can adversely affect memory and cognitive functioning. The study evaluated the effect of two non-anticholinergic antidepressants, fluoxetine and trazodone, on immediate and short-term memory in clinically depressed outpatients. The results of this study demonstrated that neither drug affected the depressed patients' cognitive skills as measured by the Guild memory test (digit span and paired associations) during their treatment and recovery. The only factor that was useful in predicting an improvement in cognitive functioning was the change in the measures of depression (Hamilton Rating Scale for Depression and Clinical Global Impression) with time.

Self-administration in baboons and the discriminative stimulus effects in rats of bupropion, nomifensine, diclofensine and imipramine

The behavioral effects of the antidepressants nomifensine, diclofensine, bupropion, and imipramine were examined using a cocaine substitution drug self-administration procedure in baboons and a cocaine drug discrimination procedure in rats. Intravenous self-administration of the antidepressants was examined in baboons under conditions in which baseline responding was maintained by intravenous injections of cocaine HCl (0.32 mg/kg/injection). Drug was available under a fixed-ratio 80-response or 160-response schedule of intravenous injection. Each drug injection was followed by a 3-h time-out allowing a maximum of eight injections per day. The antidepressants or their vehicles were substituted for cocaine for a period of 15 days, followed by a return to the cocaine baseline. Nomifensine, diclofensine and bupropion all maintained self-administration behavior at levels above those maintained by their respective vehicles. Some doses of nomifensine, diclofensine, and bupropion maintained levels of behavior similar to those maintained under baseline cocaine conditions. High doses of imipramine maintained levels of behavior above those maintained by its vehicle, but the amount of behavior maintained under these conditions was extremely small. In a second experiment rats were trained to discriminate 32 mumol/kg cocaine (IP 10 min presession) from no drug in a two-lever food reinforced drug discrimination procedure in which responding on one lever was reinforced following ten consecutive responses when the session was preceded by cocaine administration, while responding on the other lever was similarly reinforced in the absence of cocaine pretreatment. Cocaine, nomifensine, diclofensine, and bupropion all dose-dependently occasioned cocaine-appropriate responding. Imipramine did not occasion cocaine-appropriate responding over a range of behaviorally active doses.

Motor performance in hyperactive children treated with imipramine

The effects of the tricyclic antidepressant imipramine were evaluated in a study of 9 children with Attention Deficit-Hyperactivity Disorder. The study was double-blind, placebo-controlled, with three drug conditions, low, medium, and high doses. The focus was on neuropsychological drug effects. Imipramine exerted negative dose-response effects on motor performance (motor speed, motor pursuit), while it improved hyperactive behavior and attention and raised the heart rate slightly.

Brain output dysregulation induced by olfactory bulbectomy: an approximation in the rat of major depressive disorder in humans?

Mounting evidence indicates that the emotional, cognitive, neurovegetative and behavioral symptoms of patients with major depressive disorder are due to abnormal neurochemical substrates in the brain. Although the specific neurochemical abnormalities responsible have not been identified, the presenting symptoms of major depression are consistent with a disruption of normal neural communications between the limbic system and hypothalamus. Following removal of the olfactory bulbs, rats display a syndrome of behavioral deficits that also reflect a disruption of the limbic-hypothalamic axis. Moreover, the bulbectomy induced deficits are selectively reduced by the chronic administration of the same drugs that alleviate the symptoms of depression when given chronically to the patients. In addition to this pharmacological similarity, there are also numerous behavioral parallels between bulbectomized rats and major depression patients. The bulbectomized rat provides a good model in which to study antidepressant drugs and also may provide neurochemical and neuroanatomical data that are relevant to understanding the biological substrates of emotion and the causes of depression in humans.

Interaction of alcohol with maprotiline or nomifensine: echocardiographic and psychometric effects

Eight healthy volunteers received low doses of maprotiline and nomifensine up to 50 mg b.d. for 15 days in a double-blind, cross-over, placebo controlled study, during which echocardiography and psychomotor testing were carried out before and after the intake of alcohol 1 g/kg. Maprotiline increased heart rate and cardiac output and reduced peripheral resistance compared to placebo and nomifensine. Nomifensine alone was associated with a slight decrease in heart rate. Alcohol alone caused a significant increase in diastolic blood pressure, but did not otherwise modify the cardiovascular measures. The antidepressants did not augment the effects of alcohol. Antidepressants alone had no effect on psychomotor skills, but alcohol always impaired performance. No additional effects of alcohol were produced by the antidepressants. It appears that practically important peripheral or central consequences are unlikely to follow drinking a moderate amount of alcohol during regular therapy with low therapeutic doses of catecholamine reuptake inhibiting antidepressants. Experimental studies of the interaction of antidepressants and alcohol in patients with chronic heart disease seem to be justified.

Human cognitive function following binedaline (50 mg and 100 mg) and imipramine (75 mg): results with a new battery on tests

The effects of two single oral doses of binedaline (50 and 100 mg), imipramine (75 mg) and placebo were compared on a range of psychological tasks (logical reasoning, the Stroop test, and five-choice serial reaction) in healthy young volunteers. The tasks, together with a mood adjective check-list, were completed prior to drug administration and 1, 2, 4 and 8 h post-dose. Binedaline had no significant effect on any of the task parameters. Imipramine impaired performance on all but the Stroop test at 2 h after drug administration. At 1, 2 and 4 h, ratings on the "deactivation" dimension of the mood adjective check-list were significantly higher following imipramine when compared to placebo. The results are discussed in terms of some general considerations about the selection and scoring of tasks to be used in the screening of drugs.

Cognitive impairment in tardive dyskinesia

Psychiatric patients in a prospective study on tardive dyskinesia (TD) development were psychometrically evaluated before TD onset to see whether cognitive impairment predisposes an individual to greater risk for TD. It was found that patients with TD showed more preexisting cognitive impairment than did the non-TD controls.

Second generation antidepressants: a comparative review

The authors review four "second generation" antidepressants (maprotiline, amoxapine, trazodone, and nomifensine) in terms of action on biogenic amines and receptors, antidepressive efficacy, and adverse effects. Doxepin is used as a comparative agent and is similar to the prototypical tricyclic agents in all the above categories. Maprotiline is a selective noradrenergic agent, but shares a similar adverse effect profile with doxepin and may be associated with a high frequency of seizures in overdose. Amoxapine is a mixed action antidepressant with significant neuroleptic activity in vivo. Its adverse effect profile is highlighted by symptoms related to its neuroleptic activity, and seizures and acute renal failure in overdose. Trazodone is a selective serotonergic agent with low anticholinergic activity, and minimal morbidity/mortality in overdose. Reports of priapism, leading to impotence in some men, however, is of concern. Nomifensine is a potent noradrenergic and dopaminergic agent with low anticholinergic activity, and minimum cardiotoxicity and low morbidity/mortality in overdose. Its most important adverse effects include overstimulation and infrequent, usually reversible, immunologic hypersensitivity reactions. Trazodone and nomifensine have favorable profiles for use in the elderly. Trazodone may be more favorable in the anxious/agitated patient due to its sedative effects, whereas nomifensine may be more beneficial in the retarded, apathetic patient.

The effects of desmethylimipramine on cognitive function in healthy subjects

The cognitive effects of the specific norepinephrine (NE) uptake inhibitor desmethylimipramine (DMI) were examined in normal subjects. Although there were no differences in performance on drug compared to placebo treatment, there was an improvement in cognition 1 week after the drug had been discontinued. On DMI, there was evidence for increased noradrenergic activity, which was uncorrelated with measures of learning and memory. An improvement in mood during drug withdrawal was uncorrelated with the cognitive enhancement. It was concluded that the discontinuation of DMI, a drug which primarily affects NE uptake, improves several measures of learning and memory. Drug effects on cognition may be most pronounced during the withdrawal period.

Effects of zimeldine and other antidepressants on skilled performance: a comprehensive review

Existing data suggest that amitriptyline, doxepin, mianserin, viloxazine and imipramine impair the performance of skilled psychomotor tasks. The degree of impairment, as well as the degree of interaction with alcohol, is closely related to the sedative potency of the drug. the adverse effects on psychomotor skills are, however, mainly limited to the first 10 days of treatment. In contrast, nortriptyline, clomipramine, desipramine, protriptyline, nomifensine and zimeldine have much less marked effects on skilled performance. Despite its being a relatively new antidepressant, the effects of zimeldine on psychomotor skills have already been extensively investigated. It has been shown to be without stimulant or sedative effects, and there does not appear to be any additive effect between zimeldine and ethanol. The lack of detrimental effects on skills related to such tasks as driving, makes zimeldine suitable for use in out-patient populations.

Non-MAOI antidepressant drugs and cognitive functions: a review

Little is known about the effects of non-MAOI antidepressants on cognitive functions, despite their wide application to ambulant patients. Evidence from studies involving healthy volunteers suggests that differences exist between drugs, with imipramine, amitriptyline and mianserin being associated with the most marked detrimental effects. However, these findings have generally not been supported by the few studies using clinical populations, for which improvements in cognitive functions are often recorded following treatment. The reasons for this discrepancy are discussed, and the need for further research suggested.

Intravenous self-administration of nomifensine in rats: implications for abuse potential in humans

Rats acquired and maintained intravenous self-administration of nomifensine, a new antidepressant compound. Additional experiments implicated dopamine-containing neurons in this behavior. These findings, along with the marked pharmacological similarities between nomifensine and such drugs as cocaine and methylphenidate, indicate a potential for nomifensine abuse by humans.

Psychomotor changes during initial day of benzodiazepine medication

1 The detracting psychomotor effects of diazepam (5 mg three times daily) and clobazam (an investigational 1,5-benzodiazepine) were compared with placebo effects over the course of the initial day of medication. Tests were administered at hourly intervals and the data were analyzed from the standpoint of contrasts at each session and from the standpoint of trends that accrued during the course of the day. 2 It is concluded that among normal volunteers diazepam 5 mg three times daily may be near the threshold for detracting psychomotor consequences during the initial day and that clobazam seems to be without detracting consequences and may have some enhancing effects.

Effects of benzodiazepines on psychomotor performance

1 The literature relating to the effects of benzodiazepines on psychomotor performance is critically reviewed. 2 The multiple and diverse psychomotor tests used are assessed according to their ability to demonstrate differences between drugs. 3 Three general conclusions are: (1) The speed with which simple acts of a repetitive nature are performed may be impaired by benzodiazepines. (2) learning and immediate memory will also be impaired. (3) there is relatively little indication that well established higher mental faculties are adversely involved.

Cardiological effects of nomifensine, a new antidepressant

A cardiovascular study of a new antidepressant, nomifensine, revealed no significant cardiac effects in eight ambulant patients who received up to 200 mg of nomifensine per day for three weeks. In an electro-physiological study of cardiac conduction, nomifensine had significantly less effect on cardiac activity than amitriptyline and doxepin. Results of the clinical and the experimental studies suggest that nomifensine may be of value in treating the depressed patient with heart disease.

Dynamic interaction of nomifensine with alcohol

1. Nine healthy volunteers participated in a comparative study of the effects of nomifensine, nomifensine plus alcohol, and placebo plus alcohol, on aspects of psychomotor performance. 2. The study was carried out according to a Latin square design and each treatment was separated from the preceding treatment by 7 days. 3. Placebo plus alcohol impaired performance, increased pulse rate and blood pressure, and increased feelings of activity and euphoria. 4. Nomifensine plus alcohol produced the same subjective and objective changes as placebo plus alcohol, but in no instance were changes any greater. 5. Nomifensine alone produced none of these changes. 6. It was concluded that single doses of nomifensine did not potentiate the effect of alcohol.

Contrasts in antidepressant medications

1 Two studies are reviewed, one in depressed patients, the other in healthy volunteers.

2 The effect of nomifensine and imipramine on depressed out-patients has been studied in a controlled double-blind manner. Treatment lasted for 4 weeks and assessments were carried out before and at weekly intervals during the study. These involved use of a self-rating scale and four observer rating scales.

3 In the self-rating scale, 13 of the 14 discriminating items favoured nomifensine, and indicated that it possessed a strengthening or energizing activity, and analysis of individual items on the Hamilton Depression Scale confirmed this.

4 In this study, imipramine showed greater effect on mood and on sleep disturbances.

5 A comparison of nomifensine, imipramine and placebo was carried out in 90 volunteers in a double-blind randomized study. Each volunteer received three doses of medication during the study day.

6 The assessments include a Digit Symbol Substitution Test, the production of a temporal interval, and a simple and a complex test of attention or vigilance.

7 The influence of nomifensine on these tests could not be distinguished from that of placebo. There was evidence, however, that imipramine depressed performance and possessed a sedative effect.

8 The results of both studies, when considered together, are essentially in agreement.

A profile of nomifensine

1. Nomifensine is a new antidepressant of novel chemical structure (a tetrahydroisoquinoline) with a pharmacological and therapeutic profile which differentiates it from any existing group of psychotropic agents. 2. The basic animal pharmacological profile is similar to that of the tricyclic antidepressants, imipramine and desmethylimipramine, but with a comparative lack of peripheral anticholinergic and cardiotoxic effects. 3. The pattern of effects on monoamine neurotransmitters is unique amongst antidepressants in that nomifensine is a potent dopamine agonist, has a powerful inhibitory effect on noradrenaline uptake and a weaker inhibitory effect on serotonin uptake. These pharmacological differences are reflected in the behavioural activity of the drug. 4. Clinically nomifensine has been shown to be an effective non-sedative antidepressant; its relative lack of anticholinergic and other somatic side-effects (particularly on the cardiovascular system) have been confirmed in patients.