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PubMed1981

Action of dextroamphetamine on dopamine sensitive cells in the snail brain.

Presynaptic and postsynaptic actions of dextroamphetamine (DEX) were studied on dopamine (DA) sensitive neurons of the subesophageal ganglion of the garden snail Helix aspersa utilizing standard microelectrode techniques. Dextroamphetamine (5.5 X 10(-7)-10(-4)M) produced effects on DA-sensitive neurons similar to that caused by DA (5.5 X 10(-7)-10(-4)M). On cells excited by DA, surfused DEX (5.5 X 10(-7)M) caused an excitation that could be blocked by chlorpromazine (0.5-1 X 10(-6)M) or haloperidol (0.5-1 X 10(-6)M). Elevating the extracellular Mg2+ from 4 to 20 mM reduced the depolarization caused by DEX from 11 to 2.5 mV without affecting the response to DA. The response remaining is attributed to a direct response to DEX on DA receptors. Surfused DEX caused an inhibition of cells inhibited by DA. Both DA and DEX effects were selectively blocked by dihydroergotamine (0.5-1 X 10(-6)M). Elevating the [Mg2+] decreased the hyperpolarization caused by DEX from 11 to 3 mV without affecting the DA response. The effect of elevated magnesium in decreasing responses to surfused DEX suggests that the primary action of DEX is at the nerve terminal to cause DA release. Iontophoretic application of DEX caused minimal excitation or inhibition of DA neurons. This is attributed to the fact that DA receptors at the site of drug application are not associated with synaptic innervation. The response obtained with iontophoretically applied DEX suggest a weak direct action on DA receptors.

Animals↗
PubMed1981

Autonomic effects of dextroamphetamine in normal men: implications for hyperactivity and schizophrenia.

This study test the effects on autonomic nervous system (ANS) activity of two doses (0.25 mg/kg and 0.50 mg/kg) of dextroamphetamine in normal men. Skin conductance and heart rate were recorded during rest, tone presentation, and a reaction time task. Compared to placebo, dextroamphetamine increased both skin conductance and heart rate indices of arousal, slowed habituation, and reduced ANS responsivity selectively to more important vs. less important stimuli. The last result differs from previous findings on hyperactive and normal boys. The pattern of ANS effects closely resembles findings on drug-free schizophrenics, suggesting that it may be a matter for biologic changes occurring in amphetamine psychosis and spontaneous psychotic episodes.

Adult↗
PubMed1984

Cortisol response to dextroamphetamine stimulation in depressed outpatients.

Endogenously depressed inpatients often fail to release cortisol following intravenous (i.v.) amphetamine, unlike nondepressed control subjects. We therefore assessed the ability of i.v. dextroamphetamine, 0.15 mg/kg, to induce cortisol release in 64 depressed outpatients diagnosed according to Research Diagnostic Criteria (RDC). After dextroamphetamine challenge, more patients with major depression failed to release substantial cortisol (30%) than those without major depression (5%). Major depressives with endogenous subtype failed to release cortisol (38%) more frequently than those without endogenous depression (23%), but this difference was not significant. After baseline cortisol, sex, and weight loss were controlled for in a regression analysis, however, RDC diagnosis of major depression or endogenous subtype did not account for significant additional variance in cortisol release. In outpatients, abnormal cortisol response to amphetamine may be more closely related to baseline cortisol, sex, and history of weight loss than to RDC subtype of depression.

Adult↗
PubMed1994

Effect of dextroamphetamine and methylphenidate on calcium and magnesium concentration in hyperactive boys.

Levels of calcium in plasma, red blood cells, and mononuclear blood cells, levels of calcium in plasma, and the plasma calcium-to-magnesium ratio were measured at baseline and after 3 weeks of each drug phase of a double-blind, placebo-controlled study of methylphenidate and dextroamphetamine in hyperactive boys. Levels of magnesium in plasma were significantly higher after 3 weeks of dextroamphetamine treatment, and the calcium-to-magnesium ratio was significantly lower after 3 weeks of either drug compared with the baseline or placebo condition. There was no change in magnesium levels in red blood cells or mononuclear blood cells. These measures were obtained 30 minutes before the morning dose and at 9 a.m., 9:30 a.m., 10:30 a.m., 11:00 a.m., and noon on the last day of each 3-week phase. Analysis of variance revealed a drug effect on plasma magnesium and on the calcium-to-magnesium ratio but no drug x time interaction. Although these changes were not correlated with the time course of acute symptomatic response to stimulant therapy, the decrease in the ratio may be relevant to side effects and treatment resistance associated with stimulant use.

Attention Deficit Disorder with Hyperactivity↗
PubMed1986

Dextroamphetamine-induced arousal in human subjects as a model for mania.

Because of the practical difficulties which arise in studying manic patients, a reproducible model for mania using human subjects would be a valuable adjunct to research in this condition. Dextroamphetamine, given as a single oral 20 mg dose, fulfils the criteria for such a model in that there are very close similarities between the changes which occur after dextroamphetamine and those which have been observed in mania in terms of subjective experience, physiological and endocrine changes, and response to pharmacological agents.

Administration, Oral↗
PubMed2006

The effects of caffeine, dextroamphetamine, and modafinil on humor appreciation during sleep deprivation.

STUDY OBJECTIVES: Sleep loss consistently impairs performance on measures of alertness, vigilance, and response speed, but its effects on higher-order executive functions are not well delineated. Similarly, whereas deficits in arousal and vigilance can be temporarily countered by the use of several different stimulant medications, it is not clear how these compounds affect complex cognitive processes in sleep-deprived individuals. DESIGN: We evaluated the effects of double-blind administration of 3 stimulant medications or placebo on the ability to appreciate humor in visual (cartoons) or verbal (headlines) stimuli presented on a computer screen following 49.5 hours of sleep deprivation. SETTING: In-residence sleep-laboratory facility at the Walter Reed Army Institute of Research. PARTICIPANTS: Fifty-four healthy adults (29 men, 24 women), ranging in age from 18 to 36 years. INTERVENTIONS: Each participant was randomly assigned to 1 of 3 stimulant medication groups, including caffeine, 600 mg, n = 12; modafinil, 400 mg, n = 11; dextroamphetamine, 20 mg, n = 16; or placebo, n = 14. MEASUREMENTS AND RESULTS: Humor appreciation for cartoon stimuli was enhanced by modafinil relative to both placebo and caffeine, but there was no effect of any stimulant medication on the appreciation of verbal humor during sleep loss. In contrast, all 3 stimulants improved psychomotor response speed, whereas only caffeine and dextroamphetamine improved ratings of subjective sleepiness. CONCLUSIONS: Findings suggest that, despite similar alerting and vigilance-promoting effects, these 3 compounds have significantly different effects on those highly complex cognitive abilities mediated by the pre-frontal cortex.

Adolescent↗
PubMed1986

Noradrenergic mechanisms in the response to dextroamphetamine in humans.

The effect of oral thymoxamine, an alpha-noradrenergic antagonist, on the arousal and anorectic action of oral dextroamphetamine was measured in order to investigate the role of the alpha-noradrenergic pathways in these responses. Thymoxamine appeared to accentuate the alerting action and reduce the anorectic action of dextroamphetamine. The implications of these findings on the role of the alpha-noradrenergic pathways in these responses is discussed in the light of previous findings.

Adult↗
PubMed1967

Effects of magnesium pemoline and dextroamphetamine on human learning.

Two central nervous system stimulants, magnesium pemoline and dextroamphetamine, were tested to see if they facilitate learning in human subjects. Subjects under placebo learned faster than the subjects under any of the several doses of magnesium pemoline; however, none of these differences reached statistical significance. Subjects who received dextroamphetamine learned significantly more slowly than those who received placebo.

Adult↗
PubMed1991

Cognitive and behavioral effects of the coadministration of dextroamphetamine and haloperidol in schizophrenia.

OBJECTIVE: The authors sought to determine if an acute dose of dextroamphetamine might have positive effects on affect and cognition in schizophrenic patients maintained on a regimen of haloperidol and, if so, what variables might predict such improvements. METHOD: Twenty-one patients with chronic schizophrenia who were hospitalized on a research ward received a single oral dose of dextroamphetamine (0.25 mg/kg) in a double-blind, placebo-controlled, crossover study. All patients were receiving 0.4 mg/kg per day of haloperidol. Cognitive tests, motor tests, global ratings, mood ratings, and videotape ratings were used to determine the effect of the coadministration of these drugs. Ventricle-brain ratios derived from CT scans were used to predict response to the coadministration of these drugs. RESULTS: Amphetamine improved performance on a measure of concept formation on the Wisconsin Card Sorting Test but did not result in changes in performance on tests of memory or attention. As a group, the patients were more active and performed psychomotor tests more quickly while receiving amphetamine. Six patients were judged by clinical raters to have improved in terms of affect, cooperation, and engagement with the environment. Improvement was associated with enlarged cerebral ventricles and increases in blink rate from the placebo to the active drug condition. No patient unequivocally worsened. CONCLUSIONS: These results may be consistent with the theory that coadministration of amphetamine and haloperidol produces relatively selective enhancement of cortical dopaminergic activity. However, because of the acute nature of the trial and the specialized research environment in which it was conducted, the authors do not advocate amphetamine as a routine clinical treatment of schizophrenia.

Adult↗
PubMed1964

[COMPARATIVE EVALUATION OF THE SUBJECTIVE EFFECTS OF DEXTROAMPHETAMINE, METHYLPHENIDATE AND PLACEBO].

The subjective effects of dextroamphetamine, methylphenidate and placebo were evaluated in 16 medical students during the period just prior to their final oral examinations. The subjects served as their own controls. The order of administration of the three medications for each student was randomized, and a double-blind technique was used throughout. A questionnaire method was employed for the collection of results, which proved to be a useful and effective means. It demonstrated that dextroamphetamine, methylphenidate and placebo were statistically different from one another with regard to their effect on efficiency of studying, fatigue, duration of sleep and appetite. There were also significant differences in the number of side effects caused by the three medications. The stimulants, however, did not increase the number of study hours, nor was their use recommended by the students when preparing for important examinations.

Appetite↗
PubMed1991

A comparative study of the driving effects of dextroamphetamine and yogic meditation on muscle control for the performance of balance on balance board.

The work is aimed to compare the relative strength of dextroamphetamine and yogic meditation on the performance of 3 different groups of medical students to concentrate on the task to balance on a balance board. Group A subjects were mediators, group B subjects were given orally 5 and 10 mg of dextroamphetamine in a capsule, 1 hr prior to the test. Group C subjects were given same capsule but with lactose in place of the drug (placebo). This last groups served as control for the study. The balance index calculated taking into account their balance time and error score at each trial of 5 min duration showed that the performance of the group B (drug) had declined with overall percentile fall of 40.6% as compared to the performance of the controls (placebo) whereas, the performance of Group A (meditators) went on steadily and progressively increasing throughout the period of 10 trial days with overall percentile rise of 27.8%. The results were conclusive to confirm earlier reports that amphetamine is not of use for improvement of task rather, it deteriorates the task performance. Contrary to that, yogic meditation is of merit to achieve concentration for mental as well as physical task.

Adolescent↗
PubMedDate not supplied

Mutagenicity obtained experimentally by oral administration of dextroamphetamine sulphate to the rat.

Research work on the possible mutagenic effects of the amphetamine, sympathomimetic amine, was carried out on the rat. The method used was the dominant lethal assay, in its sub-acute form. Dextroamphetamine sulphate was administered orally. At the dosage and frequency of the test, dextroamphetamine sulphate was found to be a significantly mutogenic agent. The over-all mutagenic index was 13.92% (P less than 0.01) for the test group and 8.90% for the control group.

Abnormalities, Drug-Induced↗
PubMed1977

Subjective responses and excretion patterns of dextroamphetamine after the administration of therapeutic doses.

Twelve male medical and graduate students received dextroamphetamine sulfate in doses of 0, 5, 10, and 15 mg/70 kg body weight. The study was conducted in a double-blind manner, and treatments were assigned according to randomized, complete block design. The drug was given orally and subjects were instructed not to eat 3 1/2 h prior to administration. After administration, total urine output was collected for 12 h; no attempt was made to control urinary pH to more realistically approach the general clinical usage of amphetamines. The urine was pooled into two 6-h segments and analyzed for amphetamine concentration. Subjective impressions of the treatments were also evaluated by means of the Cornell Medical Index Questionnaire. Results showed that approximately 30% of the total dose was excreted unchanged within 12 h after administration. The amount excreted agreed very closely with the doses given and paralleled the scores for subjective impressions by the subjects. None of the subjects felt that their driving would be impaired for any of the doses administered. This study indicates that under ordinary conditions (in which pH is not artificially controlled), therapeutic doses of dextroamphetamine can be detected in urine for up to 12 h after oral administration.

Administration, Oral↗
PubMed1987

Dextroamphetamine treatment of mania.

Five of six acutely manic patients treated with dextroamphetamine experienced a 50% or greater reduction in their mania severity scores. Side effects were noted in only one patient. The treatment results suggest that dextroamphetamine might be useful in the treatment of mania.

Acute Disease↗
PubMed1988

Effects of scopolamine and dextroamphetamine on human performance.

The effects of two drugs used to prevent symptoms of motion sickness in the operational environment were examined in this study of human performance as measured by computer-based tests of cognitive and psychomotor skills. Each subject was exposed repetitively to five tests: Symbol-Digit Substitution, Simple Reaction Time, Pattern Recognition, Digit Span Memory, and Pattern Memory. Although there have been previous reports of decreases in human performance in similar testing with higher dosages of scopolamine or dextroamphetamine, no significant decrements were observed with the operational-level combined dose used in this study (0.4 mg oral scopolamine and 5.0 mg oral dextroamphetamine.) The controversy over the use of combination drug therapy in this environment is discussed along with the indications for further research based on the findings.

Attention↗
PubMed1995

Case study: antimanic effectiveness of dextroamphetamine in a brain-injured adolescent.

A relatively enduring and counterintuitive antimanic response to dextroamphetamine in a brain-injured adolescent who had failed trials involving divalproex, lithium, haloperidol, and carbamazepine is described. This finding combined with data from previous reports of antimanic effects of test doses of stimulants imply that such a pharmacological probe may prove relevant for the prediction of treatment response of mania to dextroamphetamine and perhaps for subclassification of bipolar disorder.

Adolescent↗
PubMedDate not supplied

Medical prescription of dextroamphetamine during pregnancy.

Amphetamine and methamphetamine abuse complicate a significant number of pregnancies. This case report details medical prescription of dextroamphetamine during a complicated pregnancy. A review of the literature is included regarding fetal risks of dextroamphetamine and methamphetamine exposure.

Adult↗
PubMed1976

Growth of hyperkinetic children taking methylphenidate, dextroamphetamine, or imipramine/desipramine.

One hundred children with the hyperkinetic syndrome or minimal brain dysfunction syndrome were treated with medication: 60 with methylphenidate (Ritalin), 24 with dextroamphetamine (Dexedrine), and 16 with either imipramine or desipramine. The duration of treatment was for a minimum of two years, and averaged five years, with an average follow-up of six years from the onset of treatment. Their weight and height had been measured prior to treatment, and these and subsequent measurements were converted to percentiles, using the tables of norms of the Iowa City study. Initially there was a diminution in expected weight, but not height, but after a few years the growth in weight and height was found to be greater than predicted from the norms to a statistically significant degree. Gains in weight and height were greater for those whose medication had been stopped prior to the final measurements than for those still taking medication; but these differences did not reach statistical significance. No correlations were found between dosage level and changes in weight and height percentiles. It is concluded that there is no stunting of growth from the long-term use of methylphenidate, dextroamphetamine, or imipramine/desipramine in children. Any slowing of growth when treatment is first started is compensated for later on, both while the patient is still taking the medication, and after discontinuing it.

Adolescent↗