Amphetamine increases motivation of humans and mice as measured by breakpoint, but does not affect an Electroencephalographic biomarker

Translation of drug targets from preclinical studies to clinical trials has been aided by cross-species behavioral tasks, but evidence for brain-based engagement during task performance is still required. Cross-species progressive ratio breakpoint tasks (PRBTs) measure motivation-related behavior and are pharmacologically and clinically sensitive. We recently advanced elevated parietal alpha power as a cross-species electroencephalographic (EEG) biomarker of PRBT engagement. Given that amphetamine increases breakpoint in mice, we tested its effects on breakpoint and parietal alpha power in both humans and mice. Twenty-three healthy participants performed the PRBT with EEG after amphetamine or placebo in a double-blind design. C57BL/6J mice were trained on PRBT with EEG (n = 24) and were treated with amphetamine or vehicle. A second cohort of mice was trained on PRBT without EEG (n = 40) and was treated with amphetamine or vehicle. In humans, amphetamine increased breakpoint. In mice, during concomitant EEG, 1 mg/kg of amphetamine significantly decreased breakpoint. In cohort 2, however, 0.3 mg/kg of amphetamine increased breakpoint consistent with human findings. Increased alpha power was observed in both species as they reached breakpoint, replicating previous findings. Amphetamine did not affect alpha power in either species. Amphetamine increased effort in humans and mice. Consistent with previous reports, elevated parietal alpha power was observed in humans and mice as they performed the PRBT. Amphetamine did not affect this EEG biomarker of effort. Hence, these findings support the pharmacological predictive validity of the PRBT to measure effort in humans and mice and suggest that this EEG biomarker is not directly reflective of amphetamine-induced changes in effort.

Pharmacotherapy in autism spectrum disorders, including promising older drugs warranting trials

Available pharmacotherapies for autism spectrum disorders (ASD) are reviewed based on clinical and research experience, highlighting some older drugs with emerging evidence. Several medications show efficacy in ASD, though controlled studies in ASD are largely lacking. Only risperidone and aripiprazole have Federal Drug Administration approval in the United States. Methylphenidate (MPH) studies showed lower efficacy and tolerability for attention deficit hyperactivity disorder (ADHD) than in the typically developing (TD) population; atomoxetine demonstrated lower efficacy but comparable tolerability to TD outcomes. Guanfacine improved hyperactivity in ASD comparably to TD. Dex-troamphetamine promises greater efficacy than MPH in ASD. ADHD medications reduce impulsive aggression in youth, and may also be key for this in adults. Controlled trials of the selective serotonin reuptake inhibitors citalopram and fluoxetine demonstrated poor tolerability and lack of efficacy for repetitive behaviors. Trials of antiseizure medications in ASD remain inconclusive, however clinical trials may be warranted in severely disabled individuals showing bizarre behaviors. No identified drugs treat ASD core symptoms; oxytocin lacked efficacy. Amitriptyline and loxapine however, show promise. Loxapine at 5-10 mg daily resembled an atypical antipsychotic in positron emission tomography studies, but may be weight-sparing. Amitriptyline at approximately 1 mg/ kg/day used cautiously, shows efficacy for sleep, anxiety, impulsivity and ADHD, repetitive behaviors, and enuresis. Both drugs have promising neurotrophic properties.

Acute drug effects differentially predict desire to take dextroamphetamine again for work and recreation

RATIONALE

Misuse of dextroamphetamine occurs in work and recreational contexts. While acute drug effects broadly predict abuse liability, few studies have considered the relationship between acute effects and context.

OBJECTIVES

This study examined how individual differences in acute effects of dextroamphetamine relate to desire to take dextroamphetamine again in different contexts.

METHODS

This secondary analysis used data from healthy adults with no history of moderate-to-severe substance use disorder, who received oral doses of placebo and dextroamphetamine (10 and 20 mg) over 3 sessions under double-blind, randomized conditions. Subjects rated subjective effects and completed reward-related behavioral tasks. Subjects rated their desire to take dextroamphetamine again in hypothetical work and recreational contexts. Multilevel models examined within-subjects change scores (10 mg-placebo; 20 mg-placebo) to determine how subjective effects and behavioral outcomes predicted desire to take dextroamphetamine again for work versus recreation.

RESULTS

Subjects reported more desire to take 20 mg dextroamphetamine again for work than for recreation. At 20 mg, there was an interaction between context and liking/wanting, such that liking/wanting predicted desire to use dextroamphetamine for work only. There was also an interaction at 20 mg between context and psychomotor speed, such that psychomotor speed predicted interest in using dextroamphetamine for recreation only.

CONCLUSIONS

We found that positive subjective effects predicted desire to use dextroamphetamine again for work, while increased motor effects predicted desire to use dextroamphetamine recreationally. Hedonic effects may be perceived as advantageous when working, while increased physical energy may be preferred during recreation, suggesting that context of intended use is important when examining abuse liability.

Exploring the effectiveness of dextroamphetamine for the treatment of stimulant use disorder: a qualitative study with patients receiving injectable opioid agonist treatment

Background

A high proportion of people receiving both oral and injectable opioid agonist treatment report concurrent use of stimulants (i.e. cocaine and or amphetamines), which has been associated with higher rates of continued illicit opioid use and treatment dropout. A recent randomized controlled trial demonstrated the effectiveness of dextroamphetamine (a prescribed stimulant) at reducing craving for and use of cocaine among patients receiving injectable opioid agonist treatment. Following this evidence, dextroamphetamine has been prescribed to patients with stimulant use disorder at a clinic in Vancouver. This study investigates perceptions of the effectiveness of dextroamphetamine from the perspective of these patients.

Methods

Data were collected using small focus groups and one-on-one interviews with patients who were currently or formerly receiving dextroamphetamine (n = 20). Thematic analysis was conducted using an iterative approach, moving between data collection and analysis to search for patterns in the data across transcripts. This process led to the defining and naming of three central themes responding to the research question.

Results

Participants reported a range of stimulant use types, including cocaine (n = 8), methamphetamine (n = 8), or both (n = 4). Three central themes were identified as relating to participants’ perceptions of the effectiveness of the medication: 1) achieving a substitution effect (i.e. extent to which dextroamphetamine provided a substitution for the effect they received from use of illicit stimulants); 2) Reaching a preferred dose (i.e. speed of titration and effect of the dose received); and 3) Ease of medication access (i.e. preference for take home doses (i.e. carries) vs. medication integrated into care at the clinic).

Conclusion

In the context of continued investigation of pharmacological treatments for stimulant use disorder, the present study has highlighted how the study of clinical outcomes could be extended to account for factors that contribute to perceptions of effectiveness from the perspective of patients. In practice, elements of treatment delivery (e.g. dosing and dispensation protocols) can be adjusted to allow for various scenarios (e.g. on site vs. take home dosing) by which dextroamphetamine and other pharmacological stimulants could be implemented to provide “effective” treatment for people with a wide range of treatment goals and needs.

Exposure to methylphenidate during peri-adolescence decouples the prefrontal cortex: a multimodal MRI study

This study was designed to assess the effects of daily psychostimulant exposure during juvenility and peri-adolescence on brain morphology and functional connectivity using multimodal magnetic resonance imaging. We hypothesized that long-term exposure to methylphenidate would enhance connectivity with the prefrontal cortex. Male rats were given daily injections of either methylphenidate (n=10), dextroamphetamine (n=10) or saline vehicle (n=10) from postnatal day 21 to 42. They were imaged between postnatal day 43 and 48. Voxel-based morphometry, diffusion weighted imaging, and resting state functional connectivity were used to quantify brain structure and function. Images from each modality were registered and analyzed, using a 3D MRI rat atlas providing site-specific data over 171 different brain areas. Following imaging, rats were tested for cognitive function using novel object preference. Long-lasting psychostimulant treatment was associated with only a few significant changes in brain volume and measures of anisotropy compared to vehicle. Resting state functional connectivity imaging revealed decreased coupling between the prefrontal cortex, basal ganglia and sensory motor cortices. There were no significant differences between experimental groups for cognitive behavior. In this exploratory study, we showed that chronic psychostimulant treatment throughout juvenility and preadolescence has a minimal effect on brain volume and gray matter microarchitecture, but significantly uncouples the connectivity in the cerebral/basal ganglia circuitry.

Use of sustained release dextroamphetamine for the treatment of stimulant use disorder in the setting of injectable opioid agonist treatment in Canada: a case report

BACKGROUND

For people with opioid use disorder who are not responding to oral opioid agonist treatment, evidence supports the effectiveness of injectable opioid agonist treatment with injectable hydromorphone (an opioid analgesic) and diacetylmorphine (pharmaceutical grade heroin). While this treatment is effective at reducing illicit opioid use, concurrent cocaine use is prevalent. Dextroamphetamine (a central nervous system stimulant) has been found to be a safe and effective treatment for cocaine dependence among people receiving injectable opioid agonist treatment in Europe. We present the first report of dextroamphetamine prescribing offered for the treatment of stimulant use disorder among a patient receiving iOAT outside of a clinical trial. This case report can be used to inform clinical practice in the treatment of cocaine use disorder, an area where interventions are currently lacking.

CASE PRESENTATION

Dextroamphetamine was prescribed to a 51-year-old male who was diagnosed with concurrent opioid and stimulant use disorder in an injectable opioid agonist treatment clinic in Vancouver, Canada. He reported smoking crack cocaine daily for more than two decades and was experiencing health consequences associated with this use. He presented to his routine physician visit with the goal of reducing his cocaine use and was prescribed dextroamphetamine for the treatment of stimulant use disorder. After 4-weeks the patient was tolerating the medication with no observed adverse events and was achieving his therapeutic goal of reducing his cocaine use.

CONCLUSIONS

Dextroamphetamine can be prescribed to support patients with stimulant use disorder to reduce or stop their use of cocaine. The case demonstrated that when dextroamphetamine was prescribed, a significant reduction in cocaine use was experienced among a patient that had been regularly using cocaine on a daily basis for many years. Daily contact with care for the opioid medication promoted adherence to the stimulant medication and allowed for monitoring of dose and tolerance. Settings where patients are in regular contact with care such as oral and injectable opioid agonist treatment clinics serve as a suitable location to integrate dextroamphetamine prescribing for patients that use illicit stimulants to reduce use and associated harms.

Treatment of Hypothalamic Obesity with Dextroamphetamine: A Case Series

BACKGROUND

A limited number of published case reports suggest a positive effect of dextroamphetamine, an adrenergic agonist affecting both the central nervous system (CNS) and peripheral nervous system, on physical activity and weight in patients with hypothalamic obesity (intractable obesity following CNS insult). Here, we present our clinical experience with dextroamphetamine treatment for hypothalamic obesity.

METHODS

The clinical course of all patients started on dextroamphetamine treatment for severe hypothalamic obesity at our institution between 2010 and 2013 is reported. Dextroamphetamine administration was initiated at a single dose of 5 mg per day and titrated to effect up to a dose of 20 mg/day. BMI z-score velocity was calculated as change in BMI z-score over standardized intervals of 12 months. Parameters of treatment success and adverse events were assessed in a standardized fashion.

RESULTS

Seven patients (2 males; mean age 17.6 years [range 12.9-24.5]) underwent individual treatment attempts with dextroamphetamine between 2010 and 2013. The primary diagnoses were craniopharyngioma (n = 4), ganglioglioma WHO I (n = 1), astrocytoma (n = 1), and neonatal meningitis (n = 1). Time from initial CNS insult to initiation of dextroamphetamine treatment averaged 5.2 years (range 2.4 months to 16.5 years). All patients demonstrated a steady increase in BMI z-score from the time of initial diagnosis until initiation of dextroamphetamine treatment. Mean baseline BMI z-score was +3.17 ± 0.93 (+1.9 to +4.4). Mean BMI z-score velocity decelerated to -0.18 ± 0.12 per year during the first year of treatment and stabilized at +0.05 ± 0.32 per year during the second year of treatment. No significant adverse events were reported.

CONCLUSION

Dextroamphetamine treatment led to stabilization or reduction of BMI z-score in a cohort of 7 patients with hypothalamic obesity, with no adverse effects. Considering the projected increase in BMI z-score according to the natural course of the disease, these findings are promising and warrant further study.

Low-Dose d-Amphetamine Induced Regression of Liver Fat Deposits in Dercum Disease

BACKGROUND

Dercum disease is a rare disorder of painful subcutaneous adipose tissue masses typically presenting as a constellation of signs and symptoms affecting most organs, including slow lymphatic flow and fatty liver.

METHOD

The University of Arizona Institutional Review Board considered this report exempt after patient consent. Multislice, multisequence magnetic resonance imaging (MRI) of the abdomen and pelvis was performed prior to and after d-amphetamine, with and without intravenous gadolinium.

RESULTS

Initial MRI demonstrated hepatic steatosis in Case 1; Case 2 had 2-subcentimeter lipid foci within the liver. Initiation of 10-20 mg d-amphetamine decreased liver lipid deposition from 16% to 4% in Case 1 and resolved fat deposits in Case 2 after ~1 year.

CONCLUSION

There is a dire need for novel treatment options for nonalcoholic fatty liver disease to prevent progression to cirrhosis. Reduction of liver fat by d-amphetamine suggests a potential therapeutic role in nonalcoholic fatty liver disease.

Effects of methylphenidate during emotional processing in amphetamine users: preliminary findings

D-amphetamine (dAMPH) and methylphenidate (MPH) are stimulants used in the treatment of Attention Deficit Hyperactivity Disorder (ADHD). Preclinical studies have shown that in healthy animals, dAMPH induces dopamine (DA) dysfunction, as evidenced for instance by loss of DA levels and its transporters. It has also been suggested that DA plays an important role in emotional processing, and that altered DA-ergic intervention may modulate amygdala function. To explore the role of the DA system in emotional processing we examined emotional processing using functional magnetic resonance imaging (fMRI) in eight male recreational users of dAMPH and eight male healthy controls. We compared brain activation between both groups during an emotional face-processing task with and without an oral MPH challenge. All subjects were abstinent for at least 2 weeks during the baseline scan. The second scan was performed on the same day 1½ hours after receiving an oral dose of 35 mg MPH. A significant Valence*Group interaction (p = .037) indicated amygdala hyperreactivity to fearful facial expressions in dAMPH users that was robust against adjustment for age (p = .015). Furthermore, duration of amphetamine use in years was positively correlated with amygdala reactivity in dAMPH users (r = .76; p = .029). These exploratory findings are in line with previous findings suggesting that DA plays a role in emotional processing.

An Infant with a Prolonged Sympathomimetic Toxidrome after Lisdexamfetamine Dimesylate Ingestion

INTRODUCTION

Stimulant medications are approved to treat attention deficit hyperactivity disorder (ADHD) in children over the age of 6 years. Fatal ingestion of stimulants by children has been reported, although most ingestions do not result in severe toxicity. Lisdexamfetamine dimesylate, a once daily long-acting stimulant, is a prodrug requiring conversion to its active form, dextroamphetamine, in the bloodstream. Based on its unique pharmacokinetics, peak levels of d-amphetamine are delayed. We describe a case of accidental ingestion of lisdexamfetamine dimesylate in an infant.

CASE REPORT

A previously healthy 10-month-old infant was admitted to the hospital with a 5-h history of tachycardia, hypertension, dyskinesia, and altered mental status of unknown etiology. Confirmatory urine testing, from a specimen collected approximately 16 h after the onset of symptoms, revealed an urine amphetamine concentration of 22,312 ng/mL (positive cutoff 200 ng/mL). The serum amphetamine concentration, from a specimen collected approximately 37 h after the onset of symptoms, was 68 ng/mL (positive cutoff 20 ng/mL). Urine and serum were both negative for methamphetamine, methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA, Ecstasy), and methylenedioxyethamphetamine (MDEA). During the hospitalization, it was discovered that the infant had access to lisdexamfetamine dimesylate prior to the onset of symptoms.

CONCLUSION

Amphetamine ingestions in young children are uncommon but do occur. Clinicians should be aware of signs and symptoms of amphetamine toxicity and consider ingestion when a pediatric patient presents with symptoms of a sympathetic toxidrome even when ingestion is denied.

Pilot study of the effects of lisdexamfetamine on cocaine use: A randomized, double-blind, placebo-controlled trial

BACKGROUND

Amphetamine analogs have been demonstrated to have some efficacy in reducing use in cocaine dependent individuals. However, these agents also have potential for abuse. Lisdexamfetamine (LDX), a lysine+dextroamphetamine formulation, has been approved for the treatment of Attention-Deficit/Hyperactivity Disorder (ADHD) and as a prodrug, has less abuse potential.

OBJECTIVE

This pilot study sought to evaluate the safety, tolerability, and efficacy of LDX as a candidate treatment for cocaine dependence.

METHODS

A randomized, double-blind, placebo-controlled parallel group study served to evaluate LDX in 43 cocaine-dependent individuals: (1) placebo (PBO; 0mg, n=21), (2) LDX (70mg, n=22). Participants received medication for 14 weeks. Cocaine use was determined based on urine analysis for benzoylecgonine (BE; a cocaine metabolite).

RESULTS

Retention rates were higher though not significantly different in the PBO (71.4%) than the LDX condition (57.1%). Compared to those in the PBO condition, those receiving LDX were more likely to report experiencing (ps<0.05) diarrhea (45.5% vs. 14.3%), headaches (45.5% vs. 9.5%), and anxiety (31.8% vs. 4.8%). No differences in medication conditions were observed for blood pressure, heart rate, or body weight. In the randomized sample, no differences in cocaine use were seen. Those receiving LDX reported significantly less craving for cocaine than participants receiving PBO.

CONCLUSIONS

LDX did not significantly reduce cocaine use compared to PBO in the randomized sample.

How treatable is refractory depression?

INTRODUCTION

Patients who do not remit following one or more attempts at treatment present a clinical challenge, as well as prolonged suffering and disability. Discouragement is common, so knowledge of likelihood of eventual remission as well as which treatments might ultimately be effective would help patient and clinician alike.

METHOD

Thirty-one patients with major depression were recruited, 28 beginning study treatment. All had remained significantly depressed following adequate (4 weeks taking ≥ PDR maximum dose) trials on ≥ two antidepressants having different presumed mechanisms. Patients were begun on tranylcypromine to 60 mg/d, were then treated with up to 120 mg/d and then had dextroamphetamine added. Following two week wash-out, patients were then treated with nortriptyline+lithium, and then phenelzine was added. Each successive phase was entered only if remission had not been achieved, and phases could be skipped.

RESULTS

Eighteen of the 28 patients (65%) remitted in one of the five phases of the study, plus 5 additional patients with open post-study treatment (total remitting, 82%). By study phase, Eight of 27 (30%) patients remitted with initial dosing of tranylcypromine up to 60 mg/d, 6/18 (33%) remitted with above PDR dosing of tranylcypromine up to 120 mg/d, and 1/6 (17%) to adding dextroamphetamine. With nortriptyline, 1/10 (10%) remitted with nortriptyline+lithium, and 1/5 (20%) when phenelzine was added. Eighteen of the 28 patients (64%), or 78% of those who remitted, maintained their good benefit for at least six months.

DISCUSSION

The majority of depressed patients refractory to two or more adequately utilized differently acting antidepressant medications can still remit and about half may maintain remission for extended periods. "Refractory depression" appears to be a relative description for many unresponsive depressed patients.

Relationships between computer-based testing and behavioral ratings in the assessment of attention and activity in a pediatric ADHD stimulant crossover trial

This study investigated the relationships between computer-based testing and behavioral ratings in the assessment of stimulant-induced changes in attention and activity in a pediatric ADHD crossover trial with methylphenidate, dextroamphetamine, and a placebo. Here 36 children between 9 and 14 years old were randomly and evenly assigned to each of six counterbalanced drug orders. A computer-based continuous performance test combined with a motion-tracking system (cb-CPT-MTS) and an ADHD questionnaire rated by teachers constituted the outcome measures. All outcome measures responded to stimulants in a comparable way at the group level, as shown by significant treatment effects of similar size for the two stimulants compared with a placebo. Computer-based and rating-based measures were unrelated in the assessment of stimulant-induced changes in attention and activity in individual children; no significant correlations between these measures in the assessment of change from placebo to stimulant conditions across the sample were detected. Results suggest that computer-based testing and behavioral ratings cannot be considered equivalent in the assessment of stimulant-induced changes in attention and activity among ADHD children.

Pharmacological treatment and demographic characteristics of pediatric patients with Attention Deficit Hyperactivity Disorder, Sweden

The aim of this study was to describe the pediatric population with ADHD and their pharmacological treatment. Using the Swedish National Patient Register and the Prescribed Drug Register we identified individuals below 19 years of age who were diagnosed or medically treated for ADHD for the first time 2006-2007. The unique patient identifiers were used to link information from the two registers to describe demographic characteristics, hospital care and drug treatments. Logistic regression model estimated the association between age, sex, frequency of hospitalization, diagnosis or treatment for other mental disorders and risk of gap in the treatment. Totally the study included 7931 patients of whom 74% were males. The mean age at first diagnosis was 12 years. Some 84% were medically treated for ADHD and approximately 90% received methylphenidate as the first substance. Combination therapy was rare and the most common combination was methylphenidate and atomoxetine. More than 55% of the patients, which could be followed up for two years after start of treatment, had at least one treatment gap of six months. Older age at diagnosis, lower number of hospitalizations and comorbidity with other mental disorders increased risks of gaps in medication. Approximately one fifth of the patients recorded in the National Patient Register as diagnosed with ADHD did not receive pharmacological treatment. Medication adherence seems to be low, when measured as gaps in treatment.

Monoaminergic dysfunction in recreational users of dexamphetamine

Preclinical studies suggest that dexamphetamine (dAMPH) can lead to monoaminergic neurotoxicity. This exploratory study aimed to investigate effects of recreational dAMPH use on the dopamine (DA) and noradrenaline (NA) systems in humans. To that purpose, eight male abstinent dAMPH (26.0 ± 4.0 years) users and 10 age- and IQ-matched male healthy control subjects (23.0 ± 3.8) underwent neuropsychological testing sensitive to DAergic function and single photon emission computed tomography (SPECT) scanning with [(123)I]FP-CIT to determine striatal DA transporter (DAT) binding. In addition, changes in cerebral blood flow (CBF) induced by the DA/NA reuptake inhibitor methylphenidate (MPH) were measured using pharmacological magnetic resonance imaging (phMRI). Performance of dAMPH users was significantly worse on executive function and verbal memory tasks. Striatal DAT binding ratios were on average lower in dAMPH users (near-significant, p=0.05). In addition, CBF in control subjects decreased significantly in response to MPH in gray matter and basal ganglia, among which the striatum, thalamus and hippocampus by 10% to 29%. However, in dAMPH users the CBF response was blunted in most brain areas studied, only decreasing in the hippocampus and orbitofrontal cortex. When comparing groups, CBF response was found to be significantly different in the thalamus with a decrease for healthy controls and a blunted response in dAMPH users. Collectively, our findings of a blunted hemodynamic response in monoaminergic regions, in combination with indications for lower striatal DAT binding and poorer behavioral measures are likely to represent DAergic dysfunction in dAMPH users, although NAergic dysfunction may also play a role.