Comparison of lisdexamfetamine and dextroamphetamine exposures reported to U.S. poison centers

Assessment of lisdexamfetamine on executive function in rats: A translational cognitive research

Executive function, including working memory, attention and inhibitory control, is crucial for decision making, thinking and planning. Lisdexamfetamine, the prodrug of d-amphetamine, has been approved for treating attention-deficit hyperactivity disorder and binge eating disorder, but whether it improves executive function under non-disease condition, as well as the underlying pharmacokinetic and neurochemical properties, remains unclear. Here, using trial unique non-matching to location task and five-choice serial reaction time task of rats, we found lisdexamfetamine (p.o) enhanced spatial working memory and sustained attention under various cognitive load conditions, while d-amphetamine (i.p) only improved these cognitive performances under certain high cognitive load condition. Additionally, lisdexamfetamine evoked less impulsivity than d-amphetamine, indicating lower adverse effect on inhibitory control. In vivo pharmacokinetics showed lisdexamfetamine produced a relative stable and lasting release of amphetamine base both in plasma and in brain tissue, whereas d-amphetamine injection elicited rapid increase and dramatical decrease in amphetamine base levels. Microdialysis revealed lisdexamfetamine caused lasting release of dopamine within the medial prefrontal cortex (mPFC), whereas d-amphetamine produced rapid increase followed by decline to dopamine level. Moreover, lisdexamfetamine elicited more obvious efflux of noradrenaline than that of d-amphetamine. The distinct neurochemical profiles may be partly attributed to the different action of two drugs to membranous catecholamine transporters level within mPFC, detecting by Western Blotting. Taken together, due to its certain pharmacokinetic and catecholamine releasing profiles, lisdexamfetamine produced better pharmacological action to improving executive function. Our finding provided valuable evidence on the ideal pharmacokinetic and neurochemical characteristics of amphetamine-type psychostimulants in cognition enhancement.

Prescription psychostimulants as a harm reduction and treatment intervention for methamphetamine use disorder and the implications for nursing clinical practice: A scoping review of the literature

The global rise in methamphetamine use and its negative effects warrants the need for research exploring harm reduction and treatment interventions for individuals with methamphetamine use disorder. Agonist medications have been utilized for years for the treatment of heroin and opioid addiction, but have yet to be incorporated into mainstream Canadian practice for methamphetamine dependence. This review aims to provide an overview of the current trends of prescription psychostimulant usage for individuals with methamphetamine use disorder from a Canadian perspective, identifies the barriers to accessing prescription psychostimulants for methamphetamine use disorder and highlights the nursing clinical practice implications in caring for individuals with the disorder. Discourse on the sustained abstinence and harm reduction debate is presented from the perspective of methamphetamine abuse is provided along with the neuropsychiatric complications of chronic methamphetamine use. The impacts of specific prescription psychostimulants on cognition are discussed as is the use of neuroimaging techniques to assess neuronal damage in methamphetamine users. Sign of toxicity, overdose and the contraindications for use of these prescription psychostimulants is also presented. The implications to nursing clinical practice in caring for this population is provided, touching on the clinical presentation of methamphetamine use, completing thorough assessment and screening and patient education. The findings of this review indicate the need for further research in this area exploring the benefits of prescription psychostimulants as a harm reduction and treatment intervention for the global problem of methamphetamine dependence.

Cannabis and Other Substance Misuse: Implications and Regulations

Abusing controlled substances, including cannabis and various drugs, can result in severe intoxication and even death. Therefore, a comprehensive postmortem analysis is crucial for understanding the underlying causes of such fatalities. This narrative review discusses the characteristics of commonly abused controlled substances, the methodologies employed in postmortem analysis, lethal dosage levels, mechanisms of toxicity, side effects, and existing regulations. The focus centers on seven prevalent groups of controlled substances, namely cannabis, opioids, amphetamine-type stimulants, cocaine, new psychoactive substances, and hallucinogens. These groups have been linked to an increased risk of fatal overdose. Most substances in these groups exert neurotoxic effects by targeting the central nervous system (CNS). Consequently, strict regulation is essential to mitigate the potential harm posed by these substances. To combat abuse, prescribers must adhere to guidelines to ensure their prescribed medications comply with the outlined regulations. Through an enhanced understanding of controlled substance abuse and its consequences, more effective strategies can be developed to reduce its prevalence and associated mortality.

Prescription psychostimulants for cocaine use disorder: A review from molecular basis to clinical approach

Cocaine use is a public health concern in many countries worldwide, particularly in the Americas and Oceania. Overdose deaths involving stimulants, such as cocaine, have been increasing markedly in North America, especially with concurrent opioid involvement. To date, no pharmacological treatment is available to treat stimulant (including cocaine) use disorders. Prescription psychostimulants (PPs) could be useful to treat cocaine use disorder (CUD) as they share the pharmacological effects with cocaine, as evidenced by a recent meta-analysis that assessed 38 randomized clinical trials (RCTs). PPs were found to promote sustained abstinence and reduce drug use in patients with CUD. The aim of this paper is to provide a narrative review of the clinical pharmacology of PPs and comment on the current stage of evidence supporting PPs to treat CUD. We also propose a model of care that integrates PPs with evidence-based psychosocial interventions (such as cognitive-behavioural therapy [CBT] and contingency management [CM]), a harm reduction approach and case management with social support.

What is the potential for abuse of lisdexamfetamine in adults? A preclinical and clinical literature review and expert opinion

INTRODUCTION

: Lisdexamfetamine dimesylate (LDX) is a prodrug approved for attention deficit/hyperactivity disorder and for moderate-to-severe binge eating disorder in adults in some countries.

AREA COVERED

: We aimed to specify the abuse potential of LDX in adults, using a review of pharmacokinetic/pharmacodynamic (PK/PD), animal, clinical, and pharmaco-epidemiological studies, through a PubMed search since inception until May 2021 using the following keywords: "lisdexamfetamine AND ("misuse" OR "abuse" OR "diversion" OR "addiction").

EXPERT OPINION

: Most of the studies highlighted a longer T_max than dexamphetamine leading to a delayed onset of effects and a decreased C_max. These PK parameters were often associated with a diminished feeling of euphoria, in comparison to immediate-release dexamphetamine. The potential for abuse was also limited by the prodrug property of LDX, thus reducing the risk of misuse. Nevertheless, all the data were not convergent, as some authors reported similar C_max for LDX and dexamphetamine and reinforcing properties with a dose-dependent effect. Epidemiological studies found that abuse rates of LDX were substantially lower than those of immediate-release dexamphetamine. Overall, although LDX abuse seems possible, we did not find evidence concerning current safety signal. However, more long-term pharmaco-epidemiological studies are still needed to confirm this finding.

Rise, and pronounced regional variation, in methylphenidate, amphetamine, and lisdexamfetamine distribution in the United States

Background

The prescription stimulants methylphenidate, amphetamine, and lisdexamfetamine are sympathomimetic drugs with therapeutic use. They are designated in the United States as Schedule II substances, defined by the 1970 Controlled Substances Act as having a “high potential for abuse”. Changing criteria for the diagnosis of Attention Deficit Hyperactivity Disorder in 2013 and the approval of lisdexamfetamine for binge eating disorder in 2015 may have impacted usage patterns. This report compared the pharmacoepidemiology of these stimulants in the United States from 2010–2017.

Methods

Distribution of amphetamine, methylphenidate, lisdexamfetamine were examined via weights extracted from the Drug Enforcement Administration’s (DEA) Automated Reports and Consolidated Ordering System (ARCOS). Median stimulant Daily Dosage per patient was determined for a regional analysis. The percent of cost and prescriptions attributable to each stimulant and atomoxetine in Medicaid from the “Drug Utilization 2018 - National Total” from the Centers for Medicare and Medicaid was determined.

Results

There was a rise in amphetamine (+67.5%) and lisdexamfetamine (+76.7%) from 2010–2017. The change in methylphenidate (−3.0%) was modest. Persons/day stimulant usage was lower in the West than in other US regions from 2014-2017. There was a negative correlation (r(48) = −0.43 to −0.65, p < .05) between the percent Hispanic population per state and the Daily Dosage/population per stimulant. Methylphenidate formulations accounted for over half (51.7%) of the $3.8 billion reimbursed by Medicaid and the plurality (45.4%) of the 22.0 million prescriptions. Amphetamine was responsible for less than one-fifth (18.4%) of cost but one-third of prescriptions (33.6%). Lisdexamfetamine’s cost (26.0%) exceeded prescriptions (16.3%).

Conclusion

The rising amphetamine and lisdexamfetamine distribution may correspond with a rise in adult ADHD diagnoses. Regional analysis indicates that stimulant distribution in the West may be distinct from that in other regions. The lower stimulant distribution in areas with greater Hispanic populations may warrant further study.

Hypoglycemia and presumptive rhabdomyolysis secondary to lisdexamfetamine toxicosis in 3 cats

OBJECTIVE

To describe the clinical course and novel biochemical changes in 3 cats with lisdexamfetamine (LDX) toxicosis.

SERIES SUMMARY

Three cats presented with LDX exposure and initially displayed typical clinical signs of amphetamine toxicosis. However, over the course of hospitalization, hypoglycemia and markedly elevated creatine kinase levels consistent with rhabdomyolysis ensued. All cats were treated with sedatives including phenothiazines and dexmedetomidine. Two cats were hospitalized for 4 days and 1 for 5 days. All cats survived.

NEW OR UNIQUE INFORMATION PROVIDED

This is the first case series in cats that reports the novel biochemical changes of delayed hypoglycemia and elevated creatine kinase several days into hospitalization for the treatment of LDX toxicity. The development of delayed clinical signs suggests reconsideration of established hospitalization guidelines for amphetamine ingestion in cats.

Converging vulnerability factors for compulsive food and drug use

Highly palatable foods and substance of abuse have intersecting neurobiological, metabolic and behavioral effects relevant for understanding vulnerability to conditions related to food (e.g., obesity, binge eating disorder) and drug (e.g., substance use disorder) misuse. Here, we review data from animal models, clinical populations and epidemiological evidence in behavioral, genetic, pathophysiologic and therapeutic domains. Results suggest that consumption of highly palatable food and drugs of abuse both impact and conversely are regulated by metabolic hormones and metabolic status. Palatable foods high in fat and/or sugar can elicit adaptation in brain reward and withdrawal circuitry akin to substances of abuse. Intake of or withdrawal from palatable food can impact behavioral sensitivity to drugs of abuse and vice versa. A robust literature suggests common substrates and roles for negative reinforcement, negative affect, negative urgency, and impulse control deficits, with both highly palatable foods and substances of abuse. Candidate genetic risk loci shared by obesity and alcohol use disorders have been identified in molecules classically associated with both metabolic and motivational functions. Finally, certain drugs may have overlapping therapeutic potential to treat obesity, diabetes, binge-related eating disorders and substance use disorders. Taken together, data are consistent with the hypotheses that compulsive food and substance use share overlapping, interacting substrates at neurobiological and metabolic levels and that motivated behavior associated with feeding or substance use might constitute vulnerability factors for one another. This article is part of the special issue on 'Vulnerabilities to Substance Abuse'.

Review of lisdexamfetamine dimesylate in children and adolescents with attention deficit/hyperactivity disorder

OBJECTIVE

Lisdexamfetamine dimesylate is a stimulant prodrug with low abuse and diversion potential that is used in treatment of attention deficit hyperactivity disorder (ADHD) in children, adolescents and adults. This current literature review article aims to examine safety and efficacy of LDX in children and adolescents for the treatment of ADHD based on currently available data.

METHODS

Relevant English language articles were identified through computerized searches of the MEDLINE database (PubMed and EMBASE) and clinical trials registry up to January 2020 using the following search terms: lisdexamfetamine dimesylate, pro-drug stimulant, attention-deficit and hyperactivity disorders, ADHD, safety, efficacy, children, adolescents, Vyvanse. Forty-two articles were reviewed, 34 of which were included into this review, selected by the limit "clinical trials". This article represents the pharmacological profile, efficacy and safety data of LDX for the treatment of ADHD in children and adolescents.

RESULTS

The collection of studies reviewed identified that LDX was both safe and efficacious in the treatment of ADHD. The most commonly exhibited side effects were appetite suppression, weight loss, headache and insomnia. In comparison to placebo, LDX significantly improved ADHD symptoms and overall quality of life in children and adolescents. In comparison to atomoxetine, LDX showed statistically significant improvements in inattention, impulsivity, and activities of daily living. In comparison to OROS-MPH and placebo, LDX and OROS-MPH showed improvements with the CGI-I score, and ADHD-RS-IV, however, LDX was superior.

CONCLUSION

Patients have seen statistically significant improvements in their ADHD symptomatology in the classroom environment, health related quality of life, and their overall behavior in comparison to placebo, atomoxetine, and OROS-MPH. However, clinical judgment should be utilized when prescribing LDX due to patient specific needs and the side effect profile.

Accidental intoxications in toddlers: lack of cross-reactivity of vilazodone and its urinary metabolite M17 with drug of abuse screening immunoassays

Background

Vilazodone is an FDA approved medication used to treat major depressive disorder. The authors describe two cases of accidental vilazodone exposure in toddlers who presented with symptoms similar to amphetamine exposure and also with unexplained positive amphetamine urine immunoassay drug screens. Given a lack of published data on cross-reactivity of vilazodone and its metabolites with drug of abuse screening tests, the authors investigated drug of abuse immunoassay cross-reactivity of vilazodone and metabolites using computational and empirical approaches.

Methods

To ascertain the likelihood that vilazodone would cross-react with drug of abuse screening immunoassays, the authors assessed the two-dimensional (2D) similarity of the vilazodone parent molecule and known metabolites to an array of antigenic targets for urine immunoassay drug screens. To facilitate studies of the commercially unavailable M17 metabolite, it was prepared synthetically through a novel scheme. Urine and serum were spiked with vilazodone and M17 into urine (200–100,000 ng/mL) and serum (20–2000 ng/mL) samples and tested for cross-reactivity.

Results

Computational analysis using 2D similarity showed that vilazodone and metabolites have generally low similarity to antigenic targets of common drug of abuse screening immunoassays, predicting weak or no cross-reactivity. The M17 metabolite had 2D similarity to amphetamines and tricyclic antidepressants in a range similar to some other compounds exhibiting weak cross-reactivity on these immunoassays. Cross-reactivity testing was therefore performed on two different urine amphetamines immunoassays and a serum tricyclic antidepressant immunoassay. However, actual testing of cross reactivity for vilazodone and the M17 metabolite did not detect cross-reactivity for any urine amphetamines screen at concentrations up to 100,000 ng/mL and for a serum tricyclic antidepressants assays at concentrations up to 2000 ng/mL.

Conclusion

While the vilazodone metabolite M17 has weak 2D structural similarity to amphetamines and tricyclic antidepressants, the current study did not demonstrate any experimental cross-reactivity with two different urine amphetamines immunoassays and a serum tricyclic antidepressant immunoassay. Vilazodone ingestions in young children present a diagnostic challenge in their similarity to amphetamine ingestions and the lack of routine laboratory tests for vilazodone. Further work is needed to understand the metabolic profile for vilazodone in children versus adults.

Electronic supplementary material

The online version of this article (10.1186/s12907-019-0084-9) contains supplementary material, which is available to authorized users.

Effects of lisdexamfetamine on plasma steroid concentrations compared with d-amphetamine in healthy subjects: A randomized, double-blind, placebo-controlled study

The novel d-amphetamine prodrug lisdexamfetamine is applied to treat attention-deficit/hyperactivity disorder (ADHD). d-Amphetamine releases dopamine and norepinephrine and stimulates the hypothalamic-pituitary-adrenal (HPA) axis, which may contribute to its reinforcing effects and risk of abuse. However, no data is currently available on the effects of lisdexamfetamine on circulating steroids. This randomized, double-blind, placebo-controlled, cross-over study evaluated the effects of equimolar doses of d-amphetamine (40 mg) and lisdexamfetamine (100 mg) and placebo on circulating steroids in 24 healthy subjects. Plasma steroid and d-amphetamine levels were determined up to 24 h. Delayed increase and peak levels of plasma d-amphetamine concentrations were observed following lisdexamfetamine treatment compared with d-amphetamine administration, however the maximal concentrations and total exposure (area under the curve [AUC]) were similar. Lisdexamfetamine and d-amphetamine significantly enhanced plasma levels of adrenocorticotropic hormone, glucocorticoids (cortisol, cortisone, corticosterone, 11-dehydrocorticosterone, and 11-deoxycortisol), androgens (dehydroepiandrosterone, dehydroepiandrosterone sulfate, and Δ4-androstene-3,17-dione [androstenedione]), and progesterone (only in men) compared with placebo. Steroid concentration-time curves were shifted to later time points due to a non-significantly later onset following lisdexamfetamine administration than after d-amphetamine, however maximal plasma steroid concentrations and AUCs did not differ between the active treatments. None of the active treatments altered plasma levels of the mineralocorticoids aldosterone and 11-deoxycorticosterone or the androgen testosterone compared with placebo. The effects of the amphetamines on glucocorticoid production were similar to those that were previously reported for methylphenidate (60 mg) but weaker than those for the serotonin releaser 3,4-methylenedioxymethamphetamine (MDMA; 125 mg) or direct serotonin receptor agonist lysergic acid diethylamide (LSD; 0.2 mg). Lisdexamfetamine produced comparable HPA axis activation and had similar pharmacokinetics than d-amphetamine, except for a delayed time of onset. Thus, serotonin (MDMA, LSD) may more effectively stimulate the HPA axis than dopamine and norepinephrine (D-amphetamine).

Trends in use of prescription stimulants in the United States and Territories, 2006 to 2016

BACKGROUND

Stimulants are considered the first-line treatment for Attention Deficit Hyperactivity Disorder (ADHD) in the US and they are used in other indications. Stimulants are also diverted for non-medical purposes. Ethnic and regional differences in ADHD diagnosis and in stimulant use have been identified in earlier research. The objectives of this report were to examine the pharmacoepidemiological pattern of these controlled substances over the past decade and to conduct a regional analysis.

METHODS

Data (drug weights) reported to the US Drug Enforcement Administration's Automation of Reports and Consolidated Orders System for four stimulants (amphetamine, methylphenidate, lisdexamfetamine, and methamphetamine) were obtained from 2006 to 2016 for Unites States/Territories. Correlations between state level use (mg/person) and Hispanic population were completed.

RESULTS

Amphetamine use increased 2.5 fold from 2006 to 2016 (7.9 to 20.0 tons). Methylphenidate use, at 16.5 tons in 2006, peaked in 2012 (19.4 tons) and subsequently showed a modest decline (18.6 tons in 2016). The consumption per municipality significantly increased 7.6% for amphetamine and 5.5% for lisdexamfetamine but decreased 2.7% for methylphenidate (all p < .0005) from 2015 to 2016. Pronounced regional differences were also observed. Lisdexamfetamine use in 2016 was over thirty-fold higher in the Southern US (43.8 mg/person) versus the Territories (1.4 mg/person). Amphetamine use was about one-third lower in the West (48.1 mg/person) relative to the Northeastern (75.4 mg/person, p < .05) or the Midwestern (69.9 mg/person, p ≤ .005) states. States with larger Hispanic populations had significantly lower methylphenidate (r(49) = -0.63), lisdexamfetamine (B, r(49) = -0.49), and amphetamine (r(49) = -0.43) use.

CONCLUSIONS

Total stimulant usage doubled in the last decade. There were dynamic changes but also regional disparities in the use of stimulant medications. Future research is needed to better understand the reasons for the sizable regional and ethnic variations in use of these controlled substances.

A case series involving young children presenting with accidental ingestion of amphetamine based stimulants

•

Attention Deficity Hyperactivity Disorder (ADHD) affects adults and children.

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Stimulant prescribing for ADHD is increasing.

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Overdose of amphetamine based stimulants results in a sympathomimetic toxidrome.

•

Lisdexamfetamine dimesylate is the first prodrug stimulant developed to treat ADHD.

Pediatric ADHD Medication Exposures Reported to US Poison Control Centers

: media-1vid110.1542/5754332180001PEDS-VA_2017-3872Video Abstract OBJECTIVES: To describe the characteristics and trends of exposures to attention-deficit/hyperactivity disorder (ADHD) medications among individuals 0 to 19 years old reported to US poison control centers.

METHODS

National Poison Data System data from 2000 through 2014 were retrospectively analyzed to examine pediatric ADHD medication exposures.

RESULTS

From 2000 through 2014, there were 156 365 exposures reported to US poison control centers related to ADHD medications. The overall rate of reported exposures increased 71.2% from 2000 to 2011, followed by a 6.2% decrease from 2011 to 2014. Three-fourths (76.0%) of exposures involved children ≤12 years old. Methylphenidate and amphetamine medications accounted for 46.2% and 44.5% of exposures, respectively. The most common reason for exposure was therapeutic error (41.6%). Intentional medication exposures (including suspected suicide and medication abuse and/or misuse) were reported most often among adolescents (13-19 years old), accounting for 50.2% of exposures in this age group. Overall, the majority of exposed individuals (60.4%) did not receive health care facility treatment; however, 6.2% were admitted to a hospital for medical treatment, and there were 3 deaths. The increasing number and rate of reported ADHD medication exposures during the study period is consistent with increasing trends in ADHD diagnosis and medication prescribing. Exposures associated with suspected suicide or medication abuse and/or misuse among adolescents are of particular concern.

CONCLUSIONS

Unintentional and intentional pediatric exposures to ADHD medications are an increasing problem in the United States, affecting children of all ages.

Acute effects of lisdexamfetamine and D-amphetamine on social cognition and cognitive performance in a placebo-controlled study in healthy subjects

RATIONALE

Amphetamines are used as medications but are also misused as cognitive enhancers by healthy subjects and may have additional effects on social cognition.

METHODS

We investigated the acute effects of single, high, equimolar doses of D-amphetamine (40 mg) and lisdexamfetamine (100 mg) on social cognition and cognitive performance using a randomized, placebo-controlled, double-blind, cross-over design in 24 healthy volunteers. Effects on social cognition were assessed using the Facial Emotion Recognition Task (FERT), Multifaceted Empathy Test (MET), and Sexual Arousal Task (SAT). Cognitive performance was measured using the Digit Symbol Substitution Test (DSST), Digit Span (DS), Stop-Signal Task (SST), and Mackworth Clock Test (MCT).

RESULTS

D-Amphetamine and lisdexamfetamine had small effects on measures of social cognition. There were no effects on emotion recognition on the FERT. D-Amphetamine increased direct empathy on the MET, but only for positive stimuli. Both amphetamines increased ratings of pleasantness and attractiveness on the SAT in response to sexual but also to neutral stimuli. D-Amphetamine and lisdexamfetamine increased cognitive performance (go-accuracy and vigilance on the SST and MCT, respectively). Lisdexamfetamine increased processing speed on the DSST. Neither drug had an effect on the DS.

CONCLUSION

Single, high, equimolar doses of D-amphetamine and lisdexamfetamine enhanced certain aspects of cognitive performance in healthy non-sleep-deprived subjects. Both amphetamines also slightly altered aspects of social cognition. Whether these small effects also influence social interaction behavior in amphetamine users remains to be investigated.

TRIAL REGISTRATION

The study was registered at ClinicalTrials.gov (NCT02668926).

E-Cigarette and Liquid Nicotine Exposures Among Young Children

OBJECTIVES

To investigate exposures to liquid nicotine (including electronic cigarette devices and liquids) among children <6 years old in the United States and evaluate the impact of legislation requiring child-resistant packaging for liquid nicotine containers.

METHODS

Liquid nicotine exposure data from the National Poison Data System for January 2012 through April 2017 were analyzed.

RESULTS

There were 8269 liquid nicotine exposures among children <6 years old reported to US poison control centers during the study period. Most (92.5%) children were exposed through ingestion and 83.9% were children <3 years old. Among children exposed to liquid nicotine, 35.1% were treated and released from a health care facility, and 1.4% were admitted. The annual exposure rate per 100 000 children increased by 1398.2% from 0.7 in 2012 to 10.4 in 2015, and subsequently decreased by 19.8% from 2015 to 8.3 in 2016. Among states without a preexisting law requiring child-resistant packaging for liquid nicotine containers, there was a significant decrease in the mean number of exposures during the 9 months before compared with the 9 months after the federal child-resistant packaging law went into effect, averaging 4.4 (95% confidence interval: -7.1 to -1.7) fewer exposures per state after implementation of the law.

CONCLUSIONS

Pediatric exposures to liquid nicotine have decreased since January 2015, which may, in part, be attributable to legislation requiring child-resistant packaging and greater public awareness of risks associated with electronic cigarette products. Liquid nicotine continues to pose a serious risk for young children. Additional regulation of these products is warranted.

Pediatric Pharmaceutical Ingestions

Pharmaceutical ingestions comprise an important part of pediatric toxicology. Based on the 2015 Annual Report of the American Association of Poison Control Centers' National Poison Data System, coupled with recent epidemiology articles on the topic of pediatric toxicology, it is apparent that poison prevention education has not been completely successful in decreasing exposures to toxic drugs. From the unintentional ingestion in a toddler due to unsafe storage to the intentional adolescent ingestion for misuse and abuse, pharmaceutical medications continue to cause harm. Access to adult prescription drugs in the home accounted for most of the exposures in children age ≤5 years as well as adolescents age 13 to 19 years. Ingestions resulting from more common pharmaceutical exposures are discussed with the hope of increasing awareness about the need for added vigilance. [Pediatr Ann. 2017;46(12):e459-e465.].

Pharmacokinetics and Pharmacodynamics of Lisdexamfetamine Compared with D-Amphetamine in Healthy Subjects

Rationale: Lisdexamfetamine is a prodrug of D-amphetamine used for the treatment of attention-deficit/hyperactivity disorder (ADHD). Lisdexamfetamine is thought to have a prolonged pharmacokinetic profile compared with oral D-amphetamine, possibly associated with lower drug liking and a lower risk of oral misuse. However, differences in the pharmacokinetics and pharmacodynamics of lisdexamfetamine and D-amphetamine have not been directly compared. Methods: Equimolar doses of D-amphetamine (40 mg) and lisdexamfetamine (100 mg), and placebo were administered in 24 healthy subjects in a randomized, double-blind, placebo-controlled, cross-over study. Plasma concentrations of amphetamine, subjective effects, and vital signs were repeatedly assessed. The pharmacokinetic parameters were determined using compartmental modeling. Results: The increase in plasma concentrations of amphetamine had a 0.6 ± 0.6 h (mean ± SD) longer lag time and reached peak levels 1.1 ± 1.5 h later after lisdexamfetamine administration compared with D-amphetamine administration, but no differences in maximal concentrations or total exposure (AUC) were found between the two treatments. Consistent with the pharmacokinetics, the subjective and cardiovascular stimulant effects of lisdexamfetamine also occurred later compared with D-amphetamine. However, no differences in peak ratings of potentially abuse-related subjective drug effects (e.g., drug liking, drug high, stimulation, happy, well-being, and self-confidence) were observed after lisdexamfetamine administration compared with D-amphetamine administration. Lisdexamfetamine and D-amphetamine also produced similar peak increases in mean arterial blood pressure, heart rate, body temperature, pupil size, and adverse effects. Conclusion: The pharmacokinetics and pharmacodynamics of lisdexamfetamine are similar to D-amphetamine administered 1h later. Lisdexamfetamine is likely associated with a similar risk of oral abuse as D-amphetamine. The study was registered at ClinicalTrials.gov (NCT02668926).

The safety of extended-release drug formulations for the treatment of ADHD

INTRODUCTION

Attention-deficit/hyperactivity disorder (ADHD) is a complex neurobehavioral disorder affecting millions of patients worldwide. Effective treatments have been available for more than 60 years in the form of immediate-release (IR) stimulants However, stimulants have a high risk for abuse and are associated with adverse effects Including elevated blood pressure and heart rate, insomnia and decreased appetite. IR formulations also require multiple daily dosing. The search for improved safety, tolerability and convenience has led to the development of multiple extended-release (ER) stimulant and non-stimulant formulations. Areas covered: Adverse effects of (ER) products including amphetamine, methylphenidate, clonidine and guanfacine will be reviewed and their significance discussed. Expert opinion: Limitations of currently marketed medications have led to the search for drugs with efficacy comparable to ER stimulants and a more favorable adverse event profile. Several are in development, but their potential utility is not yet known. Current research is also focused on finding specific genetic defects in patients with ADHD. Exciting progress has been made with the identification of mGluR receptor defects in some patients. However because of the heterogeneity of the disorder, effective targeted treatments for the majority of patients with ADHD does not appear likely in the near future.

Lisdexamfetamine Dimesylate: Prodrug Delivery, Amphetamine Exposure and Duration of Efficacy

Lisdexamfetamine dimesylate (LDX) is a long-acting d-amphetamine prodrug used to treat attention-deficit/hyperactivity disorder (ADHD) in children, adolescents and adults. LDX is hydrolysed in the blood to yield d-amphetamine, and the pharmacokinetic profile of d-amphetamine following oral administration of LDX has a lower maximum plasma concentration (C_max), extended time to C_max (T_max) and lower inter- and intra-individual variability in exposure compared with the pharmacokinetic profile of an equivalent dose of immediate-release (IR) d-amphetamine. The therapeutic action of LDX extends to at least 13 h post-dose in children and 14 h post-dose in adults, longer than that reported for any other long-acting formulation. Drug-liking scores for LDX are lower than for an equivalent dose of IR d-amphetamine, which may result from the reduced euphorigenic potential associated with its pharmacokinetic profile. These pharmacokinetic and pharmacodynamic characteristics of LDX may be beneficial in the management of symptoms in children, adolescents and adults with ADHD.

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.

Attenuation of cocaine self-administration by chronic oral phendimetrazine in rhesus monkeys

Chronic treatment with the monoamine releaser d-amphetamine has been consistently shown to decrease cocaine self-administration in laboratory studies and clinical trials. However, the abuse potential of d-amphetamine is an obstacle to widespread clinical use. Approaches are needed that exploit the efficacy of the agonist approach but avoid the abuse potential associated with dopamine releasers. The present study assessed the effectiveness of chronic oral administration of phendimetrazine (PDM), a pro-drug for the monoamine releaser phenmetrazine (PM), to decrease cocaine self-administration in four rhesus monkeys. Each day, monkeys pressed a lever to receive food pellets under a 50-response fixed-ratio (FR) schedule of reinforcement and self-administered cocaine (0.003-0.56 mg/kg per injection, i.v.) under a progressive-ratio (PR) schedule in the evening. After completing a cocaine self-administration dose-response curve, sessions were suspended and PDM was administered (1.0-9.0 mg/kg, p.o., b.i.d.). Cocaine self-administration was assessed using the PR schedule once every 7 days while food-maintained responding was studied daily. When a persistent decrease in self-administration was observed, the cocaine dose-effect curve was re-determined. Daily PDM treatment decreased cocaine self-administration by 30-90% across monkeys for at least 4 weeks. In two monkeys, effects were completely selective for cocaine. Tolerance developed to initial decreases in food-maintained responding in the third monkey and in the fourth subject, fluctuations were observed that were lower in magnitude than effects on cocaine self-administration. Cocaine dose-effect curves were shifted down and/or rightward in three monkeys. These data provide further support for the use of agonist medications for cocaine abuse, and indicate that the promising effects of d-amphetamine extend to a more clinically viable pharmacotherapy.