A placebo-controlled, fixed-dose study of aripiprazole in children and adolescents with irritability associated with autistic disorder

Issues in the management of challenging behaviours of adults with autism spectrum disorder

Autism spectrum disorder (ASD) is a particularly important risk factor for challenging behaviours such as aggression, tantrums, self-injury and pica. Adults with ASD have rarely been studied with respect to these problems. This is particularly disconcerting since there are far more adults than children with ASD. In addition, because of adults' increased physical size and longer history of these problems, treating these behaviours effectively is important. Psychological methods, particularly applied behaviour analysis, and pharmacotherapy have been the most frequently addressed treatments for challenging behaviours associated with ASD in the research literature. In many cases, challenging behaviours have clear environmental antecedents. In these cases, behavioural interventions, such as applied behaviour analysis, should be used to reduce the behaviours. When environmental factors cannot be identified or when challenging behaviours are very severe, pharmacological treatments may be necessary in combination with behavioural interventions. Newer antipsychotics are the most researched medications for use with this population. Currently, risperidone and aripiprazole are the only medications that have US FDA approval for the treatment of behaviours associated with ASD, specifically irritability; however, they are indicated for use in children not adults. It is important not to use medications unnecessarily, due to possible side effects associated with their use. Based on available research, some recommendations for the treatment of challenging behaviours of adults (and children) with ASD include the use of functional assessment, side-effect monitoring of medications and behavioural methods whenever possible. Additionally, future research in this area needs to focus more on adults, as most current research has used child samples.

Treatment strategies for dosing the second generation antipsychotics

BACKGROUND

The second generation antipsychotics now have clinical approvals for the treatment of schizophrenia, bipolar depression, bipolar mania, autism, major depressive disorder and are used furthermore off-label to treat other mental disorders. Each agent is unique in its pharmacodynamic profile and allows for unique dosing strategies to be employed when treating these different disorders.

AIMS

To review relevant data regarding the second generation antipsychotics and their empirical dosing strategies. To further review and comment theoretically in these areas where substantial, definitive data are lacking.

MATERIALS AND METHODS

A MEDLINE and recent textbook review was conducted regarding each second generation antipsychotic and cross-referenced with searches for major mental disorders. The findings are compiled in the review below.

DISCUSSION

The second generation antipsychotics are clearly delineated in the treatment of psychosis and mania and share similar mechanisms of action to achieve these results: dopamine-2 receptor antagonism for efficacy and serotonin-2a receptor antagonism for EPS tolerability. From here, each agent has a unique pharmacodynamic and pharmacokinetic profile where some agents carry more, or less antidepressant, anxiolyic, or hypnotic profiles. Choosing an agent, and dosing it in low, middle, or high ranges may result in differential effectiveness and tolerability.

CONCLUSION

The second generation antipsychotics have many clinical applications in psychiatric practice. This article serves to review this and also suggests ways clinicians may optimize treatment based upon patient diagnosis and utilizing appropriate dosing of each individual second generation antipsychotic.

Nature and quality of antipsychotic prescribing practice in UK psychiatry of intellectual disability services

BACKGROUND

Antipsychotics are perceived to be over-used in the management of behavioural problems in people with an intellectual disability (ID). Published guidelines have set good practice standards for the use of these drugs for behavioural indications. We sought to identify the range of indications for which antipsychotic drugs are prescribed in people with ID and to audit clinical practice against the standards.

METHOD

Data were collected from the clinical records of individuals with ID who were under the care of mental health services in the UK, and prescribed an antipsychotic drug.

RESULTS

The sample comprised 2319 patients from 39 clinical services. Twenty-seven per cent of the patients had a diagnosis of a psychotic illness (ICD-10 F20-29) and 27% an affective illness (ICD-10 F30-39). The proportion who did not have a psychiatric diagnosis ranged from 6% of those with borderline/mild ID to 21% of those with severe/profound ID. Overall, the most common indications for prescribing an antipsychotic drug were comorbid psychotic illness, anxiety and agitation, and a range of behavioural disturbances. The prevalence of use of antipsychotic drugs to manage challenging behaviour in the absence of concomitant mental illness increased with the severity of ID and accounted for almost half of prescriptions in those with severe/profound ID. Adherence to the audit standards related to documentation of clinical indications and review of efficacy was high. Side effect monitoring was less assiduous.

CONCLUSIONS

In clinical practice, most prescriptions for antipsychotic drugs in people with ID are consistent with the evidence base and the overall quality of prescribing practice, as measured against recognised standards, is good, although in some patients potentially remedial side effects may not be detected and treated.

Aripiprazole: a review of its use in the treatment of irritability associated with autistic disorder patients aged 6-17

A systematic review and meta-analysis were performed examining the efficacy of aripiprazole for the treatment of irritability associated with autistic disorder in children and adolescents. Aripiprazole was found to be more effective in reducing irritability compared with placebo at 8 weeks, SMD −0.64 [−0.90 to −0.39, P < 0.00001] as determined by the Aberrant Behaviour Checklist irritability subscale (ABC-I). Pooled data from two eight week trials show that sedation is the most commonly reported adverse event. Statistically significant weight gain was also associated with aripiprazole, but there was a decrease in serum prolactin. Most adverse effects were deemed to be mild to moderate in severity. Four open trials and three case series all show support for aripiprazole in reducing the behavioural symptoms of autism. Long-term studies are required to determine the efficacy and safety of aripiprazole in autistic disorder in children.

[Aripiprazole use in children and adolescent psychiatric patients]

Aripiprazole inaugurates a new generation of antipsychotics called dopamine-serotonin system stabilizers. Its mechanism of action is different as aripiprazole is a partial dopamine D(2) and serotonin 5-HT(1A) receptor agonist and 5-HT(2A) receptor antagonist. Therefore, aripiprazole is thought to have an antagonistic action in the mesolimbic pathway but an agonistic action in the mesocortical pathway, tending to normalize the dopaminergic transmission regardless of the type of imbalance. Clinical trials involving children and adolescents have demonstrated the efficacy of aripiprazole in bipolar disorders, schizophrenia, mood disorders associated with pervasive developmental disorders, in tics and Tourette's. The most frequent side effects are extrapyramidal symptoms and sleepiness and are dose-dependent. Nevertheless, contrary to other second-generation antipsychotics available in France, it induces little weight gain, does not modify lipid and glucidic profiles, does not increase prolactin levels, or induce QTc lengthening. The main advantage of aripiprazole is its good safety profile, with different toxicity targets to other second-generation antipsychotics available in France. Aripiprazole appears to be an alternative for children and adolescents who are vulnerable to these side effects and are having trouble coping with them.

Aripiprazole in the treatment of irritability in pediatric patients (aged 6-17 years) with autistic disorder: results from a 52-week, open-label study

AIM

To report the long-term efficacy of aripiprazole in the treatment of irritability in children and adolescents (ages 6-17 years) with autistic disorder.

METHODS

This was a 52-week, open-label, flexible-dose (2-15 mg/day) study of aripiprazole for the treatment of children and adolescents with irritability associated with autistic disorder. Eligible subjects were enrolled from two 8-week randomized trials or were enrolled as de novo subjects. "Prior aripiprazole" subjects had received treatment with aripiprazole for 8 weeks before entering this study. Evaluation of efficacy, a secondary objective after evaluation of safety and tolerability in this study, was conducted using the caregiver-rated Aberrant Behavior Checklist-Irritability subscale and the clinician-rated Clinical Global Impression-Improvement score.

RESULTS

Three hundred thirty subjects received treatment (de novo, n = 86; prior aripiprazole, n = 174; prior placebo, n = 70) and 199 subjects (60.3%) completed 52 weeks of treatment. At their last study visit, 38.2% of subjects were receiving concomitant central nervous system medications (commonly antidepressants, 13.4%; psychostimulants, 11.5%; antiepileptics, 5.9%). At week 52 (observed cases data set), the mean change from baseline in Aberrant Behavior Checklist Irritability subscale scores was -8.0 in de novo subjects and -6.1 in prior placebo subjects; prior aripiprazole subjects maintained symptom improvement that was achieved with treatment in the prior study. At endpoint, the majority of subjects had a Clinical Global Impressions-Improvement score of 2 (much improved) or 1 (very much improved).

CONCLUSION

Aripiprazole reduced symptoms of irritability associated with autistic disorder in pediatric subjects ages 6-17 years who were studied for up to 1 year.

Aripiprazole: in the treatment of irritability associated with autistic disorder in pediatric patients

Aripiprazole is an atypical antipsychotic approved for the treatment of irritability associated with autistic disorder in pediatric patients aged 6-17 years. In two, randomized, double-blind, placebo-controlled studies in pediatric patients aged 6-17 years with irritability associated with autistic disorder, 8 weeks of treatment with aripiprazole 2-15 mg/day, compared with placebo, resulted in significant improvements in the Aberrant Behavior Checklist Irritability subscale score at endpoint (primary endpoint), and the mean Clinical Global Impression-Improvement score. Aripiprazole was generally well tolerated in this patient population in the two 8-week studies and a 52-week study, with most adverse events being mild to moderate in severity. Aripiprazole was associated with weight gain in both the short- and long-term studies; data from the long-term study indicated that the increase in bodyweight reached a plateau at 3-6 months.

Retrospective review of clozapine in the treatment of patients with autism spectrum disorder and severe disruptive behaviors

Autism spectrum disorder (ASD) is a serious childhood-onset disorder in which social and language development are primarily affected, with associated repetitive behavior and, in some patients, behavioral symptoms including aggression and self-injury. In ASD, risperidone and aripiprazole are the only second-generation antipsychotic drugs that have shown to decrease disruptive behaviors in large-scale, controlled, double-blind studies. However, in some patients, these medications are not effective. Clozapine, a second-generation antipsychotic drug known to be effective in the treatment of aggression associated with schizophrenia, has received little attention in ASD.We conducted a retrospective analysis of the changes in disruptive behaviors for all patients with ASD treated with clozapine from 2002 to 2010. Disruptive behaviors were monitored during the 4 to 6 months before and after the initiation of clozapine. Long-term tolerance (10 months to 7 years) was also assessed. The relationship between disruptive behaviors and period of treatment (before and after clozapine) was studied with a generalized linear marginal model. Clozapine resulted in a significant 2-fold decrease in the number of the days with aggression, a decrease in the number of psychotropic drugs, and a decrease in the dose of the antipsychotic drugs. The long-term tolerance of clozapine (white blood cell count and extrapyramidal effects) was good, with the exception of significant weight gain (14.3 ± 10.9 kg), the occurrence of metabolic syndrome in 1 patient, and tachycardia in another patient.These results suggest that clozapine should be considered for the management of disruptive behaviors in patients with ASD not improved by first-line antipsychotic drugs.

A systematic review of medical treatments for children with autism spectrum disorders

CONTEXT

As many as 1 in every 110 children in the United States has an autism spectrum disorder (ASD). Many medical treatments for ASDs have been proposed and studied, but there is currently no consensus regarding which interventions are most effective.

OBJECTIVE

To systematically review evidence regarding medical treatments for children aged 12 years and younger with ASDs.

METHODS

We searched the Medline, PsycInfo, and ERIC (Education Resources Information Center) databases from 2000 to May 2010, regulatory data for approved medications, and reference lists of included articles. Two reviewers independently assessed each study against predetermined inclusion/exclusion criteria. Studies of secretin were not included in this review. Two reviewers independently extracted data regarding participant and intervention characteristics, assessment techniques, and outcomes and assigned overall quality and strength-of-evidence ratings on the basis of predetermined criteria.

RESULTS

Evidence supports the benefit of risperidone and aripiprazole for challenging and repetitive behaviors in children with ASDs. Evidence also supports significant adverse effects of these medications. Insufficient strength of evidence is present to evaluate the benefits or adverse effects for any other medical treatments for ASDs, including serotonin-reuptake inhibitors and stimulant medications.

CONCLUSIONS

Although many children with ASDs are currently treated with medical interventions, strikingly little evidence exists to support benefit for most treatments. Risperidone and aripiprazole have shown benefit for challenging and repetitive behaviors, but associated adverse effects limit their use to patients with severe impairment or risk of injury.

Managing irritability and aggression in autism spectrum disorders in children and adolescents

Children with autism and autism spectrum disorders have a high rate of irritability and aggressive symptoms. In one study up to 20% of children with autism have symptoms of irritability and aggression including aggression, severe tantrums, and deliberate self injurious behavior (Lecavalier [2006] J. Autism Dev. Disord. 36:1101-1114.). These symptoms can lead to impairment and distress in both home and school settings. Medications to treat the irritability will be discussed across categories of antipsychotics, antidepressants, antihypertensive agents, and others. Emphasis will be placed on medications with the most safety and efficacy and FDA approval.

Long-Term Aripiprazole in Youth With Developmental Disabilities Including Autism

We retrospectively reviewed clinic charts of 21 children and adolescents with developmental disabilities including autism spectrum disorders (ASD) treated consecutively with aripiprazole (ARI) for irritability and severe challenging behaviors. Data extracted include age, sex, and race; level of intellectual disability (ID); Diagnostic and Statistical Manual-IV diagnoses including comorbidity, ARI dosage, and treatment duration; other psychoactive medications and Clinical Global Impressions-Improvement (CGI-I) at baseline and end point; weight; height; and side effects. Body mass index (BMI) z scores are compared with Centers for Disease Control norms. Eleven boys and 10 girls with ID and/or ASD ages 8 to 18 years (mean age 13.4 years) received ARI; mean dose was 8.4 mg/day (range 2.5 to 15); average duration was 60.6 weeks (7 to 132). Eleven of 21 patients (52%) met CGI-I response of ≤ 2. ARI was well tolerated, including together with stimulants, divalproex, or less commonly other medications. Mean BMI was 23.8 ± 5.9 at baseline and 24.2 ± 5.2 at end. Mean BMI z score increase was 0.06 ± 0.67. Four individuals (19%) manifested early intolerable weight gain. In this long-term clinical sample, ARI was effective in 52% and well tolerated. ARI was mostly weight neutral; early weight gain was intolerable in 19%. Larger long-term outcome studies are warranted in this population.

Aripiprazole for the treatment of irritability associated with autism

INTRODUCTION

Irritability (including tantrums, aggression and moodiness) is often associated with autistic disorder. Children with autism are frequently prescribed atypical antipsychotic medications for these behaviors. Although multiple agents have been found to be effective, the safety and tolerability of each antipsychotic may be the determining factor in its selection.

AREAS COVERED

The pharmacokinetics, pharmacodynamics, safety and efficacy data on aripiprazole for the treatment of irritability associated with autism are discussed. Knowledge of the mechanism of action, advantages and disadvantages relative to other atypical antipsychotics, and an appreciation of the efficacy of aripiprazole when used to treat irritability in autism is also explored in this paper.

EXPERT OPINION

Aripiprazole may have a more favorable side-effect profile than another commonly prescribed medication, risperidone, because of its unique mechanism of action. It seems to be effective in treating irritability associated with autism, but more research is needed.

Metabolic and endocrine adverse effects of second-generation antipsychotics in children and adolescents: A systematic review of randomized, placebo controlled trials and guidelines for clinical practice

Second-generation antipsychotics (SGA) are being used more often than ever before in children and adolescents with psychotic and a wide range of non-psychotic disorders. Several SGA have received regulatory approval for some paediatric indications in various countries, but off-label use is still frequent. The aim of this paper was to perform a systematic review and critically evaluate the literature on cardiometabolic and endocrine side-effects of SGA in children and adolescents through a Medline/Pubmed/Google Scholar search of randomized, placebo controlled trials of antipsychotics in children and adolescents (<18 years old) until February 2010. In total, 31 randomized, controlled studies including 3595 paediatric patients were identified. A review of these data confirmed that SGA are associated with relevant cardiometabolic and endocrine side-effects, and that children and adolescents have a high liability to experience antipsychotic induced hyperprolactinaemia, weight gain and associated metabolic disturbances. Only weight change data were sufficiently reported to conduct a formal meta-analysis. In 24 trials of 3048 paediatric patients with varying ages and diagnoses, ziprasidone was associated with the lowest weight gain (-0.04kg, 95% confidence interval [CI]: -0.38 to +0.30), followed by aripiprazole (0.79kg, 95% CI: 0.54 to 1.04], quetiapine (1.43kg, 95% CI: 1.17 to 1.69) and risperidone (1.76kg, 95% CI: 1.27 to 2.25) were intermediate, and olanzapine was associated with weight gain the most (3.45kg, 95% CI: 2.93 to 3.97). Significant weight gain appeared to be more prevalent in patients with autistic disorder who were also younger and likely less exposed to antipsychotics previously. These data clearly suggest that close screening and monitoring of metabolic side effects is warranted and that the least cardiometabolically problematic agents should be used first whenever possible. A good collaboration between child- and adolescent psychiatrists, general practitioners and paediatricians is essential to maximize overall outcomes and to reduce the likelihood of premature cardiovascular morbidity and mortality.

Psychopharmacology of autistic spectrum disorders in children and adolescents

This article provides an overview of the psychopharmacologic management of irritability, hyperactivity, and repetitive behaviors in children and adolescents with autism spectrum disorder. A review of the current literature on medications used to treat these conditions with emphasis on randomized controlled trials is presented.

Psychopharmacology in autism: an update

Autism spectrum disorders are characterized by impairment in social reciprocity, disturbances in language and communication, restricted interests and repetitive behaviors of various types, as defined by the DSM-IV. The neurobiological bases of these disorders are poorly understood, although several abnormalities have been found. Pharmacotherapy in autism spectrum disorders lacks a solid, reliable neurobiological basis and at present it is mainly directed at the so-called associated behavioral symptoms, with limited relevance to core symptoms. Atypical neuroleptics, especially risperidone, have been shown to be useful in the treatment of behavioral symptoms in autism. Recent trials with SSRIs did not show remarkable results, in spite of their promising potential role. Attention deficit and hyperactivity disorder medications may be useful for counteracting the additional features of hyperactivity and short attention span. Antiepileptics have shown promising results but there are no specific indications for them as of yet. Research is now directed at evaluating novel treatments and combined behavioral and pharmacologic treatments, since behavioral interventions are the mainstay of the early treatment of autism. An update of currently available pharmacological treatments is provided.

Psychopharmacological treatment of ADHD symptoms in children with autism spectrum disorder

One of the most frequently reported behavioral concerns among children with autism spectrum disorder (ASD) is high rates of activity and inattention, symptoms that are often associated with attention deficit hyperactivity disorder (ADHD). Although there is a considerable body of research regarding the appropriate treatment of ADHD symptoms among typically developing children, the research among children with ASD is more limited. The evidence to date suggests that medication response rates among children with ASD are considerably lower than among typically developing children and that children with ASD tend to be at greater risk for experiencing side effects. The purpose of the present paper is to review the available research on the treatment of ADHD symptoms in children with ASD. This paper summarizes the data on a range of pharmacological options and provides specific recommendations for how best to clinically manage these symptoms.

Pharmacotherapeutics of Tourette syndrome and stereotypies in autism

Tourette syndrome (TS) and stereotypy in autism spectrum disorders (ASDs) are 2 common movement disorders in childhood. The objective of this review was to summarize randomized controlled trials published over the past 5 years as an update of the current pharmacotherapeutic options for the treatment of tics, TS, and motor stereotypies in children with ASD. We searched MEDLINE (2005-May 2010) for randomized controlled trials of medications used for the treatment of these disorders. For the treatment of tics in TS, 2 trials suggest that levetiracetam is not effective, whereas 1 trial found that topiramate was effective. Single clinical trials of metoclopramide, atomoxetine, and ondansetron were of limited quality, preventing conclusions to be made regarding the usefulness of these treatments for tic disorders. For the treatment of stereotypy in children with ASD, risperidone has been shown in both a Cochrane review in 2006 and 2 subsequent randomized control trials to be effective. The addition of pentoxifylline to risperidone may have added benefit. Haloperidol did not improve stereotypy and was poorly tolerated. There is good evidence that aripiprazole is effective in the treatment of sterotypies in children with ASD. A large randomized trial of citalopram did not show any improvement in stereotypy. Single trials of levetiracetam, guanfacine, and atomoxetine suggest they are not useful in the reduction of stereotypy in children with ASD.

Line-item analysis of the Aberrant Behavior Checklist: results from two studies of aripiprazole in the treatment of irritability associated with autistic disorder

OBJECTIVES

The aim of this study was to evaluate the efficacy of aripiprazole in the treatment of discrete symptoms of irritability associated with autistic disorder, as well as other symptoms captured on the Aberrant Behavior Checklist (ABC).

METHODS

This was a post hoc analysis of data from two 8-week, randomized, double-blind, multicenter trials to evaluate the efficacy of aripiprazole dosed flexibly (2-15 mg/day, n=47) or fixed (5, 10, or 15 mg/day, n = 166) versus placebo (flexibly dosed, n = 51; fixed dose, n = 52). The effects of treatment on the 58 ABC items were evaluated.

RESULTS

Statistically significantly greater improvement was seen with aripiprazole versus placebo (p < 0.05) for all arms in both trials on the ABC-Irritability total subscale score and on the following individual ABC-Irritability items: Mood changes quickly, cries/screams inappropriately, and stamps feet/bangs objects. Several additional items measuring tantrum-like behaviors improved in the flexibly dosed trial and at least one arm of the fixed-dose trial (p < 0.05). Measures of self-injurious behavior, which had low baseline values, demonstrated numerical, but not statistically significant, improvement in both trials. Statistically significantly greater improvement in ABC Stereotypic Behavior and Hyperactivity total subscale scores was also consistent across all arms in both trials. In particular, there was a cluster of items related to hyperkinesis that were consistently sensitive to treatment.

CONCLUSIONS

Aripiprazole is efficacious in the treatment of irritability in children and adolescents with autistic disorder, particularly with respect to symptoms associated with tantrum behavior.

Emerging role of aripiprazole for treatment of irritability associated with autistic disorder in children and adolescents

Autistic disorder is a largely misunderstood and difficult to treat neurodevelopmental disorder. Three core domains of functioning are affected by autistic disorder, ie, socialization, communication, and behavior. Signs of autistic disorder may be present early, but are frequently overlooked, resulting in a delay in its diagnosis and a subsequent delay in treatment. No one definitive therapy is available, and treatment consists of early educational and behavioral interventions, as well as drug therapy. Atypical antipsychotics have often been used in the treatment of autistic disorder to target irritability, aggression, and self-injurious behavior, all of which can interfere with other aspects of treatment. One atypical antipsychotic, aripiprazole, has recently been approved for treatment of irritability associated with autistic disorder. Based on the results from two randomized, controlled trials, with efficacy data from nearly 300 patients, treatment with aripiprazole was associated with reductions in irritability, global improvements in behavior, and improvements in quality of life from both the patient and caregiver perspectives. Dosage of aripiprazole ranged from 5 mg to 15 mg per day. Aripiprazole was well tolerated during clinical trials, with most adverse events considered mild or moderate. Clinically relevant weight gain occurred in about 30% of patients given aripiprazole, although when compared with other atypical antipsychotics, aripiprazole appears to have fewer metabolic effects and a lower risk of weight gain. However, pediatric patients taking any atypical antipsychotic should be carefully monitored for potential adverse events, because the long-term effects of antipsychotic therapy in this population are not well known. When used appropriately, aripiprazole has the potential to be an effective treatment for children with autistic disorder to improve irritability and aggressive behavior and improve quality of life.

Self-injurious behaviour in people with intellectual disability

PURPOSE OF REVIEW

To provide a critical evaluation of a broad range of peer-reviewed published studies of relevance to self-injurious behaviour in people with intellectual disability and autism spectrum disorders.

RECENT FINDINGS

The review covers the prevalence of self-injurious behaviour, the characteristics of those showing the behaviour, self-injury in autism spectrum disorders, biological influences on self-injurious behaviour, behavioural assessment and psychological and pharmacological interventions.

SUMMARY

The recent literature describes systematic evaluation of the efficacy of aripiprazole, and parent training combined with risperidone. Meta-analyses of behavioural interventions provide evidence of their efficacy and related research describes beneficial modification to behavioural assessment procedures. The prevalence literature provides data on individual characteristics that are associated with persistence and presence of self-injury and that might be considered as risk markers. Pain behaviour appears to be associated with self-injury, with implications for theories of the involvement of endorphins, and as a causal factor. In combination, these research findings demonstrate the multiple influences on self-injurious behaviour that must be taken into account in the assessment, formulation, intervention process.

Emerging drugs for the treatment of symptoms associated with autism spectrum disorders

IMPORTANCE OF THE FIELD

Autism spectrum disorders, or pervasive developmental disorders (PDDs), are neurodevelopmental disorders defined by qualitative impairment in social interaction, impaired communication and stereotyped patterns of behavior. The most common forms of PDD are autistic disorder (autism), Asperger's disorder and PDD not otherwise specified. Recent surveillance studies reveal an increase in the prevalence of autism and related PDDs. The use of pharmacologic agents in the treatment of these disorders can reduce the impact of interfering symptoms, providing relief for affected individuals and their families.

AREAS COVERED IN THIS REVIEW

This review examines results from neurobiologic research in an attempt to both elucidate the pathophysiology of autism and guide the development of pharmacologic agents for the treatment of associated symptoms. The safety and efficacy data of drugs currently in clinical use for the treatment of these symptoms, as well as pharmaceuticals currently under development, are discussed.

WHAT THE READER WILL GAIN

This comprehensive review will deepen the reader's current understanding of the research guiding the pharmacologic treatment of symptoms associated with autism and related PDDs. Areas of focus for future research are also discussed. The need for large-scale investigation of some commonly used pharmacologic agents, in addition to the development of drugs with improved efficacy and safety profiles, is made evident.

TAKE HOME MESSAGE

Despite progress in the development of pharmacologic treatments for a number of interfering symptom domains associated with autism and other PDDs, a great deal of work remains.

Emerging pharmacotherapies for neurodevelopmental disorders

A growing and interdisciplinary translational neuroscience research effort for neurodevelopmental disorders (NDDs) is investigating the mechanisms of dysfunction and testing effective treatment strategies in animal models and, when possible, in the clinic. NDDs with a genetic basis have received particular attention. Transgenic animals that mimic genetic insults responsible for disease in man have provided insight about mechanisms of dysfunction, and, surprisingly, have shown that cognitive deficits can be addressed in adult animals. This review will present recent translational research based on animal models of genetic NDDs, as well as pharmacotherapeutic strategies under development to address deficits of brain function for Down syndrome, fragile X syndrome, Rett syndrome, neurofibromatosis-1, tuberous sclerosis, and autism. Although these disorders vary in underlying causes and clinical presentation, common pathways and mechanisms for dysfunction have been observed. These include abnormal gene dosage, imbalance among neurotransmitter systems, and deficits in the development, maintenance and plasticity of neuronal circuits. NDDs affect multiple brain systems and behaviors that may be amenable to drug therapies that target distinct deficits. A primary goal of translational research is to replace symptomatic and supportive drug therapies with pharmacotherapies based on a principled understanding of the causes of dysfunction. Based on this principle, several recently developed therapeutic strategies offer clear promise for clinical development in man.

Aripiprazole for irritability associated with autistic disorder in children and adolescents aged 6–17 years

Aripiprazole was recently US FDA-approved to treat irritability in children and adolescents with autistic disorder aged 6–17 years. There are currently only two psychotropics approved by the FDA to treat irritability in the autistic population. This drug profile will discuss available studies of aripiprazole in individuals with pervasive developmental disorders, two of which led to its recent FDA approval. We will discuss the efficacy, as well as the safety and tolerability of the drug documented in these studies. In addition, the chemistry, pharmacokinetics, metabolism and mechanism of action of aripiprazole will be reviewed.

Improving the prediction of response to therapy in autism

Autism is a heterogeneous disorder involving complex mechanisms and systems occurring at diverse times. Because an individual child with autism may have only a subset of all possible abnormalities at a specific time, it may be challenging to identify beneficial effects of an intervention in double-blind, randomized, controlled trials, which compare the mean responses to treatments. Beneficial effects in a small subset of children may be obscured by the lack of effect in the majority. We review the evidence for several potential model systems of biochemical abnormalities that may contribute to the etiology of autism, we describe potential biomarkers or treatment targets for each of these abnormalities, and we provide illustrative treatment trials using this methodology. Potential model systems include immune over and under reactivity, inflammation, oxidative stress, free fatty acid metabolism, mitochondrial dysfunction, and excitotoxicity. Including potential biomarkers and targeted treatments in clinical trials for autism provides a potential method for limiting the heterogeneity of enrolled subjects, which may improve the power of studies to identify beneficial effects of treatments while also improving the understanding of the disease.

Aripiprazole in autism spectrum disorders and fragile X syndrome

Autism spectrum disorders (ASDs) are childhood onset developmental disorders characterized by impairment of social skills and repetitive behavior, and also for classic autistic disorder, a significant impairment of communication. In addition to these core symptom domains, persons with ASDs frequently exhibit interfering behavioral symptoms, including irritability marked by aggression, self-injurious behavior, and severe tantrums. Aripiprazole is an atypical or newer generation antipsychotic with a unique mechanism of action impacting dopaminergic and serotonergic neurotransmission. The drug has been found efficacious for several indications, including most recently for use targeting irritability associated with autistic disorder in youth. Fragile X syndrome is the most common inherited cause of developmental disability and the most common known single gene cause of ASDs. As in idiopathic ASDs, irritable behavior is often exhibited by persons with fragile X syndrome. However, research to date in this disorder has not focused on this target symptom cluster. An initial pilot study has begun to assess the impact of aripiprazole on irritability in youth with fragile X syndrome.

Effects of repeated and acute aripiprazole or haloperidol treatment on dopamine synthesis in the dorsal striatum of young rats: comparison to adult rats

The purpose of the present study was to determine whether repeated treatment with the D2 partial agonist aripiprazole or the D2 antagonist haloperidol alters dopamine (DA) synthesis characteristics in the dorsal striatum of young rats. To this end, rats received a daily pretreatment regimen of aripiprazole or haloperidol on postnatal days (PD) 10-20 and were tested 24 or 72 h later after an acute injection of vehicle, aripiprazole, haloperidol, or quinpirole (a D2 agonist). For comparison purposes, adult rats were pretreated with an 11-day regimen of saline or haloperidol on PD 70-80 and DA synthesis was measured after acute drug treatment on PD 83. Dorsal striatal DA synthesis was determined by measuring L-dihydroxyphenylalanine accumulation after NSD-1015 treatment. In a separate experiment, the ability of repeated drug treatment to up-regulate dorsal striatal D2 receptors was assessed in young and adult rats 72 h after drug discontinuation. The major findings of this study were that: (a) acute treatment with haloperidol and aripiprazole increased DA synthesis while quinpirole reduced it; (b) pretreatment with haloperidol and aripiprazole blunted the synthesis-modulating effects of acutely administered dopaminergic drugs; and (c) DA synthesis of young and adult rats was affected in a qualitatively similar manner by DA agonist, antagonist, and partial agonist drugs. In conclusion, results from the present study suggest that synthesis-modulating autoreceptors in the dorsal striatum are functionally mature by the end of the preweanling period and DA synthesis declines to near basal levels during the course of repeated aripiprazole treatment.