Loxapine treatment in an autistic child with aggressive behavior: therapeutic challenges

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.

Missing from the Narrative: A Seven-Decade Scoping Review of the Inclusion of Black Autistic Women and Girls in Autism Research

The intersectional experiences of Black autistic women and girls (BAWG) are missing from medical and educational research on autism spectrum disorder (ASD). Understanding the intersectional experiences of BAWG is important due to the rising prevalence of autism in Black children and girls (Centers for Disease Control and Prevention (CDC), 2020) and the concurrent lack of availability of culturally relevant autism-related interventions (Maenner et al., 2020; West et al., 2016). Intersectionality is the study of the overlapping discrimination produced by systems of oppression (Collins, 2019; Crenshaw, 1989, 1991) and allows the researcher to simultaneously address race and disability in special education (Artiles, 2013). In this scoping review, the authors used the PRISMA-ScR checklist (Tricco et al., 2018) and Arskey and O'Malley's (2005) framework to investigate the degree to which autism-related research (ARR) has included the intersectional experiences of BAWG. Utilizing narrative synthesis, strengths and gaps across the current body of literature are identified in order to set new directions for intersectional ARR. Overall, the authors found that across a 77-year period, three studies foregrounded BAWG and none addressed intersectionality as measured through criteria advanced by García and Ortiz (2013). These results reveal the scholarly neglect BAWG face in ARR, discourse, policy, and practice. A future agenda including research, practice, and policy priorities is identified and discussed.

Autism presentation in female and Black populations: Examining the roles of identity, theory, and systemic inequalities

LAY ABSTRACT

Although the prevalence of autism has been rising in recent years, disparities in diagnosis still remain. Female and Black populations in the United States are diagnosed later, are more likely to have an intellectual disability, and are excluded from research as well as services designed for autistic individuals. Autistic Black girls are effectively invisible in the current scientific literature. Intersectional theory, which looks at a person as a whole, examines models that are inclusive toward diverse gender, ability, and racial/ethnic backgrounds. This theory may be a useful approach to clinical and research work with autism so that practitioners may be most effective for the whole population of autistic people. The authors recommend research focusing on inclusion of autistic populations with intellectual disability and research studies that include evaluations as part of the procedure. Clinically, the authors recommend a focus on screening all young children for autism and improving provider knowledge in working with diverse autistic populations.

Clinical Trial Simulations and Pharmacometric Analysis in Pediatrics: Application to Inhaled Loxapine in Children and Adolescents

BACKGROUND AND OBJECTIVES

Loxapine for inhalation is a drug-device combination product approved in adults for the acute treatment of agitation associated with schizophrenia or bipolar I disorder. The primary objective of this study was to develop a clinical trial protocol to support a phase I pharmacokinetic study in children aged 10 years and older. In addition, this report details the results of the clinical study in relation to the predicted likelihood of achieving the target exposure associated with therapeutic effect in adults.

METHODS

A nonlinear mixed-effects population pharmacokinetic model was developed using adult data and was adjusted for the targeted pediatric age groups by applying allometric scaling to account for body size effects. Based on this pediatric model, age-appropriate regimens to achieve loxapine exposures similar to the ones associated with therapeutic effect in the adult studies were identified via trial simulation. D-optimal design and power analysis were conducted to identify optimal pharmacokinetic sampling times and sample size, respectively.

RESULTS

The developed clinical trial design formed the basis of a phase I study to assess the safety and pharmacokinetics of loxapine for inhalation in children aged 10 years and older (ClinicalTrials.gov ID: NCT02184767).

CONCLUSION

The results of the study indicated that overall loxapine exposures were consistent with what had been predicted by the trial simulations. The presented approach illustrates how modeling and simulation can assist in the design of informative clinical trials to identify safe and effective doses and dose ranges in children and adolescents.

Loxapine for Reversal of Antipsychotic-Induced Metabolic Disturbances: A Chart Review

Loxapine substitution is a promising option for patients with autism spectrum disorder (ASD) who develop antipsychotic-induced metabolic illness. We performed a chart review of 15 adolescents and adults meeting DSM-IV-TR criteria for ASD, all with antipsychotic-associated weight gain, who received low dose loxapine in an attempt to taper or discontinue the weight gain-associated antipsychotic. Mean weight loss was -5.7 kg, mean BMI reduction was -1.9, and mean triglyceride reduction was -33.7 mg/dl. At chart review, 14 of 15 subjects were rated 2 (Much Improved) or 1 (Very Much Improved) on the Clinical Global Impressions-Improvement scale (CGI-I). Low dose loxapine addition in most cases enabled taper of offending antipsychotics, significantly reversed drug-induced metabolic disturbances and improved irritability.

Low Dose Loxapine: Neuromotor Side Effects and Tolerability in Autism Spectrum Disorders

OBJECTIVE

New and repurposed drugs are urgently needed to treat individuals with autism spectrum disorders (ASD). Loxapine (LOX) in low doses of 5-15 mg/day resembles an atypical antipsychotic (Stahl 2002 ). Our recent open pilot study of LOX found significant behavioral improvements and overall weight neutrality in 16 adolescents and adults with ASD. The present study examined an outpatient sample for LOX neuromotor tolerability.

METHODS

Consecutive outpatients with Diagnostic and Statistical Manual of Mental Disorders, 4th ed, Text Revision (DSM-IV-TR) ASD diagnoses receiving LOX were examined for tardive dyskinesia (TD) and extrapyramidal side effects (EPS) using the Dyskinesia Identification System: Condensed User Scale (DISCUS), and for akathisia using the Barnes Akathisia Rating Scale. Data were also then retrospectively extracted from clinic charts regarding age, gender, diagnoses, LOX doses, treatment duration, concomitant medications, and LOX dosage reductions.

RESULTS

Thirty-four subjects (25 male, 9 female) participated. Mean age was 23.4 years at LOX initiation (range 8-52). Thirteen subjects (38.2%) received loxapine for ≥5 years. Mean LOX dose was 8.9 mg/day (range 5-30 mg) and mean duration was 4.2 years (range 0.8-13). Fourteen subjects (41.2%) received concomitant atypical antipsychotics. Benztropine was prescribed in 5 of 34 subjects (14.7%). Three subjects manifested tics at baseline, but lower final DISCUS scores. Subject 26, with Prader-Willi syndrome, manifested TD. Apart from LOX 5 mg daily he received paroxetine 40 mg daily, which reduces LOX metabolism significantly. Akathisia objective scores were positive in 6 subjects (17.6%): Subject 2 scored 3 (pacing was present also at baseline); subjects 6, 7, and 11 each scored 1; and subjects 18 and 23 each scored 2. Six of 9 subjects (66.7%) with expressive language were positive for subjective akathisia.

CONCLUSIONS

Low dose LOX was well tolerated, with lower than expected TD rates. This confirms clinical resemblance to an atypical antipsychotic. Individuals with neuromuscular problems including Prader-Willi Syndrome receiving LOX require close monitoring. Further study of LOX in ASD is warranted.

Loxapine add-on for adolescents and adults with autism spectrum disorders and irritability

OBJECTIVES

Our clinical experience with low dose loxapine (5-15 mg/day) suggests promising efficacy and safety for irritability in autism spectrum disorders (ASD). We studied low dose loxapine prospectively in adolescents and adults with ASD and irritability. Additionally, we measured loxapine and metabolite concentrations, and brain-derived neurotrophic factor (BDNF) as a biomarker of neuromodulation.

METHODS

We performed a 12 week open trial of add-on loxapine in subjects, ages 13-65 years, diagnosed with ASD, and Aberrant Behavior Checklist-Irritability (ABC-I) subscale scores >14. Loxapine was dosed flexibly up to 15 mg daily, starting with 5 mg on alternate days. From weeks 1 to 6, other psychoactive medications were tapered if possible; from weeks 6 to 12, all medication doses were held stable. The primary outcome was the Clinical Global Impressions-Improvement subscale (CGI-I), ratings of Much Improved or Very Much Improved. Secondary outcomes were the ABC-I, Repetitive Behavior Scale-Revised, and Schalock Quality of Life scale. Serum BDNF and loxapine and metabolite concentrations were assayed. BDNF rs6265 was genotyped.

RESULTS

Sixteen subjects were enrolled; 12 completed all visits. Median age was 18 years (range 13-39). Median final loxapine dose was 7.5 mg/day (2.5-15). All 14 subjects (100%) with data at week 12 were rated as Much Improved on CGI-I at 12 weeks. Mean change on ABC-I at 12 weeks was -31%, p=0.01. Mean body mass index (BMI)-Z decreased between weeks 6 and 12, p=0.03. Side effects were minimal, and prolactin elevation occurred in only one subject. BDNF concentrations measured in 11 subjects increased significantly (p=0.04). Subjects with AG genotype for BDNF rs6265 required a lower dose of loxapine at study end, but had similar behavioral and BDNF concentration changes as the GG genotype.

CONCLUSIONS

Low dose loxapine shows promise as a repurposed drug for irritability in ASD. Loxapine effects on BDNF warrant further study.

Revisiting loxapine: a systematic review

Loxapine is an antipsychotic used in psychiatry for over 40 years with a well-established profile. Loxapine is a dibenzoxazepine tricyclic antipsychotic agent, available for oral, intramuscular and inhalatory administration. In the light of the recent approval by the regulatory agencies of inhaled loxapine for use in the acute treatment of mild-to-moderate agitation in adults affected with schizophrenia or bipolar disorder, this article aims to critically review the available literature on loxapine, irrespective of its formulation. This review examines the efficacy and tolerability of the various formulations of loxapine in the treatment of agitation and aggression in patients affected with schizophrenia, bipolar disorder and other psychiatric conditions. A comprehensive and systematic literature search of PubMed/MEDLINE was conducted, and relevant pharmacodynamic and pharmacokinetic data was included. The findings from the literature were critically reviewed and synthesized. The available data suggests that the antipsychotic efficacy of loxapine is similar to the efficacy of other typical or atypical antipsychotics, with an adverse effects profile comparable to that of the typical antipsychotics at high doses for chronic treatment. As an acute treatment in agitation associated with schizophrenia or bipolar disorder, inhaled loxapine was developed as an innovative and rapid option which appears to be efficacious and tolerable.

The psychopharmacology of aggressive behavior: a translational approach: part 2: clinical studies using atypical antipsychotics, anticonvulsants, and lithium

Patients experiencing mental disorders are at an elevated risk for developing aggressive behavior. In the past 10 years, the psychopharmacological treatment of aggression has changed dramatically owing to the introduction of atypical antipsychotics on the market and the increased use of anticonvulsants and lithium in the treatment of aggressive patients.This review (second of 2 parts) uses a translational medicine approach to examine the neurobiology of aggression, discussing the major neurotransmitter systems implicated in its pathogenesis (serotonin, glutamate, norepinephrine, dopamine, and γ-aminobutyric acid) and the neuropharmacological rationale for using atypical antipsychotics, anticonvulsants, and lithium in the therapeutics of aggressive behavior. A critical review of all clinical trials using atypical antipsychotics (aripiprazole, clozapine, loxapine, olanzapine, quetiapine, risperidone, ziprasidone, and amisulpride), anticonvulsants (topiramate, valproate, lamotrigine, and gabapentin), and lithium are presented. Given the complex, multifaceted nature of aggression, a multifunctional combined therapy, targeting different receptors, seems to be the best strategy for treating aggressive behavior. This therapeutic strategy is supported by translational studies and a few human studies, even if additional randomized, double-blind, clinical trials are needed to confirm the clinical efficacy of this framework.