Model-based comparison of subcutaneous versus sublingual apomorphine administration in the treatment of motor fluctuations in Parkinson's disease.

The objective of this study was to compare the effectiveness of subcutaneous (SC) and sublingual (SL) formulations of apomorphine for the treatment of motor fluctuations in Parkinson's disease using a pharmacokinetics (PK)/pharmacodynamics (PD) modeling approach. The PK of SC and SL apomorphine are best described by a one-compartment model with first-order absorption and a two-compartment model with delayed absorption, respectively. The PK/PD model relating apomorphine plasma concentrations to the Unified Parkinson's Disease Rating Scale (UPDRS) motor scores was described by a sigmoidal Emax model assuming effective concentration = drug concentration in an effect compartment. Apomorphine concentrations and UPDRS motor scores were simulated from the PK/PD models using 500 hypothetical subjects. UPDRS motor score change from baseline was evaluated using time to clinically relevant response, response duration, area under the curve, maximal response, and time to maximal response. Higher doses of each apomorphine formulation were associated with shorter time to response, longer response duration, and greater maximal response. Although the mean maximal responses to SC and SL apomorphine were comparable, the time to response was four times shorter (7 vs. 31 min) and time to maximal response was two times shorter (27 vs. 61 min) for 4 mg SC vs. 50 mg SL. Thus, faster onset of action was observed for the SC formulation compared to SL. These data may be useful for physicians when selecting "on demand" therapy for patients with Parkinson's disease experiencing motor fluctuations.

Closing the gap: unmet needs of individuals with impulsive aggressive behavior observed in children and adolescents.

Impulsive aggressive (IA, or impulsive aggression) behavior describes an aggregate set of maladaptive, aggressive behaviors occurring across multiple neuropsychiatric disorders. IA is reactive, eruptive, sudden, and unplanned; it provides information about the severity, but not the nature, of its associated primary disorder. IA in children and adolescents is of serious clinical concern for patients, families, and physicians, given the detrimental impact pediatric IA can have on development. Currently, the ability to properly identify, monitor, and treat IA behavior across clinical populations is hindered by two major roadblocks: (1) the lack of an assessment tool designed for and sensitive to the set of behaviors comprising IA, and (2) the absence of a treatment indicated for IA symptomatology. In this review, we discuss the clinical gaps in the approach to monitoring and treating IA behavior, and highlight emerging solutions that may improve clinical outcomes in patients with IA.

A Double-Blind, Randomized Study of Extended-Release Molindone for Impulsive Aggression in ADHD.

Objective: To evaluate efficacy and safety of SPN-810 (extended-release molindone) in a Phase-2b, randomized, double-blind, placebo-controlled, dose-ranging study of children (6-12 years) with ADHD and persistent impulsive aggression (IA). Method: After lead-in, children were randomized to (a) placebo (N = 31); (b) low-dose (N = 29, 12/18 mg/day); (c) medium-dose (N = 30, 24/36 mg/day); and (4) high-dose (N = 31, 36/54 mg/day) groups. Treatment included ~2.5-week titration, 3-week maintenance, and 1-week tapering/conversion, alongside existing monotherapy (stimulants/nonstimulants) and behavioral therapy. The primary endpoint was change in Retrospective-Modified Overt Aggression Scale (R-MOAS) score at end of study, with safety monitored. Results: A total of 95 (78.5%) children completed the study. Aggression (R-MOAS) improved with low and medium doses (low dose: p = .031; medium dose: p = .024; high dose: p = .740). The most common adverse events were headache (10.0%), sedation (8.9%), and increased appetite (7.8%). Conclusion: These results suggest SPN-810 may be effective in reducing residual IA behaviors in children with ADHD. Research is still needed to support the benefit-risk profile of SPN-810 in pediatric populations.

A Novel Assessment Tool for Impulsive Aggression in Children with Attention-Deficit/Hyperactivity Disorder.

Objective: To establish the validity and reliability of a provisional 30-item impulsive aggression (IA) diary in children (ages 6-12 years, inclusive) with attention-deficit/hyperactivity disorder (ADHD). Methods: The provisional 30-item IA diary was administered for 14 days to parents of children with ADHD and IA symptoms (n = 103). Key inclusion criteria: confirmed ADHD diagnosis; signs of IA as measured by a Retrospective-Modified Overt Aggression Scale (R-MOAS) score ≥20 and an Aggression Questionnaire score of -2 to -5. Analyses included inter-item correlations, exploratory factor analysis (EFA), item response theory (IRT) modeling, internal consistency, test-retest reliability (TRT), concurrent validity (estimated by correlation between the IA diary and the R-MOAS/Nisonger Child Behavior Rating Form), and known-groups methods. Results: The prevalence rates of 15 (50.0%) items were found to be too low (<1%) for analysis; three items with prevalence rates ≤1% were retained, as content validity was deemed high by clinical experts. The remaining 12 behavior items had prevalence rates of 2.7%-73.6%. EFA and IRT models confirmed two subdomains in the IA diary included within a general domain of IA behavior frequency, yielding a single total behavioral frequency score (TBFS). Internal consistency was high for this TBFS (marginal reliability = 0.86 and α = 0.73). TRT for the TBFS, based on the intraclass correlation coefficient, was 0.8. Concurrent validity of TBFS with R-MOAS ranged from r = 0.49 to r = 0.62. Conclusion: The final 15-item IA diary is a reliable, psychometrically validated IA measurement tool that will allow clinicians and researchers to assess the frequency of IA behavior.

Application of the Impulsive Aggression Diary in Adolescents with Attention-Deficit/Hyperactivity Disorder.

Objective: Impulsive aggression (IA) is a maladaptive form of aggressive behavior that is an associated feature of neuropsychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD). As one of the most common forms of aggressive behavior, IA is a serious clinical concern. Recognition, monitoring, and management of IA symptoms are complicated by the lack of IA-specific psychometric instruments and evidence-based treatments. A recently developed electronic observer-reported outcome instrument has been validated in children for monitoring the frequency of 15 IA-related behaviors in the context of ADHD. This study seeks to first determine if the behaviors included in the pediatric IA diary are applicable to adolescents with ADHD, and second, compare the reliability of adolescent versus parent reporters. Methods: We evaluated the utility of the pediatric IA diary through concept elicitation and cognitive interviews with 17 pairs of parents and adolescents (aged 13-17 years) with IA and ADHD, supplemented with 15 new behaviors potentially applicable to adolescents. Results: The behaviors most frequently reported by adolescents included arguing (93.8%), raising their voice/shouting/yelling (93.8%), hitting others (87.5%), slamming (87.5%), pushing/shoving (81.3%), breaking (75.0%), fighting (75.0%), throwing (75.0%), and cursing (68.8%). The behaviors most commonly reported by parents included raising their voice/shouting/yelling (94.1%), arguing (88.2%), being disrespectful/mean/rude (88.2%), slamming (88.2%), throwing (88.2%), cursing (82.4%), hitting others (82.4%), pushing/shoving (82.4%), breaking (76.5%), name-calling (76.5%), and threatening (70.6%). Of all commonly reported behaviors, only being "disrespectful/mean/rude" and "breaking" are not part of the pediatric IA diary, likely due to the imprecision of these terms. No significant usability issues were found for the IA diary device. Conclusions: These findings suggest that the 15-item pediatric IA diary should be applicable to adolescent populations to appropriately characterize IA behaviors in individuals with ADHD. Furthermore, this study indicated that parents may be more reliable reporters of IA behavior than adolescents.

A proposed anti-maladaptive aggression agent classification: improving our approach to treating impulsive aggression.

Proper drug categorization enables clinicians to readily identify the agents most appropriate for patients in need. Currently, patients with maladaptive aggression do not all always fall into a single existing diagnostic or treatment category. Such is the case for those with impulsive aggression (IA). IA is an associated feature of numerous neuropsychiatric disorders, and can be described as eruptive, aggressive behavior or a 'short fuse'. Although agents from a broad spectrum of drug classes have been used to treat maladaptive aggression, few have been tested distinctly in patients with IA, and there is no drug specifically indicated by the US Food and Drug Administration (US FDA) for IA. Further, current treatments often fail to sufficiently treat IA symptomatology. These issues create an unclear and inadequate treatment path for patients. Here we will propose the establishment of a class of anti-maladaptive aggression agents to begin addressing this clinical issue. The development of such a class would unify the various drugs currently used to treat maladaptive aggression and streamline the treatment approach towards IA. As an important case example of the range of candidate drugs that could fit into a new anti-maladaptive aggression agent category, we will review an investigational IA pharmacotherapy. SPN-810 (extended-release molindone) is currently being investigated as a novel treatment for children with IA and ADHD. Based on these studies we will review how SPN-810 may be well suited for a new, anti-maladaptive aggression drug class and more precisely, a proposed subgroup of IA modulators. The goal of this review is to begin improving the identification of and therapeutic approach for maladaptive aggression as well as IA through more precise anti-maladaptive aggression agent categorization.

Perinatal kynurenine 3-hydroxylase inhibition in rodents: pathophysiological implications.

The kynurenine pathway (KP) of tryptophan degradation contains three neuroactive metabolites: the neuroinhibitory agent kynurenic acid (KYNA) and, in a competing branch, the free radical generator 3-hydroxykynurenine (3-HK) and the excitotoxin quinolinic acid (QUIN). These three "kynurenines" derive from a common precursor, L-kynurenine, and are recognized for their role in brain physiology and pathophysiology. Inhibition of kynurenine 3-hydroxylase, the enzyme responsible for 3-HK formation, shifts KP metabolism in the mature brain toward enhanced KYNA formation. We now tested the cerebral effects of kynurenine 3-hydroxylase inhibition in immature rodents. Rat pups treated with the kynurenine 3-hydroxylase inhibitor UPF 648 (30 mg/kg, i.p.) 10 min after birth showed substantial increases in cerebral and liver kynurenine and KYNA levels up to 24 hr later, whereas 3-HK and QUIN levels were simultaneously decreased. Administered to pregnant rats or mice on the last day of gestation, UPF 648 (50 mg/kg, i.p.) produced qualitatively similar changes (i.e., large increases in kynurenine and KYNA and reductions in 3-HK and QUIN) in the brain and liver of the offspring. Rat pups delivered by UPF 648-treated mothers and immediately exposed to neonatal asphyxia showed further enhanced brain KYNA levels. These studies demonstrate that acute kynurenine 3-hydroxylase inhibition effectively shifts cerebral KP metabolism in neonatal rodents toward increased KYNA formation. Selective inhibitors of this enzyme may therefore provide neuroprotection in newborns and will also be useful for the experimental evaluation of the long-term effects of perinatal KP impairment.