Serum Concentrations, Therapeutic Response and Side Effects in Children and Adolescents with Impulsive-Aggressive Symptoms during Risperidone Therapy

Therapeutic Drug Monitoring to Optimize Risperidone Treatment in Children with Autism Spectrum Disorder

BACKGROUND

Risperidone is an atypical antipsychotic drug used to treat irritability and aggression in children and adolescents with autism spectrum disorder. In an earlier study, the sum trough concentration of risperidone and its metabolite (9-hydroxyrisperidone) was positively correlated with weight gain and effectiveness. The aim of this study was to determine the therapeutic window for risperidone sum trough concentrations that balances weight gain with treatment effectiveness in this population. In addition, the effect of therapeutic drug monitoring (TDM) on treatment optimization was simulated.

METHODS

In a retrospective cohort (n = 24 children), the target window for risperidone leading to the least increase in body mass index z-scores while retaining effectiveness as measured by the irritability subscale of the Aberrant Behavior Checklist was determined using receiver operating curve analysis. This target range was used to simulate the effect of TDM using a population PK model implemented in the software platform InsightRX. Dosing advice was based on plasma trough concentrations and the dose administered at 12 weeks to simulate whether more children would be on target at 24 weeks after the start of treatment.

RESULTS

A risperidone sum trough target range of 3.5-7.0 mcg/L would minimize increase in body mass index z-score and optimize effectiveness. Dosing advice using TDM and a population PK model would lead to a larger proportion of children achieving the target concentration range (62.5% versus 16.7%).

CONCLUSIONS

TDM may be a useful tool for optimizing risperidone treatment in children and adolescents with autism spectrum disorder.

Clinical pharmacokinetics of antipsychotics in pediatric populations: a scoping review focusing on dosing regimen

INTRODUCTION

Achieving optimal clinical responses and minimizing side effects through precision dosing of antipsychotics in children and adolescents with psychiatric disorders remains a challenge. Identifying patient characteristics (covariates) that affect pharmacokinetics can inform more effective dosing strategies and ultimately improve patient outcomes. This review aims to provide greater insight into the impact of covariates on the clinical pharmacokinetics of antipsychotics in pediatric populations.

AREAS COVERED

A comprehensive literature search was conducted, and the main findings regarding the effects of the covariates on the pharmacokinetics of antipsychotics in children and adolescents are presented.

EXPERT OPINION

Our study highlights significant covariates, including age, sex, weight, CYP2D6 phenotype, co-medication, and smoking habits, which affect the pharmacokinetics of antipsychotics. However, the findings were generally limited by the small sample sizes of naturalistic, open-label, observational studies, and the homogeneous subgroups. Dosing based on weight and preemptive genotyping could prove beneficial for optimizing the dosing regimen in pediatric populations. Future research is needed to refine dosing recommendations and establish therapeutic reference ranges critical for precision dosing and Therapeutic Drug Monitoring (TDM). The integration of individual patient characteristics with TDM can further optimize the efficacy and safety of antipsychotics for each patient.

Serious Adverse Drug Reactions to Antipsychotics in Minors with Multiple Disabilities: Preventability and Potential Cost Savings by Therapeutic Drug Monitoring

INTRODUCTION

Children and adolescents with multiple disabilities and mental disorders (CAMD) are frequently treated with antipsychotic drugs. However, CAMD are particularly susceptible to serious adverse drug reactions (sADRs). This retrospective study examined the frequency of sADRs to antipsychotics in CAMD. Further, the potential preventability of these sADRs through therapeutic drug monitoring (TDM) and the potential socio-economic benefits of TDM were explored.

METHODS

Routine clinical data of all patients treated at a specialized psychiatric clinic for CAMD between January 2017 and December 2018 were retrospectively examined. Data on the occurrence of sADRs (definition according to the European Medicines Agency), their causality with antipsychotics, as well as their preventability (Schumock criteria) were extracted from patient files. The prolongation of the hospital stay due to sADRs was calculated, and the cost savings were estimated if TDM had been applied. The data were based on a subsample of the KiDSafe project, supported by the Innovation Fund of the Joint Federal Committee, grant number 01NVF16021.

RESULTS

One hundred two CAMD who were administered at least one antipsychotic drug during inpatient treatment were identified. Of these patients, 22 (21.6%) sADRs with a possible causal relationship with the antipsychotic treatment were documented. Eleven sADRs (50%) could potentially have been prevented through TDM. Mitigating sADRs through TDM likely would have prevented prolonged hospital stays and thus conferred considerable savings for health insurance companies.

DISCUSSION

The routine implementation of TDM is urgently recommended for antipsychotic treatment in CAMD to increase drug therapy safety.

Therapeutic drug monitoring of atomoxetine in children and adolescents with attention-deficit/ hyperactivity disorder: a naturalistic study

The selective norepinephrine reuptake inhibitor atomoxetine is potentially among the first-line pharmacotherapy options for ADHD. Therapeutic drug monitoring (TDM) with the quantification and interpretation of atomoxetine serum concentrations is used to determine an individual dose followed by an optimal effectiveness and minimal side effects. The aim of this retrospective pharmacokinetic–pharmacodynamic analysis was to derive age-appropriate recommendations for the implementation of TDM to improve the efficacy and tolerability of atomoxetine in children and adolescents. Using the analytical method of high-performance liquid chromatography with UV detection, 94 serum concentrations of 74 patients between 6 and 21 years of age were determined. Therapeutic effectiveness and side effects were evaluated according to the categories “low”, “moderate”, and “significant”. As part of TDM, a time interval with maximum concentrations of 1–3 h after the administration of atomoxetine was determined for blood sampling. In this time interval, a significant correlation between the weight-normalized dose and the serum concentrations was found. The efficacy as well as the tolerability proved to be mainly moderate or significant. A preliminary therapeutic reference range was between 100 and 400 ng/ml. Naturalistic studies have limitations. Therefore, and due to a limited study population, the results have to be regarded as preliminary observations that must be confirmed in further studies. The preliminary therapeutic reference range for children and adolescents proved to be narrower than the reference range for adult patients. However, due to good efficacy and tolerability an exact reference range remained difficult to determine.

Therapeutic drug monitoring in children and adolescents with schizophrenia and other psychotic disorders using risperidone

Risperidone is commonly used to treat different psychiatric disorders worldwide. Knowledge on dose–concentration relationships of risperidone treatment in children and adolescents with schizophrenia or other psychotic disorders is, however, scarce and no age-specific therapeutic ranges have been established yet. Multicenter data of a therapeutic drug monitoring service were analyzed to evaluate the relationship between risperidone dose and serum concentration of the active moiety (risperidone (RIS) plus its main metabolite 9-hydroxyrisperidone (9-OH-RIS)) in children and adolescents with psychotic disorders. Patient characteristics, doses, serum concentrations and therapeutic outcomes were assessed by standardized measures. The study also aimed to evaluate whether the therapeutic reference range for adults (20–60 ng/ml) is applicable for minors. In the 64 patients (aged 11–18 years) included, a positive correlation between daily dose and the active moiety (RIS_am) concentration was found (r_s = 0.49, p = 0.001) with variation in dose explaining 24% (r_s² = 0.240) of the variability in serum concentrations. While the RIS_am concentration showed no difference, RIS as well 9-OH-RIS concentrations and the parent to metabolite ratio varied significantly in patients with co-medication of a CYP2D6 inhibitor. Patients with extrapyramidal symptoms (EPS) had on average higher RISam concentrations than patients without (p = 0.05). Considering EPS, the upper threshold of the therapeutic range of RIS_am was determined to be 33 ng/ml. A rough estimation method also indicated a possibly decreased lower limit of the preliminary therapeutic range in minors compared to adults. These preliminary data may contribute to the definition of a therapeutic window in children and adolescents with schizophrenic disorders treated with risperidone. TDM is recommended in this vulnerable population to prevent concentration-related adverse drug reactions.

Dose-Corrected Serum Concentrations and Metabolite to Parent Compound Ratios of Venlafaxine and Risperidone from Childhood to Old Age

OBJECTIVE

Comparative pharmacokinetic data about the antidepressant venlafaxine (VEN) and the antipsychotic drug risperidone (RIS) over the lifespan and especially in children and adolescents is lacking. This is the first cross-sectional study that aimed to investigate differences in dose-corrected serum concentrations (CDs) and metabolite to parent compound ratios (MPRs) of VEN and RIS across the lifespan.

METHODS

Patients treated with VEN and RIS at the University Hospital of Würzburg, Germany were included in the study. Serum level determinations were performed during clinical routine care. Patients with CYP2D6 influencing co-medication were excluded from analyses.

RESULTS

In 953 patients (12-93 years) treated with VEN and 552 patients (7-92 years) treated with RIS, children/adolescents (<18 years) showed 11% and 19%, and 44% and 42% lower CDs of the active moieties (CDs_AM) of VEN and RIS than adults and elderly (≥60 years) (Kruskal-Wallis tests; p ≤ 0.001). However, when CDs were normalized to body weight, a different pattern emerged. Gender differences, with higher CDs_AM in females were present in adults and elderlies but not in children/adolescents. No gender- or age-dependent difference in MPRs was found; however, 80% of MPRs of RIS in children/adolescents were below the range of "normal" CYP2D6 function for adults.

CONCLUSIONS

We suggest a higher clearance as a reason for lower CDs_AM of VEN and RIS in children/adolescents compared to adults/elderlies. Metabolism of VEN or RIS by CYP2D6, characterized by MPRs, was not associated with age. However, MPRs of RIS were lower in children/adolescents, possibly due to a higher renal clearance of 9-OH-risperidone.

Risperidone plasma concentrations are associated with side effects and effectiveness in children and adolescents with autism spectrum disorder

AIM

Risperidone is the most commonly prescribed antipsychotic drug to children and adolescents worldwide, but it is associated with serious side effects, including weight gain. This study assessed the relationship of risperidone and 9-hydroxyrisperidone trough concentrations, maximum concentrations and 24-hour area under the curves (AUCs) with body mass index (BMI) z-scores in children and adolescents with autism spectrum disorder (ASD) and behavioural problems. Secondary outcomes were metabolic, endocrine, extrapyramidal and cardiac side effects and effectiveness.

METHODS

Forty-two children and adolescents (32 males) aged 6-18 years were included in a 24-week prospective observational trial. Drug plasma concentrations, side effects and effectiveness were measured at several time points during follow-up. Relevant pharmacokinetic covariates, including medication adherence and CYP2D6, CYP3A4, CYP3A5 and P-glycoprotein (ABCB1) genotypes, were measured. Nonlinear mixed-effects modelling (NONMEM®) was used for a population pharmacokinetic analysis with 205 risperidone and 205 9-hydroxyrisperidone concentrations. Subsequently, model-based trough concentrations, maximum concentrations and 24-hour AUCs were analysed to predict outcomes using generalized and linear mixed-effects models.

RESULTS

A risperidone two-compartment model combined with a 9-hydroxyrisperidone one-compartment model best described the measured concentrations. Of all the pharmacokinetic parameters, higher risperidone sum trough concentrations best predicted higher BMI z-scores during follow-up (P < .001). Higher sum trough concentrations also predicted more sedation (P < .05), higher prolactin levels (P < .001) and more effectiveness measured with Aberrant Behavior Checklist irritability score (P < .01).

CONCLUSION

Our results indicate a therapeutic window exists, which suggests that therapeutic drug monitoring of risperidone might increase safety and effectiveness in children and adolescents with ASD and behavioural problems.

Psychotropic drug concentrations and clinical outcomes in children and adolescents: a systematic review

INTRODUCTION

The use of psychotropic drugs in children and adolescents is widespread but associated with suboptimal treatment effects. Therapeutic drug monitoring (TDM) can improve safety of psychotropic drugs in children and adolescents but is not routinely performed. A major reason is that the relationship between drug concentrations and effects is not well known.

AREAS COVERED

This systematic review evaluated studies assessing the relationship between psychotropic drug concentrations and clinical outcomes in children and adolescents, including antipsychotics, psychostimulants, alpha-agonists, antidepressants, and mood-stabilizers. PRISMA guidelines were used and a quality assessment of the retrieved studies was performed. Sixty-seven eligible studies involving 24 psychotropic drugs were identified from 9,298 records. The findings were generally heterogeneous and the majority of all retrieved studies were not of sufficient quality. For 11 psychotropic drugs, a relationship between drug concentrations and side-effects and/or effectiveness was evidenced in reasonably reported and executed studies, but these findings were barely replicated.

EXPERT OPINION

In order to better support routine TDM in child- and adolescent psychiatry, future work must improve in aspects of study design, execution and reporting to demonstrate drug concentration-effect relationships. The quality criteria proposed in this work can guide future TDM research. Systematic review protocol and registration PROSPERO CRD42018084159.

[Polypharmacy of psychotropic drugs in child and adolescent psychiatry in Germany - rather the rule than the exception]

Polypharmacy of psychotropic drugs in child and adolescent psychiatry in Germany - rather the rule than the exception Abstract. Background: Polypharmacy increases the risk of interactions and enhances the chance of adverse drug reactions (ADRs). Hence, child and adolescent psychiatrists generally try to avoid polypharmacy with psychotropic drugs. However, only little data regarding the frequency of polypharmacy in child and adolescent psychiatry are available. This study analyzes clinical data on polypharmacy and the possible association with a higher risk of ADRs in Germany, with a focus on antidepressants and antipsychotics. Methods: We investigated a total of 940 datasets from descriptive studies on therapeutic drug monitoring (TDM) of pediatric patients treated with different psychotropic drugs. Results: The frequency of polypharmacy ranged up to 45.6 % (escitalopram) and 72.1 % (olanzapine). In 17.4 % of the cases, polypharmacy consisted of four or more psycho-/neuropharmacological substances. No increased incidence of ADRs was reported with polypharmacy of antipsychotics compared to monotherapy. Polypharmacy with sertraline was associated with a higher number of ADRs. Discussion and Conclusion: There is a high prevalence of polypharmacy with psychotropic drugs in child and adolescent psychiatry in Germany. Conclusions concerning individual drugs should be drawn with care since the subsample sizes were relatively small. However, our results do provide an indication of the prevalence of polypharmacy, although the validity of the data is limited. There is an urgent need to analyze data from larger and more homogeneous groups under more controlled conditions.

Therapeutic drug monitoring as a measure of proactive pharmacovigilance in child and adolescent psychiatry

INTRODUCTION

Off-label or unlicensed use of psychotropic drugs is common rather than the exception in child and adolescent psychiatry. This use exposes patients to an unknown additional risk of ineffective or even harmful treatment. In addition, treatment with psychotropic drugs during a period of life when the patient undergoes marked developmental hormonal and neurobiological changes often requires different dosing regimes in later life and may result in adverse drug reactions, which are either not seen in adults at all or not in the same frequency. Areas covered: Given these critical safety issues, efficient pharmacovigilance methods as part of routine practice are essential for the improvement of patient care. The purpose of this article is to introduce methods to increase the safety of psychotropic drug use in youngsters. In particular, therapeutic drug monitoring (TDM) as a routine measure of proactive pharmacovigilance is discussed. Expert opinion: Given the special features of psychopharmacological therapy in children and adolescents in day-to-day clinical practise, proactive surveillance by using a close standardized 'patient monitoring' and long-term follow-up with TDM is very important. This approach could minimize the risk of exposing paediatric patients to ineffective treatments of uncertain or unknown risks.

[Pharmacovigilance in child and adolescent psychiatry]

Rational pharmacotherapy is a challenging task in child and adolescent psychiatry. Increasing prescription numbers contrast with the uncertainties of safety and efficacy issues. The lack of clinical (authorization) trials often implies a non- age-specific use of drugs. However, young patients show particular metabolic conditions and a higher vulnerability for adverse drug reactions. Thus it seems mandatory to create age-specific pharmacological data about efficacy and safety of psychotropic drug use in minors. Legislation authorities became aware of this situation and introduced European and national scientific pharmacovigilance regulations and programmes accordingly in order to continuously evaluate the benefit-risk-ratio, detect, collect, minimize, and prevent adverse effects of drugs by appropriate measures, e.g., therapeutic drug monitoring. In this paper the principles and needs of pharmacovigilance in child and adolescent psychiatry are discussed. Furthermore a large multicenter clinical trial («TDM-VIGIL»), funded by the German Federal Institute for Drugs and Medical Devices, is presented, which appeals to collect epidemiological prescription and safety data of psychotropic drugs in children and adolescents using an internet-based data infrastructure (patient registry).

The relation between dosage, serum concentrations, and clinical outcome in children and adolescents treated with sertraline: a naturalistic study

OBJECTIVE

This naturalistic therapeutic drug monitoring (TDM) study aimed to evaluate the relationship between dosage, serum concentration, and clinical outcome in children and adolescents treated with the serotonin reuptake inhibitor sertraline for different indications.

METHODS

Steady-state trough serum concentrations were analyzed in 90 subjects, treated with 25-200 mg sertraline per day. Therapeutic efficacy was assessed by the Clinical Global Impression Improvement subscale and side effects by the Udvalg for Kliniske Undersogelser-Side Effect Rating Scale.

RESULTS

In the study population, children were administered higher body weight normalized daily doses than adolescents. The relationships between sertraline daily dosage and serum concentrations (rs = 0.67, P < 0.0001) as well as between body weight normalized daily doses and serum concentrations (r = 0.62, P < 0.0001) were linear. In the whole patient group, no correlation between serum concentrations and either the therapeutic effect or side effects could be observed, neither significant effects of gender, age, concomitant medications, or smoking habits. When analyzing just the patients with depression, those with side effects had significantly higher sertraline serum concentrations than those without (44.8 ng/mL versus 22.3 ng/mL, P = 0.01). In general, occurrence of side effects was significantly more frequent in patients with psychiatric comedication (37.9%) than those without (11.5%, P = 0.002).

DISCUSSION

As this study has the typical limitations of naturalistic studies, the results should be interpreted cautiously. From the data, it is not possible to suggest an age-specific therapeutic window for children and adolescents. However, as the intraindividual variability of sertraline serum concentrations is known to be low, TDM may certainly help to predict serum concentrations after dose adjustment, to assess pharmacokinetic drug-drug interactions influencing serum concentrations and the patient's compliance, finally allowing for personalizing dose through TDM.

Safety and pharmacokinetics of atypical antipsychotics in children and adolescents

Pediatric behavioral and affective disorders often require antipsychotic therapy, in combination with psychotherapeutic interventions, for their treatment and stabilization. Although pharmacotherapy can include either typical or atypical antipsychotics, the latter are generally preferred because of their apparently lower risk of adverse effects. Recent controlled trials have demonstrated the efficacy of some of these agents (including aripiprazole, clozapine, olanzapine, paliperidone, quetiapine, risperidone, ziprasidone) in adolescent schizophrenia and children or adolescent bipolar mania, or to treat severe aggression and self-injury in the context of autism in children and adolescents. Although few studies have systematically monitored their short- and, more importantly, long-term safety, current evidence indicates that sedation, hyperprolactinemia, and metabolic abnormalities such as excess weight gain, diabetes, and related cardiovascular effects were clinically relevant adverse effects in young patients, with the individual agents differing in their propensity to induce these effects. When prescribing antipsychotics for children and adolescents, physicians should therefore be aware of the specific adverse effect profiles and patients should be closely monitored for the short- and long-term development of adverse events. In pediatric patients, the starting dose, titration plan, and maintenance dose of antipsychotics must be based on their pharmacokinetics and metabolism, as in adults. Because there are significant individual differences in drug and active metabolite(s) pharmacokinetics and metabolism, which may be further affected by a number of confounding factors (including demographic variables, phenotype and drug interactions), therapeutic drug monitoring may be a valid tool for individualizing dosage, but its interpretation should also take account of changes in pharmacodynamic sensitivity with the development during childhood and adolescence.

Atypical antipsychotics: trends in analysis and sample preparation of various biological samples

Atypical antipsychotics are increasingly popular and increasingly prescribed. In some countries, they can even be obtained over-the-counter, without a prescription, making their abuse quite easy. Although atypical antipsychotics are thought to be safer than typical antipsychotics, they still have severe side effects. Intoxications are not rare and some of them have a fatal outcome. Drug interactions involving atypical antipsychotics complicate patient management in clinical settings and the determination of the cause of death in fatalities. In view of the above, analytical strategies that can efficiently isolate atypical antipsychotics from a variety of biological samples and quantify them accurately, sensitively and reliably, are of utmost importance both for the clinical, as well as for the forensic toxicologist. In this review, we will present and discuss novel analytical strategies that have been developed from 2004 to the present day for the determination of atypical antipsychotics in various biological samples.

Risperidone and divalproex differentially engage the fronto-striato-temporal circuitry in pediatric mania: a pharmacological functional magnetic resonance imaging study

OBJECTIVE

The current study examined the impact of risperidone and divalproex on affective and working memory circuitry in patients with pediatric bipolar disorder (PBD).

METHOD

This was a six-week, double-blind, randomized trial of risperidone plus placebo versus divalproex plus placebo for patients with mania (n = 21; 13.6 ± 2.5 years of age). Functional magnetic resonance imaging (fMRI) outcomes were measured using a block design, affective, N-back task with angry, happy, and neutral face stimuli at baseline and at 6-week follow-up. Matched healthy controls (HC; n = 15, 14.5 ± 2.8 years) were also scanned twice.

RESULTS

In post hoc analyses on the significant interaction in a 3×2×2 analysis of variance (ANOVA) that included patient groups and HC, the risperidone group showed greater activation after treatment in response to the angry face condition in the left subgenual anterior cingulate cortex (ACC) and striatum relative to the divalproex group. The divalproex group showed greater activation relative to the risperidone group in the left inferior frontal gyrus and right middle temporal gyrus. Over the treatment course, the risperidone group showed greater change in activation in the left ventral striatum than the divalproex group, and the divalproex group showed greater activation change in left inferior frontal gyrus and right middle temporal gyrus than the risperidone group. Furthermore, each patient group showed increased activation relative to HC in fronto-striato-temporal regions over time. The happy face condition was potentially less emotionally challenging in this study and did not elicit notable findings.

CONCLUSIONS

When patients performed a working memory task under emotional duress inherent in the paradigm, divalproex enhanced activation in a fronto-temporal circuit whereas risperidone increased activation in the dopamine (D₂) receptor-rich ventral striatum. Clinical trial registration information-Risperidone and Divalproex Sodium With MRI Assessment in Pediatric Bipolar; http://www.clinicaltrials.gov; NCT00176202.

An open-label trial of risperidone in children and adolescents with severe mood dysregulation

OBJECTIVE

The diagnosis and treatment of youth with severe nonepisodic irritability and hyperarousal, a syndrome defined as severe mood dysregulation (SMD), has been the focus of increasing concern and debate among clinicians and researchers. Our main objective was to assess the effectiveness of risperidone for youths with SMD.

METHODS

An 8-week open label trial with risperidone was conducted. We extensively assessed 97 subjects with semistructured and clinical interviews and enrolled 21 patients in the study. Risperidone was titrated from 0.5 to 3 mg/day in the first 2 weeks. Evaluations were performed at baseline and weeks 2, 4, 6, and 8. Clinical outcome measures were (1) Aberrant Behavior Checklist-Irritability Subscale, (2) Clinical Global Impressions, and (3) severity of co-morbid conditions.

RESULTS

We found a significant reduction of the Aberrant Behavior Checklist-Irritability scores during the trial after risperidone use (p < 0.001). The scores at week 2 (mean = 12.03; standard error [SE] = 2.94), week 4 (mean = 15.48; SE = 2.93), week 6 (mean = 12.29; SE = 2.86), and week 8 (mean = 11.28; SE = 3.06) were significantly reduced compared with the baseline mean score (mean = 25.89; SE = 2.76) (p < 0.001). We also found an improvement in attention-deficit/hyperactivity disorder, depression, and global functioning (p < 0.001).

CONCLUSION

Risperidone was effective in reducing irritability in SMD youth. To the best of our knowledge, this is the first psychopharmacological trial in this group of patients with positive results. Further randomized, controlled studies are needed.