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.</p

DosEmi study protocol: a phase IV, multicentre, open-label, crossover study to evaluate non-inferiority of pharmacokinetic-guided reduced dosing compared with conventional dosing of emicizumab in people with haemophilia A

INTRODUCTION: Emicizumab effectively prevents bleeding in people with haemophilia A (PwHA), but is a burden for national healthcare budgets and consequently may limit access. According to the drug label, dosing of emicizumab is based on body weight with fixed intervals of 7, 14 or 28 days, which leads to mean plasma concentrations of 55 µg/mL (SD 15 µg/mL). However, a moderate variability of concentrations and a minimal effective concentration of 30 µg/mL have been suggested in studies. Therefore, a dose of emicizumab that targets a trough concentration of 30 µg/mL is hypothesised to be equally effective as conventional dosing in the prevention of bleeding. METHODS AND ANALYSIS: We designed a phase IV, multicentre, open-label, crossover study to evaluate non-inferiority of bleed control of ≥6 months on conventional dosing in comparison to ≥6 months on dose intervention. This dose intervention consists of reducing the dose of emicizumab to target a trough concentrations of 30 µg/mL using individual pharmacokinetic (PK) parameters. Ninety-five PwHA aged >1 years who received conventional dosing of emicizumab for ≥12 months with good bleeding control during the last 6 months will be recruited from all Dutch haemophilia treatment centres. The study is powered to detect a clinically relevant decrease (risk difference) of 15% in the proportion of patients without treated bleeds during follow-up. Secondary endpoints are spontaneous joint or muscle bleeds, and annualised treated bleeding rates (using negative binomial regression). Cost-effectivity between conventional dosing and individualised PK-guided dosing of emicizumab will be compared. ETHICS AND DISSEMINATION: The DosEmi study was approved by the Medical Ethics Review Committee NedMec of the University Medical Center of Utrecht, The Netherlands. Study results will be communicated through publications in international scientific journals and presentations at (inter)national conferences. TRIAL REGISTRATION NUMBER: EUCTR2021-004039-10-NL at https://trialsearch.who.int. PROTOCOL VERSION: V.4.1 on 28 October 2022 (DosEmi protocol_V4.1; NL81112.041.22)

Clinical Characteristics of Inpatients with Childhood vs. Adolescent Anorexia Nervosa

We aimed to compare the clinical data at first presentation to inpatient treatment of children (<14 years) vs. adolescents (≥14 years) with anorexia nervosa (AN), focusing on duration of illness before hospital admission and body mass index (BMI) at admission and discharge, proven predictors of the outcomes of adolescent AN. Clinical data at first admission and at discharge in 289 inpatients with AN (children: n = 72; adolescents: n = 217) from a German multicenter, web-based registry for consecutively enrolled patients with childhood and adolescent AN were analyzed. Inclusion criteria were a maximum age of 18 years, first inpatient treatment due to AN, and a BMI <10th BMI percentile at admission. Compared to adolescents, children with AN had a shorter duration of illness before admission (median: 6.0 months vs. 8.0 months, p = 0.004) and higher BMI percentiles at admission (median: 0.7 vs. 0.2, p = 0.004) as well as at discharge (median: 19.3 vs. 15.1, p = 0.011). Thus, in our study, children with AN exhibited clinical characteristics that have been associated with better outcomes, including higher admission and discharge BMI percentile. Future studies should examine whether these factors are actually associated with positive long-term outcomes in children

Therapeutic drug monitoring in adolescents with anorexia nervosa for safe treatment with adjunct olanzapine

Objective: Medication is commonly used in anorexia nervosa (AN) despite largely missing high grade evidence. Olanzapine (OLZ) is the best-evidenced substance used off-label in this group, with conflicting outcome regarding BMI, clinical and safety parameters. Therefore, it is important to strictly assure quality of treatment with OLZ in AN by using 'Therapeutic Drug Monitoring' according to AGNP-guidelines, including serum levels and adverse drug reactions (ADRs) to support safety for adolescents with AN and attempt to generate an initial age- and disorder-specific therapeutic reference range. Method: Sixty-five adolescents with AN (aged 10-18) treated with OLZ (98% female; 97.5% AN-restricting-type) were prospectively observed, ADRs reported, and correlations between dosage and serum levels measured at trough level were calculated, a preliminary therapeutic range defined. Results: Mean dosage of OLZ was 8.15 (SD: 2.91) mg and 0.19 (SD: 0.07) mg/kg respectively, average concentration was 26.57 (SD: 13.46) ng/mL. Correlation between daily dosage/dosage per kg and serum level was 0.72 (**p < 0.001)/0.65 (**p < 0.001), respectively. ADRs with impairment were rare (6.3%). 75% improved clinically (CGI). BMI increased significantly by 1.5 kg/m2 (t = 10.6, p < 0.001). A preliminary therapeutic reference range is 11.9 and 39.9 ng/mL. Conclusions: OLZ in the hands of specialists is a well-tolerated and safe treatment adjunct for adolescents with AN

Seasonal variation of BMI at admission in German adolescents with anorexia nervosa

Objective Recent preliminary studies indicated a seasonal association of BMI at admission to inpatient treatment for anorexia nervosa (AN), indicating lower BMI in the cold season for restrictive AN. An impaired thermoregulation was proposed as the causal factor, based on findings in animal models of AN. However, findings regarding seasonality of BMI and physical activity levels in the general population indicate lower BMI and higher physical activity in summer than in winter. Therefore, we aimed to thoroughly replicate the findings regarding seasonality of BMI at admission in patients with AN in this study. Method AN subtype, age- and gender-standardized BMI scores (BMI-SDS) at admission, mean daily sunshine duration and ambient temperature at the residency of 304 adolescent inpatients with AN of the multi-center German AN registry were analyzed. Results A main effect of DSM-5 AN subtype was found (F(2,298) = 6.630, p = .002), indicating differences in BMI-SDS at admission between restrictive, binge/purge and subclinical AN. No main effect of season on BMI-SDS at admission was found (F(1,298) = 4.723, p = .025), but an interaction effect of DSM-5 subtype and season was obtained (F(2,298) = 6.625, p = .001). Post-hoc group analyses revealed a lower BMI-SDS in the warm season for restrictive AN with a non-significant small effect size (t(203.16) = 2.140, p = .033; Hedges′g = 0.28). Small correlations of mean ambient temperature (r = −.16) and daily sunshine duration (r = −.22) with BMI-SDS in restrictive AN were found. However, the data were widely scattered. Conclusions Our findings are contrary to previous studies and question the thermoregulatory hypothesis, indicating that seasonality in AN is more complex and might be subject to other biological or psychological factors, for example physical activity or body dissatisfaction. Our results indicate only a small clinical relevance of seasonal associations of BMI-SDS merely at admission. Longitudinal studies investigating within-subject seasonal changes might be more promising to assess seasonality in AN and of higher clinical relevance

Serious Adverse Drug Reactions in Children and Adolescents Treated On- and Off-Label with Antidepressants and Antipsychotics in Clinical Practice

Introduction: Despite the growing evidence base for psychotropic drug treatment in pediatric patients, knowledge about the benefit-risk ratio in clinical practice remains limited. The 'Therapeutic Drug Monitoring (TDM)-VIGIL' study aimed to evaluate serious adverse drug reactions (ADRs) in children and adolescents treated with antidepressants and/or antipsychotics in approved ('on-label'), and off-label use in clinical practice. Methods: Psychiatric pediatric patients aged 6-18 years treated with antidepressants and/or antipsychotics either on-label or off-label were prospectively followed between October 2014 and December 2018 within a multicenter trial. Follow-up included standardized assessments of response, serious ADRs and therapeutic drug monitoring. Results: 710 youth (age=14.6±2.2 years, female=66.6%) were observed for 5.5 months on average; 76.3% received antidepressants, 47.5% antipsychotics, and 25.2% both. Altogether, 55.2% of the treatment episodes with antidepressants and 80.7% with antipsychotics were off-label. Serious ADRs occurred in 8.3% (95%CI=6.4-10.6%) of patients, mainly being psychiatric adverse reactions (77.4%), predominantly suicidal ideation and behavior. The risk of serious ADRs was not significantly different between patients using psychotropics off-label and on-label (antidepressants: 8.1% vs. 11.3%, p=0.16; antipsychotics: 8.7% vs 7.5%, p=0.67). Serious ADRs occurred in 16.6% of patients who were suicidal at enrollment versus 5.6% of patients who were not suicidal (relative risk 3.0, 95%CI=1.9-4.9). Conclusion: Off-label use of antidepressants and antipsychotics in youth was not a risk factor for the occurrence of serious ADRs in a closely monitored clinical setting. Results from large naturalistic trials like ours can contribute to bridging the gap between knowledge from randomized controlled trials and real-world clinical settings

Therapeutic drug monitoring of sertraline in children and adolescents: A naturalistic study with insights into the clinical response and treatment of obsessive-compulsive disorder.

BACKGROUND Sertraline is a selective serotonin reuptake inhibitor with specific indications in child and adolescent psychiatry. Notwithstanding its frequent use and clinical benefits, the relationship between pharmacokinetics, pharmacodynamics, efficacy, and tolerability of sertraline across indications, particularly in non-adult patients, is not fully understood. METHOD This naturalistic therapeutic drug monitoring (TDM) study was conducted in a transdiagnostic sample of children and adolescents treated with sertraline (n = 78; mean age, 14.22 ± 2.39; range, 7-18 years) within the prospective multicenter "TDM-VIGIL" project. Associations between dose, serum concentration, and medication-specific therapeutic and side effects based on the Clinical Global Impression scale were examined. Tolerability was measured qualitatively with the 56-item Pediatric Adverse Event Rating Scale. RESULTS A strong linear positive dose-serum concentration relationship (with dose explaining 45% of the variance in concentration) and significant effects of weight and co-medication were found. Neither dose nor serum concentration were associated with side effects. An overall mild-to-moderate tolerability profile of sertraline was observed. In contrast with the transdiagnostic analysis that did not indicate an effect of concentration, when split into depression (MDD) and obsessive-compulsive disorder (OCD) diagnoses, the probability of clinical improvement significantly increased as both dose and concentration increased for OCD, but not for MDD. CONCLUSIONS This TDM-flexible-dose study revealed a significant diagnosis-specific effect between sertraline serum concentration and clinical efficacy for pediatric OCD. While TDM already guides clinical decision-making regarding compliance, dose calibration, and drug-drug interactions, combining TDM with other methods, such as pharmacogenetics, may facilitate a personalized medicine approach in psychiatry

Therapeutic Drug Monitoring in Children and Adolescents: Findings on Fluoxetine from the TDM-VIGIL Trial

Fluoxetine is the recommended first-line antidepressant in many therapeutic guidelines for children and adolescents. However, little is known about the relationships between drug dose and serum level as well as the therapeutic serum reference range in this age group. Within a large naturalistic observational prospective multicenter clinical trial (“TDM-VIGIL”), a transdiagnostic sample of children and adolescents (n = 138; mean age, 15; range, 7–18 years; 24.6% males) was treated with fluoxetine (10–40 mg/day). Analyses of both the last timepoint and all timepoints (n = 292 observations), utilizing (multiple) linear regressions, linear mixed-effect models, and cumulative link (mixed) models, were used to test the associations between dose, serum concentration, outcome, and potential predictors. The receiver operating curve and first to third interquartile methods, respectively, were used to examine concentration cutoff and reference values for responders. A strong positive relationship was found between dose and serum concentration of fluoxetine and its metabolite. Higher body weight was associated with lower serum concentrations, and female sex was associated with lower therapeutic response. The preliminary reference ranges for the active moiety (fluoxetine+norfluoxetine) were 208–328 ng/mL (transdiagnostically) and 201.5–306 ng/mL (depression). Most patients showed marked (45.6%) or minimal (43.5%) improvements and reported no adverse effects (64.9%). This study demonstrated a clear linear dose–serum level relationship for fluoxetine in youth, with the identified reference range being within that established for adults

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