Background Antipsychotic drugs are an important part of the treatment of irritability and aggression in children with an autism spectrum disorder (ASD). However, significant weight gain and metabolic disturbances are clinically relevant side effects of antipsychotic use in children. In the SPACe study, we showed positive correlations between both risperidone and aripiprazole plasma trough concentrations and weight gain over a 6-month period. The trial SPACe 2: STAR is designed as a follow-up study, in which we aim to research whether therapeutic drug monitoring in clinical practice can prevent severe weight gain, while retaining clinical effectiveness. Methods SPACe 2: STAR is an international, multicentre, randomised controlled trial (RCT). One hundred forty children aged 6 to 18 who are about to start risperidone or aripiprazole treatment for ASD related behavioural problems will be randomised into one of two groups: a therapeutic drug monitoring (TDM) group, and a care as usual (CAU) group. Participants will be assessed at baseline and 4, 10, 24, and 52 weeks follow-up. In the TDM group, physicians will receive dosing advice based on plasma levels of risperidone and aripiprazole and its metabolites at 4 and 10 weeks. Plasma levels will be measured in dried blood spots (DBS). The primary outcome will be BMI z-score at 24 weeks after start of antipsychotic treatment. Among the secondary outcomes are effectiveness, metabolic laboratory measurements, levels of prolactin, leptin and ghrelin, extrapyramidal side effects, and quality of life. Discussion This will be the first RCT evaluating the effect of TDM of antipsychotic drugs in children and adolescents. Thus, findings from SPACe 2: STAR will be of great value in optimising treatment in this vulnerable population. Trial registration ClinicalTrials.gov Identifier: NCT05146245. EudraCT number: 2020–005450-18. Sponsor protocol name: SPACe2STAR. Registered 8 June 2021. Protocol Version 6, Protocol date: 18 august 2022.

AimsAripiprazole is one of the most commonly prescribed antipsychotic drugs to children and adolescents worldwide, but it is associated with serious side‐effects, including weight gain. This study assessed the population pharmacokinetics of aripiprazole and its active metabolite and investigated the relationship between pharmacokinetic parameters and body mass index (BMI) in children and adolescents with autism spectrum disorder (ASD) and behavioural problems. Secondary outcomes were metabolic, endocrine, extrapyramidal and cardiac side‐effects and drug effectiveness.MethodsTwenty‐four children and adolescents (15 males, 9 females) aged 6–18 years were included in a 24‐week prospective observational trial. Drug plasma concentrations, side‐effects and drug effectiveness were measured at several time points during follow‐up. Relevant pharmacokinetic covariates, including CYP2D6, CYP3A4, CYP3A5 and P‐glycoprotein (ABCB1) genotypes, were determined. Nonlinear mixed‐effects modelling (NONMEM®) was used for a population pharmacokinetic analysis with 92 aripiprazole and 91 dehydro‐aripiprazole concentrations. Subsequently, model‐based trough concentrations, maximum concentrations and 24‐h area under the curves (AUCs) were analysed to predict outcomes using generalized and linear mixed‐effects models.ResultsFor both aripiprazole and dehydro‐aripiprazole, one‐compartment models best described the measured concentrations, with albumin and BMI as significant covariates. Of all the pharmacokinetic parameters, higher sum (aripiprazole plus dehydro‐aripiprazole) trough concentrations best predicted higher BMI z‐scores (P < .001) and higher Hb1Ac levels (P = .03) during follow‐up. No significant association was found between sum concentrations and effectiveness.ConclusionsOur results indicate a threshold with regard to safety, which suggests that therapeutic drug monitoring of aripiprazole could potentially increase safety in children and adolescents with ASD and behavioural problems.

Objective The Dutch law on youth care (the Youth Act) was implemented from 2015 onwards. One of the government’s aims by implementing this new policy was de-medicalization of youths by separating youth mental healthcare from the rest of the healthcare system. A previous study conducted by our research group showed that prevalence rates of antipsychotic drug prescriptions stabilized among Dutch youth in the period 2005–2015, just before the introduction of the Youth Act. In our study, we aimed to describe antipsychotic drug use among Dutch children aged 0–19 years old before and after implementation of the Youth Act (2010–2019). Methods We analyzed prescription data of 7405 youths aged 0–19 years using antipsychotic drugs between 2010 and 2019, derived from a large Dutch community pharmacy-based prescription database (IADB.nl). Results Prevalence rates of antipsychotic drug use per thousand youths decreased significantly in youths aged 7–12 years old in 2019 compared to 2015 (7.9 vs 9.0 p < 0.05). By contrast, prevalence rates increased in adolescent females in 2019 compared to 2015 (11.8 vs 9.5 p < 0.05). Incidence rates increased significantly in adolescent youths in 2019 compared to 2015 (3.9 vs 3.0 p < 0.05), specifically among adolescent girls (4.2 per thousand in 2019 compared to 3.0 per thousand in 2015). Dosages in milligram declined for the most commonly prescribed antipsychotic drugs during the study period. The mean duration of antipsychotic drug use in the study period was 5.7 (95% CI 5.2–6.2) months. Conclusion Despite the aim of the Youth Act to achieve de-medicalization of youths, no clear reduction was observed in prevalence rates of antipsychotic drugs or treatment duration in all subgroups. Prevalence rates even increased in adolescent females.

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