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.