Therapeutic drug monitoring of children and adolescents treated with aripiprazole: observational results from routine patient care.

Although aripiprazole is one of the most used antipsychotics, knowledge about serum concentrations in children and adolescents is scarce and age-specific therapeutic ranges have not been established yet. Data of a routine therapeutic drug monitoring service were analyzed in order to evaluate the relationship between dose and serum concentration of aripiprazole in children and adolescents. The study also aimed to evaluate whether the therapeutic reference range defined for adults with schizophrenia (100-350 ng/ml) is applicable for minors. Data from 130 patients (aged 7-19 years) treated with aripiprazole for different indications in doses of 2-30 mg/day were evaluated. Patient characteristics, doses, serum concentrations and therapeutic outcome were assessed by standardized measures. A positive mean correlation between body weight-corrected daily dose and aripiprazole concentration was found (r = 0.59, p < 0.001) with variation in dose explaining 35% of the variability in serum concentrations. Girls had on average 41% higher dose-corrected concentrations than boys (244.9 versus 173.4 mg/l; p = 0.006). Aripiprazole concentrations did not vary with co-medication (p = 0.22). About 70% of all measured serum concentrations were within the recommended therapeutic range for adults. Using a calculation method in all responding patients with an ICD-10 F2 diagnosis for a rough estimation of a preliminary therapeutic window also demonstrated a similar therapeutic range of aripiprazole in minors (105.9-375.3 ng/ml) than for adults. If confirmed in larger samples and more controlled study designs, these data may contribute to the definition of a therapeutic range of aripiprazole concentrations in children and adolescents.