Therapeutic drug monitoring of aripiprazole

Aripiprazole is a third generation antipsychotic drug with a novel pharmacological profile. Due to high interindividual variability in drug metabolism and compliance, aripiprazole dosing may be optimized by therapeutic drug monitoring (TDM). In this study blood levels of schizophrenic patients were analyzed and related to dose, comedication, drug response and side effects. An automated chromatographic method with column switching was used to analyze plasma concentrations of aripiprazole. For clincial evaluation the Clinical Global Impressions (CGI) and the UKU side effect scales were used. All patients (n=87, 42 women, age 36±13 years) suffered from schizophrenia. 74% of them received comedication which included a second antipsychotic (31%), antidepressants (14%), benzodiazepines (19%) or mood stabilizers (14%) as psychiatric drugs. Trough blood levels of aripiprazole were highly variable between individuals (mean±SD, 282±178 ng/mL, median 244 ng/mL), the 25^th to 75^th percentile range was 150 to 387 ng/mL. They correlated with the dose (r=0,362; P <0,001). Of the patients who received aripiprazole as antipsychotic monotherapy, 27% reported side effects, with sedation being the most frequent one. Plasma concentrations between 150 and 390 ng/ml could be considered as a preliminary target range for clinical improvement with minimal side effects. Evidence is growing that TDM is useful to optimize the treatment of schizophrenic patients with aripiprazole.