Therapeutic drug monitoring and objective symptom rating for optimization of antipsychotic drug therapy

Therapeutic drug monitoring (TDM) and objective symptom rating are considered to be useful to optimize antipsychotic drug therapy. The aim of this prospective study was to analyze if serum concentrations and/or improvement according to Clinical Global Impressions (CGI-I) or Brief Psychiatric Rating Scale (BPRS) on week two of treatment have predictive validity for clinical improvement on week 5. The study included 80 schizophrenic patients treated under naturalistic conditions with the atypical antipsychotic drugs amisulpride, aripiprazole, clozapine, olanzapine, quetiapine, risperidone or ziprasidone. Of the 48 patients who exhibited at least moderate improvement on week 2, only 2 patients were impaired on week 5. Of the 42 patients with only slight improvement or less on week two, 51% changed to at least moderately improved on week 5. For these patients improvement was not significantly different between patients with serum concentrations within the therapeutic range and patients with too low or too high serum levels of the antipsychotic drug. The results indicate that improvement according to the CGI-I and even better to BPRS is predictive for later improvement. It is concluded that TDM guided antipsychotic treatment should be accompanied by regular objective symptom rating for optimization of clinical outcome.