OLANZAPINE PLASMA-CONCENTRATIONS AND CLINICAL-RESPONSE IN ACUTELY ILLSCHIZOPHRENIC-PATIENTS

Olanzapine is an atypical antipsychotic effective in the treatment of- schizophrenic patients. After a 2- to 9-day placebo lead-in, 79 inpati ents with schizophrenia according to DSM-III-R criteria were placed on an olanzapine dosage of 10 mg/day or 1 mg/day for up to 6 weeks. Bloo d samples mere obtained meekly during this period. Receiver operating characteristic curve analyses of Brief Psychiatric Rating Scale (BPRS) and Positive and Negative Syndrome Scale rating scale data suggested a minimum effective therapeutic concentration of 9 ng/ml. Using an int ent-to treat analysis, 45% of the patients with olanzapine plasma conc entrations greater than or equal to 9.3 ng/mL responded (greater than or equal to 20% decrease in BPRS), whereas only 13% of the patients wi th concentrations <9.3 ng/mL responde, Use of olanzapine plasma, conce ntrations of >9 ng/mL as a predictor for treatment response in acutely ill schizophrenic patients is practicable because this therapeutic ma rker significantly increases the likelihood of a patient responding to olanzapine.