Olanzapine plasma concentrations and clinical response in acutely ill schizophrenic patients

J Clin Psychopharmacol. 1997 Dec;17(6):472-7. doi: 10.1097/00004714-199712000-00006.


Olanzapine is an atypical antipsychotic effective in the treatment of schizophrenic patients. After a 2- to 9-day placebo lead-in, 79 inpatients 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. Blood samples were obtained weekly 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 intent-to treat analysis, 45% of the patients with olanzapine plasma concentrations > or = 9.3 ng/mL responded (> or = 20% decrease in BPRS), whereas only 13% of the patients with concentrations < 9.3 ng/mL responded. Use of olanzapine plasma concentrations of > 9 ng/mL as a predictor for treatment response in acutely ill schizophrenic patients is practicable because this therapeutic marker significantly increases the likelihood of a patient responding to olanzapine.

Publication types

  • Clinical Trial
  • Comparative Study
  • Controlled Clinical Trial
  • Multicenter Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Antipsychotic Agents / blood*
  • Antipsychotic Agents / therapeutic use*
  • Benzodiazepines
  • Female
  • Humans
  • Male
  • Middle Aged
  • Olanzapine
  • Pirenzepine / analogs & derivatives*
  • Pirenzepine / blood
  • Pirenzepine / therapeutic use
  • Schizophrenia / drug therapy*


  • Antipsychotic Agents
  • Benzodiazepines
  • Pirenzepine
  • Olanzapine