Olanzapine versus placebo and haloperidol: acute phase results of the North American double-blind olanzapine trial

Neuropsychopharmacology. 1996 Feb;14(2):111-23. doi: 10.1016/0893-133X(95)00069-P.


Olanzapine is a potential new "atypical" antipsychotic agent. The double-blind acute phase of this study compared three dosage ranges of olanzapine (5 +/- 2.5 mg/day [Olz-L], 10 +/- 2.5 mg/day [Olz-M], 15 +/- 2.5 mg/day [Olz-H]) to a dosage range of haloperidol (15 +/- 5 mg/day [Hal]) and to placebo in the treatment of 335 patients who met the DSM-III-R criteria for schizophrenia. In overall symptomatology improvement (Brief Psychiatric Rating Scale [BPRS]-total), Olz-M, Olz-H, and Hal were significantly superior to placebo. In positive symptom improvement (BPRS-positive), Olz-M, Olz-H, and Hal were comparable and significantly superior to placebo. In negative symptom improvement (Scale for the Assessment of Negative Symptoms [SANS]-composite), Olz-L and Olz-H were significantly superior to placebo and Olz-H was also significantly superior to Hal. The most common treatment-emergent adverse events included somnolence, agitation, asthenia, and nervousness. No acute dystonia was observed with olanzapine. Treatment-emergent parkinsonism occurred with Olz-H at approximately one-third the rate of Hal, and akathisia occurred with Olz-H at approximately one-half the rate of Hal. Prolactin elevations associated with olanzapine were not significantly greater than those observed with placebo and were also significantly less than those seen with haloperidol.

Publication types

  • Clinical Trial
  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Akathisia, Drug-Induced / epidemiology
  • Antipsychotic Agents / administration & dosage
  • Antipsychotic Agents / adverse effects
  • Antipsychotic Agents / therapeutic use*
  • Benzodiazepines
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Dyskinesia, Drug-Induced / epidemiology
  • Female
  • Haloperidol / administration & dosage
  • Haloperidol / adverse effects
  • Haloperidol / therapeutic use*
  • Humans
  • Male
  • Middle Aged
  • Olanzapine
  • Pirenzepine / administration & dosage
  • Pirenzepine / adverse effects
  • Pirenzepine / analogs & derivatives*
  • Pirenzepine / therapeutic use
  • Psychiatric Status Rating Scales
  • Schizophrenia / drug therapy*


  • Antipsychotic Agents
  • Benzodiazepines
  • Pirenzepine
  • Haloperidol
  • Olanzapine