Olanzapine optimal dose: results of an open-label multicenter study in schizophrenic patients. Olanzapine Late-Phase II Study Group

This open-label clinical study was conducted for patients with schizophrenia in order to investigate the efficacy, safety and optimal dose of olanzapine. One hundred and fifty-six of the 159 enrolled patients were included in the analysis set. For the primary efficacy measure, the Final Global Improvement Rating (FGIR) score, 15.4% of patients had remarkable improvement, 58.3% of patients had moderate improvement or more, 79.5% of patients had slight improvement or more, and 10.3% of patients had increase in disease symptomatology (worsening). Results from the Brief Psychiatric Rating Scale (BPRS) in all individual items were improved from baseline. Olanzapine was effective not only against positive psychotic symptoms but also against negative symptoms. This was consistent with results from the Positive and Negative Syndrome Scale (PANSS). For the majority of patients, a dose range of 7.5-10.0mg/day, as a lower bound on the minimally effective dose, was suggested by the results of the dose to first response based on improvement in Global Improvement Rating (GIR) analyses. The ratio of olanzapine dose to equivalent haloperidol dose was estimated at 1.2 :1. The most commonly reported treatment-emergent signs and symptoms (TESS) occurring at a frequency of 10% or more were insomnia, weight increase, excitement, sleepiness, anxiety, malaise and dull headaches. There was a low incidence of extrapyramidal treatment-emergent signs and symptoms; the most commonly reported were akathisia (6.4%), tremor (5.8%) and muscle rigidity (2.6%).