The investigators hypothesis is that an antipsychotic drug combination of low-dose olanzapine plus low-dose trifluoperazine is similar to regular-dose olanzapine monotherapy in efficacy and safety for treatment of schizophrenia.The goal of this study is to compare the efficacy and safety of the olanzapine (10 mg/d) and olanzapine (5 mg/d) plus trifluoperazine (5 mg/d) in the treatment of acute psychotic exacerbations of schizophrenia.

Antipsychotic monotherapy is recognized as the treatment of choice for patients with schizophrenia. Surveys have shown that antipsychotic polypharmacy are frequently prescribed, yet few randomized, double-blind clinical trials have examined this practice. Olanzapine, an atypical antipsychotic agent, has low incidence of extrapyramidal symptom but with high cost compared to trifluoperazine. It has been reported that mean doses of typical antipsychotics less than 600 mg per day of chlorpromazine or its equivalent has no higher risk of extrapyramidal symptom than atypical antipsychotics. The objective of the study is to compare the efficacy and safety of the olanzapine (10 mg per day) and olanzapine (5 mg per day) plus trifluoperazine (5 mg per day) in the treatment of acute psychotic exacerbations of schizophrenia. In this 6-week, double-blind, fixed-dose study, patients with schizophrenia are randomly assigned to olanzapine (10 mg per day)) or olanzapine (5 mg per day) plus trifluoperazine (5 mg per day). The hypothesis is that the two treatment groups have the similar efficacy and safety, but different cost. The primary efficacy measure is change from baseline in Positive and Negative Syndrome Scale (PANSS) total scores; secondary outcomes include Clinical Global Impression-Severity (CGI-S), the Calgary Depression Scale for Schizophrenia (CDSS), Global Assessment of Functioning Scale (GAF), Short Form-36 (SF-36), Mini Mental State Examination (MMSE). Safety assessments include the change from baseline on Simpson-Angus Rating Scale (SAS), Abnormal Involuntary Movement Scale (AIMS), Barnes Akathisia Scale (BAS), and UKU Side-effects Rating Scale, and the change from baseline in prolactin levels, body weight, vital sign, blood pressure, Bazett's correction of QT interval (QTc interval), fasting glucose level, and lipid panel (cholesterol, high density lipid protein, low density lipid protein, and triglyceride).

Inclusion Criteria:

• were physically healthy and had all laboratory parameters within normal limits
• were aged 18 to 55 years
• satisfied the DSM-IV criteria for schizophrenia
• had baseline Clinical Global Impression-Severity of Illness (CGI-S) scale score of 4 or greater
• had no DSM-IV diagnosis of substance abuse or dependence (including alcohol)
• had not received depot antipsychotic drugs for the preceding 3 months
• gave written informed consent to participate in the study after a full explanation of the study's aims and procedures.

Exclusion Criteria:

• those with a history of serious adverse reaction to olanzapine or trifluoperazine or a history of tardive dyskinesia or neuroleptic malignant syndrome
• female subjects who were pregnant or at risk for pregnancy or lactation
• those that had a diagnosis of treatment-resistant schizophrenia or having previously received clozapine or electroconvulsive therapy