Objective: The purpose in producing and utilizing new  antipsychotic agents has been to achieve relatively more effective and safe treatments. Conducted in two sites in Turkey, the aim of this study was to compare the efficacy and safety profiles of olanzapine and chlorpromazine in a 6-week acute treatment phase.

Method: Patients included in the study were 18-55 years of age with a diagnosis of schizophrenia according to the DSM IV criteria.  In a 2:1 ratio, 20 patients were given olanzapine and 10 patients were given chlorpromazine in a random design.  The Positive and Negative Syndrome Scale (PANSS),  the Brief Psychiatric Rating Scale (BPRS) extracted from PANSS, and the Clinical Global Impression-Severity Scale (CGI-S) were utilized in assessing the severity of illness, and the UKU Side Effect Rating Scale and the Extrapyramidal Symptom Rating Scale in assessing the safety. Statistical analysis of outcome was performed on the findings of 27 patients who completed the assessments. 

Results: The efficacy findings showed that both treatment groups exhibited statistically significant and comparable improvements in all symptom groups. Safety findings showed that chlorpromazine caused a tendency for orthostatic hypotension and statistically significant higher severity of fatigue. Olanzapine caused a tendency for elevation of the liver transaminases and statistically significant higher severity of emotional indifference and polyuria.  Weight gain was evident in both treatment groups without a statistically significant difference. Other than the significant increase in parkinsonian symptoms in the first weeks of chlorpromazine treatment, the extrapyramidal side effect profiles of both drugs were found to be favorable. 

Conclusion: Chlorpromazine is a drug which should keep its place as a major agent in antipsychotic treatment;  olanzapine, with its favorable side effect profile, is a promising agent for the modern era of antipsychotic treatment, being at least as effective as the older agents.