Delirium occur frequently in hospitalized patients. High-potency antipsychotic drugs have been used for the treatment of delirium; however, there is a risk of acute side effects. Therefore, atypical antipsychotic drugs could be used to the treatment of delirium.

The present study aimed to provide comparison of intramuscular injection of olanzapine and intramuscular injection of haloperidol for patients with delirium was conducted with a randomized, open prospective study.

Sixty-two patients admitted at the Catholic University of Korea Kangnam St. Mary's hospital, Seoul, South Korea were enrolled in this study. They were diagnosed as delirium by two independent psychiatrists using DSM-IV-TR. the Delirium Rating Scale-revised-98(DRS-R-98) and clinical global impression-severity (CGI-S) were checked daily. the Simpson-Angus Rating Scale, the Barnes Akathisia Rating Scale and the Abnormal Involuntary Movement Scale were used for the assessment of side effects.

The DRS-R-98 and CGI-S scores were significantly decreased over time in both treatment groups without any significant group difference and time by the group interaction effect (F=28.35, P< 0.0001). Adverse events occurred lower in olanzapine group. both treatments were well tolerated and there were no serious adverse events occurred by intramuscular olanzapine or haloperidol.

This study showed that either intramuscular olanzapine or intramuscular haloperidol would be effective and tolerable for treating delirium, however, olanzapine showed lower side effects than haloperidol. Adequately powered studies will be mandatory to draw any definite conclusion.