- Quetiapine, a drug with a broad pharmacologic profile (similar to that of clozapine), may show benefits for agitation in patients with psychoses. Also, quetiapine may be superior to placebo and either equal or superior to haloperidol in treating this symptom. Available data for other second-generation antipsychotic agents show that quetiapine may have better efficacy in improving agitation compared with haloperidol. This reanalysis of a previously reported pivotal clinical trial assessed whether quetiapine or haloperidol has benefits for the treatment of hostility and agitation among patients experiencing an acute exacerbation of schizophrenia. Patients aged 18 to 65 years of either sex and any ethnicity who had a diagnosis of schizophrenia based on the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition criteria and who were experiencing an acute exacerbation were recruited into the study. A priori, data from patients assigned to 4 therapeutically effective quetiapine treatment groups (150, 300, 600, and 750 mg) in a previously reported 6-week, double-blind, placebo-controlled clinical trial were combined and compared with data from patients given haloperidol 12 mg or placebo on an agitation measure derived from the Brief Psychiatric Rating Scale (BPRS). Patients who received at least 2 weeks of treatment who had a baseline assessment and at least 1 postbaseline assessment after the 2 weeks of treatment were included. An analysis of variance with the baseline hostility score and center as covariates was used to assess treatment effects of quetiapine or haloperidol versus placebo for changes in agitation scores. A path analysis was used to separate the direct from the indirect effects (via improvements in psychoses and/or overall psychopathology) on agitation scores of quetiapine relative to haloperidol. A total of 257 patients (193 men, 64 women) were studied. The combined quetiapine groups comprised 175 patients; the haloperidol group, 42 patients; and the placebo group, 40 patients. Quetiapine treatment reduced agitation scores significantly among patients with acute psychoses compared with placebo. A slight reduction in agitation scores was found when haloperidol treatment was compared with placebo, but this difference was not statistically significant. Compared with haloperidol, quetiapine treatment had a direct and significant effect on agitation that was independent of the improvement in psychotic symptoms. The data in this study suggest that quetiapine treatment has benefits for hostility and agitation among patients experiencing an acute exacerbation of schizophrenia. Furthermore, the path analysis indicated that, relative to haloperidol, quetiapine appeared to have direct effects on agitation that were independent of improvements in psychoses or overall psychopathology, as assessed by the BPRS.