Quetiapine Therapy in Treatment-Refractory Schizophrenia

Objective: We investigated the effects of an atypical antipsychotic agent, quetiapine, in treatment-refractory schizophrenia. Methods: The subjects were 10 inpatients who were diagnosed according to the DSM-IV criteria for schizophrenia. They were termed treatment refractory. We tried to switch patients from typical antipsychotics to quetiapine. Each patient gave informed consent for the research involved in this study. The assessment of psychotic symptoms was done before and after replacement by quetiapine administration using the Brief Psychiatric Rating Scale (BPRS). Plasma homovanillic acid (pHVA) level was also assessed. Patients took a mean dose of 602.5 mg quetiapine daily for a mean period of 100.9 days. Results: (i) Although the total BPRS score did not show significant changes, three out of 10 patients (30%) showed improvement by BPRS criterion. (ii) The pHVA levels did not show significant difference between blood levels before and after replacement by quetiapine administration. (iii) There was a positive correlation between the pHVA levels at baseline and total BPRS scores. (iv) pHVA changes between baseline and quetiapine steady state (∆pHVA) were correlated positively with BPRS changes (∆BPRS). Conclusions: Quetiapine has a greater affinity for 5-hydroxytryptamine-2 receptors than dopamine D2 receptors. Our results indicated that typical antipsychotic replacement by quetiapine might be effective for some treatment-refractory schizophrenic patients, and changes in pHVA were correlated with the therapeutic response to quetiapine (German J Psychiatry 2001;4:63-67).