Study on the Influence of Second Generation Antipsychotics on QTc Interval Prolongation in Patients with Schizophrenia

Purpose: QTc interval prolongation is a focus of attention in application of antipsychotics as it may induce polymorphoric ventricular tachycardia, or torsade de pointes, and cause fatal risk. This study aims to investigate the influence of second generation antipsychotics on QTc interval prolongation for Taiwanese patients with schizophrenia. Method: A total of 64 schizophrenic patients without heart disease and stroke history were recruited and treated with second generation antipsychotics. An electrocardiogram examination was provided to them before and half year after the treatment respectively. The data were statistically evaluated using comparison of means and analysis of variances. Result: Average QTc of all of the patients after medication was 420ms, no more than 500ms. QTc of the patients prolonged in an average of 10.8ms and presented significant variances after they took the second generation antipsychotics. In terms of individual drugs, Quetiapine (13.3ms) and Clozapine (23.8ms) caused significant variances in QTc; but the remaining three drugs didn’t pose any notable variance. In comparison, Clozapine posed a remarkably greater effect on QTc than Risperidone and the remaining drugs didn't create any significant variance. Conclusion: Findings of this study indicated QTc intervals of all of the patients after medication were no more than 500ms; however some drugs still created significant influences on QTc. Clinically, physicians should be cautious in prescribing for schizophrenia patients with heart disease or using drugs that may affect QTc together with antipsychotics.