Risperidone alone did not induce torsade de pointes: Experimental evidence from the chronic atrioventricular block model dogs

We assessed torsadogenic action of risperidone, which can potently inhibit IKr as well as α1-adrenoceptor. A toxic dose of 3 mg/kg of risperidone was intravenously administered over 10 min to chronic atrioventricular block dogs without anesthesia with monitoring Holter electrocardiogram (n = 4). Risperidone increased atrial/ventricular rate for 1–12 h/1–6 h and prolonged QTcF at 6 h after its administration, whereas it did not increase short-term variability of repolarization or induced torsade de pointes. These results suggest that α1-adrenoceptor blockade-dependent, hypotension-induced, reflex-mediated increase of sympathetic tone by risperidone might play a role in protecting the heart from IKr inhibition-associated torsade de pointes.