NEW YORK, August 3 (Praxis Press) The antipsychotic drug, Mellaril (thioridazine) has been shown to prolong patients' QTc interval, which can lead to a type of ventricular tachycardia known as torsades de pointes and potentially sudden death. At the request of the US Food and Drug administration (FDA), the manufacturer of the drug, Novartis, has now added a black box warning on the drug's label in order to alert physicians to its tendency of prolonging a patient's heartbeat interval. Now Mellaril is indicated only for patients with schizophrenia who either cannot tolerate other antipsychotic drugs or who fail to respond to them.