The drug clozapine is more effective than olanzapine or haloperidol at reducing aggressive behavior in violent patients with schizophrenia, new research shows. This ability to curb aggressiveness seems to be separate from the drug’s antipsychotic effect.

Schizophrenia is a severe psychiatric disorder in which patients experience distorted thinking, hallucinations and abnormal emotions. The disease is classified as a psychotic disorder, meaning that patients are often not completely in touch with reality. Therefore, the disease is treated with antipsychotic drugs, including the newer, “atypical” drugs clozapine and olanzapine as well as the older drug haloperidol.

“There had been evidence in the literature that the atypical antipsychotics have some specific anti-aggressive effects,” but a lot of the supporting data came from studies that didn’t focus on violent patients, lead author Dr. Menahem I. Krakowski, from the Nathan Kline Institute for Psychiatric Research in Orangeburg, New York, told Reuters Health.

The study, which is reported in the Archives of General Psychiatry, involved 110 patients at state psychiatric facilities who were randomly selected to receive clozapine, olanzapine or haloperidol for 12 weeks.

To be eligible for the study, the subjects had to have a documented episode of physically assaulting another person while hospitalized and display persistence of their aggression in the form of other aggressive events.

In terms of reducing both overall and physical aggression, clozapine was significantly better than olanzapine, which, in turn, was significantly better than haloperidol. By contrast, the agents were comparable in their ability to improve psychiatric symptoms.

“Clozapine was better than the other drugs at reducing physical assaults, threats, and insults and in preventing patients from destroying property and throwing objects,” Krakowski said.

While clozapine is the most effective drug, Krakowski warned that the drug also has some important side effects and regular blood monitoring is critical. For this reason, olanzapine might be a better initial choice, he added, unless the patient has hard-to-control aggressive behavior.

SOURCE: Archives of General Psychiatry, June 2006.