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Clozapine Linked with Metabolic Syndrome

July 7, 2006

Antipsychotic drug clozapine has been linked with metabolic syndrome, according to a new study. Metabolic syndrome is a cluster of conditions that includes obesity, high blood sugar, high blood pressure and high cholesterol and can lead to diabetes, heart disease and stroke.

Steven Lamberti, MD, and colleagues at the University of Rochester Medical Center published their study results in the American Journal of Psychiatry, recommend that doctors check for metabolic syndrome in people taking clozapine.

Clozapine is marketed in the US under the brand-names Clozaril and Fazaclo.

Clinical Trial

Dr Lamberti and colleagues studied 93 people with schizophrenia who were taking clozapine, comparing some of their health parameters with those of 2,700 people from a health database who were of a similar age, weight and ethnicity.

Results showed that, while over 50% of the people taking clozapine had metabolic syndrome, only about 20% of those in the control group had the syndrome.

The increased risk of metabolic syndrome in people taking clozapine poses a dilemma for doctors and their patients, said Dr Lamberti, particularly because, for the approximately 20% of patients who do not respond to other anti-psychotic medications, clozapine may be their last hope.

“[Whether or not to prescribe clozapine] is a very difficult decision,” Dr Lamberti said. “On the one hand, we know that metabolic syndrome is associated with increased morbidity and mortality. We think that patients with metabolic syndrome have a two- or three-fold increased risk of cardiovascular disease. And the prevalence of metabolic syndrome in patients taking clozapine was over twice what it should be.

"On the other hand, patients who have schizophrenia that require clozapine do not respond to other medications and in the absence of this treatment are faced with the possibility of a life of active psychosis."

Other Contributing Factors

Other factors besides clozapine itself may contribute to metabolic syndrome in people with schizophrenia, Dr Lamberti noted. For example, people with schizophrenia are known to exercise less and have poorer diets – factors that may significantly contribute to metabolic syndrome.

Also, people with schizophrenia who are taking no medication for this condition have also been shown to have a higher risk for diabetes, for reasons as yet unknown: "We do not know why. There are a number of theories. It might be that what ever is affecting the brain in schizophrenia is also affecting the metabolic system."

Dr Lamberti also noted that newer, atypical antipsychotic medications, including clozapine, have been shown to offer advantages over older medications for schizophrenia in safety and effectiveness.

Paul Corry, of Rethink (formerly the Schizophrenia Fellowship) in the United Kingdom, welcomed the call for health care practitioners to closely monitor the side effects of drugs prescribed for mental illness:

"People with severe mental illness die, on average 10 years younger because of physical health problems and are five times more likely to experience diabetes than the general population,” he said.

"It is crucial that the physical health needs of people with severe mental illness are taken seriously."

Posted: July 2006