Newer anti-psychotic medications used to treat schizophrenia, dementia and other psychiatric disorders appear to double a patient's risk of sudden heart failure, research published Thursday in the New England Journal of Medicine found.
The major study is the latest in recent months to show that these newer drugs, dubbed "atypical medications," are not much safer than the older generation of "typical" treatments, as scientists had widely thought.
"Although a link between the use of typical anti-psychotic drugs and both torsades de pointes (a form of heart disorder) and sudden cardiac death has been established, this risk was thought to be lower with the use of atypical drugs," the authors wrote.
They said that now "limited data available" suggest the "electrophysiological effects" of both types of drugs are similar.
The new generation of drugs examined in the study, which also are significantly more expensive than their predecessors, include Johnson and Johnson's Risperdal; AstraZeneca's Seroqueland Eli Lilly's Zyprexa.
The three drugs are among the top sellers in their class with more than 14.5 billion dollars in sales worldwide in 2007.
Some doctors have warned against these drugs being prescribed "off-label" or for conditions not approved by the US Food and Drug Administration (FDA).
That includes Alzheimer's and hyperactivity in young people.
"Current users of typical antipsychotic drugs and of atypical antipsychotic drugs in the study cohort had a similar dose-related increased risk of sudden cardiac death," said the authors of the study led by Dr Wayne Ray of Vanderbilt University Medical School in Tennessee.
"This finding suggests that with regard to this adverse effect, the atypical antipsychotic drugs are no safer than the older drugs."