A new study says a smoking cessation drug manufactured by the pharmaceutical giant Pfizer Inc. is the prescription medication most often linked in the U.S. to violent acts or violent thoughts toward others.

The study, published Wednesday in the journal PLoS ONE , reviewed drugs most often linked to violent thoughts or actual violent acts, such as physical assaults, in reports received by the Food and Drug Administration. It covered a five-year period ending in 2009.

The Pfizer medication Chantix, generically known as varenicline, led the way with 408 reports related to violence.

As FairWarning has reported, Chantix has been associated with serious adverse events, including suicides and attempted suicides and is the subject of about 1,000 lawsuits. But Thomas J. Moore, lead author of the study and a scientist with the the nonprofit Institute for Safe Medication Practices in Horsham, Pa., argues that more attention needs to be paid to the drug’s potential to induce violence.

Second on the list, after Chantix, was the antidepressant Paroxetine, also known as Aropax, Paxil and Seroxat. It drew 177 reports of violent thoughts or actions.

Among smoking cessation aids, Zyban, also known as bupropion, followed Pfizer, with 35 incidents.

Michael Cummings, a smoking cessation expert at the Roswell Park Cancer Institute in Buffalo, N.Y., who was not involved in the study, questioned the validity of the results. He said the reports reviewed by the researchers are “probably not good enough” by themselves to draw a strong conclusion.

Pfizer, for its part, said “there is no reliable scientific evidence that Chantix causes violent thoughts or actions.”

Among the other drugs associated with violence were medications for attention deficit disorder and sedatives. Moore was joined in the study by researchers from the Harvard University and Wake Forest University medical schools.

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