Pfizer’s pill Chantix carries by far the greatest risk of leading to suicidal behavior or depression of any drug to quit smoking available to U.S. consumers, according to a new study published online in the journal PLoS One.

That finding counters recent research by the Department of Veterans Affairs and by the Department of Defense. The government research, which tracked patients in 2006 and 2007, found that Chantix is no more likely to cause psychiatric problems leading to hospitalization than nicotine replacement therapies such as NicoDerm patches.

But Dr. Curt Furberg, a professor of public health sciences at Wake Forest Baptist Medical Center and a co-author of the new PLoS One study, said Chantix’s track record demonstrates that, “The risks simply outweigh the benefits.”

As ABC News reports, his study urges the FDA to update Chantix’s warning label to indicate that the psychological risks of the drug exceed those of nicotine replacement drugs and Chantix’s direct competitor, Zyban. That would ratchet up the advisory about Chantix, which along with Zyban already carries a “black box” alert — the FDA’s most serious warning — cautioning doctors and patients about the risk of depression, hostility and suicidal thoughts.

As FairWarning reported in December, the controversy over Chantix’s side effects, particularly for smokers with mental health issues, has triggered a torrent of lawsuits. Reportedly, more than 1,500 cases have been filed in federal court. Many of the plaintiffs claim the drug led to suicides or suicide attempts, or other problems such as psychosis, blackouts and aggression.

FairWarning pointed out that Pfizer failed, in years of clinical trials, to test the drug on mentally ill smokers — despite the fact that a disproportionate number of smokers suffer from psychiatric illness and are a key part of the target market for smoking cessation treatments.

The PLoS One study, which relies on data from the U.S. Food and Drug Administration, analyzed 3,249 reports of serious self-injury or depression from 1998 through September 2010 linked to Chantix, GlaxoSmithKline’s Zyban or nicotine replacement products.

Researchers found that 2,925 cases, or about 90 percent, of the suicidal behavior or depression reported to the FDA was related to Chantix, even though the drug was approved for the marketplace relatively recently, in 2006, as Reuters reports.

By comparison, there were 229 cases of suicidal behavior or depression linked to Zyban and 95 cases related to nicotine replacement products.

Furberg, whose research team included scientists from Harvard and Johns Hopkins University, said he is skeptical of the recent government studies downplaying Chantix’s risks.

He said they “were flawed because they could not capture most of the serious psychiatric side effects, including suicide, depression, aggression and assaults. These can be catastrophic events but do not normally result in hospitalization,” Furberg said in a statement.

Pfizer, for its part, faulted Furberg for publishing analyses based on a review of spontaneous reports. It said, in a statement, that such reports “do not establish a cause and effect relationship between a medicine and a reported adverse event.”

The company is conducting its own large-scale study of Chantix’s behavioral effects but results won’t be available until 2017.

Separately, according to THV, a local television station in Little Rock, the Arkansas Psychiatric Clinic is one of several clinics across the country working on a Pfizer-sponsored trial to help adolescents ages 12 to 19 quit smoking. Participants, most of whom will need parental permission to participate, will be given either a placebo or Chantix over 12 weeks, along with counseling sessions. Patients will then be followed for approximately nine more months.


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