Pfizer's smoking-cessation drug Chantix (varenicline) is not suitable for first-line use due to its poor safety profile, contradicting a recent FDA review, according to a study appearing in the journal PLoS One.
Researchers from the Wake Forest Baptist Medical Center, the Institute for Safe Medication Practices, Harvard Medical School and Johns Hopkins University School of Medicine say Chantix, which carries a black-box warning, has demonstrated a substantially increased risk of reported depression or suicidal behavior versus other smoking-cessation treatments. In fact, 90% of all reported suicides related to smoking-cessation drugs since 1998 have implicated Chantix, even though it was on the market only four years in the nearly 13-year study period.
The researchers looked at 3,249 case reports of serious injury from 1998 through September 2010 linked to Chantix, the antidepressant Zyban (bupropion), which is also approved for smoking cessation, and nicotine replacement products. They identified 2,925 cases of suicidal behavior or depression for Chantix, 229 for Zyban, and 95 for nicotine-replacement products.
The FDA recently said that after reviewing two studies comparing Chantix with standard nicotine-replacement therapy, those persons on the Pfizer drug were no more likely to be hospitalized for psychiatric complaints than the nicotine-patch patients were.
"Our study contradicts the implications of a recent review by the FDA showing no difference in psychiatric hospitalizations between varenicline and nicotine-replacement patches," said study co-author Curt Furberg, professor of Public Health Sciences at Wake Forest Baptist. "The FDA hospitalization studies 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."
Chantix also is associated with other side effects, including cardiovascular events, aggression and problems with vision, cognition and motor control, the authors say. They urge the FDA to revise Chantix's black box warning to say the drug has higher risks for suicidal behavior and depression when compared with other stop-smoking treatments. Furthermore, Chantix should only be used after other smoking-cessation treatments fail, they add.
An FDA spokeswoman responded to the study, saying the drug is a safe and effective way to help smokers quit. She also pointed out that the study didn't account for the rise in reports of psychological side effects from Chantix after increased media coverage of the drug since 2007, ABC News reports.
Pfizer also fought back, taking issue with the researchers' data. "The analysis by Moore et al is based solely on post-marketing reports of adverse events that have been available to the FDA for some time," the drug giant says in a statement. "Post-marketing reports do not establish a cause and effect relationship between a medicine and a reported adverse event. These reports can come from any source ranging from patients to healthcare providers, and from phone calls to Internet postings. Often these reports lack sufficient medical information to enable a meaningful assessment."
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