Report highlights adverse events for Chantix

A report by a US non-profit organisation suggested that Pfizer's smoking cessation product Chantix (varenicline) has been linked to more than 3000 reports of adverse events including suicides, cardiovascular problems, diabetes and seizures.

The Institute for Safe Medication Practices reviewed adverse event reports submitted to the FDA. The data showed that 988 serious injuries in those taking the drug were reported in the fourth quarter of 2007, more than any other product available on the market. "These data provide a strong signal that the risks of varenicline treatment have been underestimated, and show that a wide spectrum of serious injuries are being reported in large numbers," the authors stated.

The report concluded that Chantix should not be used in those operating airplanes, cars or other machinery because of the potential for seizures, hallucinations or loss of consciousness. The organisation also specified that more information is needed to determine whether the drug is responsible for the adverse events, and called on the FDA and Pfizer to investigate the potential risks of the compound.

In response, Pfizer said that "the current Chantix label accurately reflects the product's efficacy and safety profile." An FDA spokesperson commented that the study highlights safety signals about the product, but noted that due to a lack of resources, the agency is currently focusing on reviewing psychiatric adverse events potentially associated with Chantix. Meanwhile, the Federal Aviation Administration announced that pilots and air traffic controllers were banned from using the drug.

In February, the FDA issued an advisory stating that a link between Chantix and serious neuropsychiatric symptoms appears “increasingly likely."

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