Pfizer's Chantix increases risk of cardiovascular adverse events: analysis

An analysis published Monday in the Canadian Medical Association Journal suggests that Pfizer's smoking cessation drug Chantix (varenicline) is associated with a 72-percent higher risk of serious cardiovascular adverse events compared to placebo. "I think our new research shifts the risk-benefit profile" of the product, commented lead study author Sonal Singh.

The meta-analysis included 8216 patients enrolled in 14 clinical trials, 13 of which excluded people with a history of heart disease, with each study having a duration of seven to 52 weeks. Results showed that of the 4908 people who took Chantix, 52 experienced serious cardiovascular adverse events such as heart attack or arrhythmia, compared with 27 of the 3308 people who received placebo. Singh noted that the risk of complications linked to Chantix doubled for patients with no history of heart disease, although he said it's unclear whether the added heart risk persists after treatment ends.

Gail Cawkwell, Pfizer's vice president for medical affairs, said the drugmaker "disagrees with the interpretation of the data," adding that "about one in 100 people in the studies had cardiovascular problems." The company said the analysis was based on too few heart or cardiovascular events to draw conclusions about the risks.

Last month, US regulators said Chantix was associated with a slightly higher chance of cardiovascular adverse events in patients who have cardiovascular disease, and it also has previously been linked with an increased risk of serious mental health events.

Commenting on the new analysis, Curtis Rosenbraugh, director of the FDA's office of drug evaluation, said the agency is examining the data. "I'm not sure until we can further evaluate the study whether it’s going to change the label or not, but I can assure you this is something we’re very concerned about and are taking very seriously," Rosenbraugh remarked.

In an accompanying commentary in the journal, J. Taylor Hays called the analysis "timely and important" but said it lacked overall size and standardisation. “The risk for serious cardiovascular adverse events is low and is greatly outweighed by the benefits of diminishing the truly heartbreaking effects of smoking," he suggested.

Sales of Chantix have fallen by more than 10 percent since 2008, and reached $755 million last year.

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