And so, the debate over the cardiovascular risks of Chantix will likely continue. Why? A meta-analysis of clinical trials, which compared patients who received the Pfizer smoking-cessation drug to those given a placebo, yielded an inconclusive, but highly suggestive finding.
To wit, there was a higher occurrence of major adverse cardiovascular events - a combined outcome of cardiovascular-related death, nonfatal heart attack, and nonfatal stroke - in patients using Chantix compared to placebo, according to an FDA statement. These events were uncommon in both groups, but the increased risk was not statistically significant, which means it is uncertain whether the excess risk for the Chantix group was due to the drug or chance.
"However, the FDA adds, "the data were analyzed many different ways and consistently showed a higher occurrence of events in patients using Chantix, which makes it seem more likely that it is related to the drug and not purely a chance finding" (here is the statement and data summary).
The agency notes the findings are similar to what was seen in clinical trial patients with stable cardiovascular disease, which were described in an FDA safety communication in June 2011. At the time, the FDA added a warning on the product labeling about an association with a small, but increased risk of cardiovascular adverse events in patients with cardiovascular disease.
As we wrote then, the FDA reviewed a study in which 700 patients with cardiovascular disease received either Chantix or placebo, and the results showed the Pfizer drug was effective in helping them quit smoking and remain abstinent for up to year. But Chantix was also linked more frequently to “certain events, including heart attack” (here is the statement and data summary).
A month later, however, a meta-analysis published in the Canadian Medical Association Journal found that the Pfizer pill was associated with a 72 percent increased risk of serious adverse cardiovascular risks in smokers without a history of heart disease, and two authors suggested the FDA should consider having the drug removed from the market (back story).
This meta-analysis, however, prompted a controversy within a controversy as researchers at the University of California at San Francisco then conducted their own meta-analysis, which was published in BMJ and found Chantix does not increase the risk of heart attacks and strokes. They also criticized the methodology of the CMAJ analysis, sparking a heated war of words (read here).
Consequently, the latest FDA declaration is likely to add to the controversy over the drug, which has been associated with suicidal behavior and vivid dreams (see here and here). The government later banned Chantix for pilots and licenses wouldn’t be issued to truck drivers taking the med (see this and this).
The FDA subsequently imposed a risk management program and Pfizer (PFE) added warnings. Two years ago, a study in The Annals of Pharmacotherapy finds Chantix is associated with violent and aggressive thoughts and acts (read here). Another in PLoS One found an association with serious acts of violence, such as physical abuse, physical assault and homicide (look here).
cig smoke pic thx to jonaylor on flickr
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