FDA expands Chantix warnings to include increased heart risks
August 1st, 2011 by Kurt Niland
The black-box warning on Pfizer’s smoking-cessation drug Chantix (varenicline) just got bigger, following the results of a new study that found the drug caused an increased risk of heart attack and other adverse cardiac events in some patients. According to the U.S. Food and Drug Administration, the warning on Chantix labeling will include information about the safety and effectiveness of the drug in patients with existing cardiovascular disease and those with chronic obstructive pulmonary disease (COPD).
The FDA issued a new Chantix warning in June, alerting health care professionals and patients to the results of a new randomized, double-blind clinical trial of 700 smokers who were given either Chantix or a placebo. All of the participants had been diagnosed previously with heart disease. After 12 weeks on Chantix, researchers found that more than twice as many Chantix patients suffered heart-related problems than the placebo patients.
The events included angina pectoris, nonfatal myocardial infarction, the need for coronary revascularization, and new diagnosis of peripheral vascular disease or admission for a procedure for the treatment of peripheral vascular disease. Seven out of 353 Chantix patients had a nonfatal heart attack, versus 3 out of 350 of the placebo patients.
The new label warning also includes information about the potential effects of Chantix on COPD patients. This information is based on findings from a clinical trial of 460 patients with mild to moderate COPD who were randomly given either Chantix or placebo for 12 weeks and then monitored for 40 weeks.
According to the FDA, the adverse events reported in this trial underscored some of those that were found in studies conducted for Chantix’s initial approval in 2006, but no new concerns were identified.
It should be noted that the new required warnings do not reflect the results of a larger, more recent study that monitored the cardiovascular health of 8,000 Chantix patients in a series of 14 smaller clinical trials. The New York Times reported the results of this study, which was published in the Canadian Medical Association Journal. It revealed that 52 smokers in the Chantix groups suffered a heart attack, stroke, or other serious cardiovascular event while just 27 smokers taking placebo experienced the same cardiovascular problems.
In the real world, this means that “doctors could expect to get one extra cardiac event associated with Chantix for every 28 smokers they treated with the drug,” the New York Times reported.
Despite the new warnings and mounting evidence that the dangers of Chantix have been greatly understated, the FDA continues to allow the drug a place on the market. According to the agency, “Smoking is an independent and major risk factor for cardiovascular disease, and smoking cessation is of particular importance in this patient population. The known benefits of Chantix should be weighed against its potential risks when deciding to use the drug in smokers with cardiovascular disease.”
Additional sources:
http://www.ismp.org/quarterwatch/2010Q2.pdf
http://www.medpagetoday.com/PrimaryCare/Smoking/27711