July 25, 2011 (Rockville, Maryland) — The Food and Drug Administration (FDA) has updated the label for varenicline (Chantix, Pfizer) to include new safety and efficacy information about the smoking-cessation medication [1].

Specifically, the label warns physicians that while varenicline is effective in helping patients with cardiovascular disease quit smoking, it is also associated with a small increased risk of cardiovascular adverse events in this patient population. The risks were first communicated in a July 16, 2011 drug safety communication, reported by heartwire , which stated that physicians need to balance the known benefits of varenicline--a drug effective in helping patients quit smoking--with the potential risks when deciding to use the drug in patients with cardiovascular disease.

As reported previously, the new label is the result of a review of a randomized, double-blind, placebo-controlled study of 700 patients treated with varenicline for smoking cessation. In this analysis, which was not powered to detect statistical differences in clinical end points, there was a numerically higher risk of nonfatal MI, revascularization, angina pectoris, and peripheral vascular disease in patients taking varenicline compared with patients treated with placebo.

Last week, Dr Sonal Singh (Johns Hopkins University School of Medicine, Baltimore, MD), Dr Curt Furberg (Wake Forest Baptist Medical Center, Winston-Salem, NC), and colleagues published a meta-analysis in CMAJ showing that varenicline was associated with a significantly increased risk of serious adverse cardiovascular events compared with placebo.

In addition to updating the safety warning, the FDA provided information on the use of varenicline in patients with chronic obstructive pulmonary disease (COPD). In a study of 460 patients with COPD, varenicline was more effective than placebo in getting patients to quit smoking but was not associated with any increased risk of adverse events.

The updated label also states that patients should start taking varenicline seven days before their smoking quit date or to begin the drug and then quit smoking between day 8 and day 35 of treatment.

In Europe, the European Medicines Agency (EMA) is telling prescribers that it believes the benefit/risk balance for varenicline "remains positive" [2], adding that the agency found a number of limitations in the Singh and Furberg meta-analysis, the most striking of which was the low number of overall events. The agency's Committee for Medicinal Products for Human Use (CHMP), however, has asked Pfizer to submit additional information on cardiovascular events that could be added to the product information.

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