Stop-Smoking PIll Chantix May Cause Heart Attack, FDA Warns

(CBS/AP) A popular smoking-cessation drug may raise the risk of heart trouble, the FDA says.

The agency is warning doctors and patients that Chantix (varenicline) has been linked to heart-related chest pain (angina) and heart attack. The warning comes after a study of 700 heart patients taking Chantix showed a small uptick in heart problems like myocardial infarction and chest pain, compared to patients taking a placebo drug.

Chantix, which is made by Pfizer, is a twice-daily tablet that curbs symptoms of nicotine withdrawal by binding to nicotine receptors in the brain.

The FDA will add the new warnings to the drug's label, and patients will get updated medication guides along with their pills. Pfizer will be required to analyze a large group of studies to further define the heart risk, the FDA said.

The company downplayed the news, saying in a written statement that "the overall cardiovascular event rates reported in the study were low."

Chantix has been used by millions of patients in the U.S. since its approval in May 2006, though sales have declined since 2008, when the drug was linked to depression and suicidal thoughts. It carries the serious "boxed warning" about those risks.

GlaxoSmithKline's smoking-cessation drug, Zyban, carries the same warning.

The agency stressed, however, that Chantix helps patients quit smoking and that this benefit "should be weighed against its potential risks when deciding to use the drug in smokers with cardiovascular disease."