Pharmaceutical company Pfizer’s drug to help smokers quit, which has already been linked to psychiatric side effects, can lead to a small increase in heart problems in those who have cardiovascular disease, US health regulators said on June 16.
The Food and Drug Administration (FDA) is changing the Chantix label to identify the increased heart risk after reviewing the results of a clinical trial. Chantix, usually in the form of varenicline tartrate, is a prescription medication used to treat smoking addiction.
Varenicline is a nicotinic receptor partial agonist. It is similar to Cytisine (a pyridine-like alkaloid which, in large doses, can interfere with respiration and become fatal) and different from nicotine replacement therapies like Bupropion (a typical antidepressant and smoking cessation aid) or nicotine patches and gum.
As a partial agonist, it both reduces cravings for and decreases the pleasurable effects of cigarettes and other tobacco products. Through these mechanisms, it can assist some patients to quit smoking.
The FDA requires Chantix to carry a black box warning, the agency’s strongest safety warning, due to public reports of side effects including depression, suicidal thoughts and suicidal actions.
An independent randomised trial of 700 smokers with cardiovascular disease who were treated with Chantix or a placebo showed that the Pfizer drug was effective in helping patients quit smoking for as long as one year. However, patients who took the pill were also slightly more likely to have a heart attack or other adverse cardiovascular problem compared with patients who received a placebo.
Many smokers who try to quit do so to prevent the risk of heart attacks, which may now be associated with Chantix. “The known benefits of Chantix should be weighed against its potential risks when deciding to use the drug in smokers with cardiovascular disease,” the FDA said in a statement. The FDA said it is also requiring Pfizer to evaluate the cardiovascular safety of Chantix by conducting a large, combined analysis of randomised, placebo-controlled trials.
Pfizer said in a statement that it would be discussing details of such an analysis as well as the product’s label with the FDA. The company said that in a Chantix clinical trial of smokers with certain types of heart disease reports of adverse cardiovascular problems were low.
Published in The Express Tribune, June 20th, 2011.