Prescription Smoking Cessation Drug Chantix More Trouble Than it's Worth?
Chantix, also known as Varenicline (var en' i kleen), is a prescription grade smoking cessation tablet that is intended to be taken orally once or twice a day with a full glass of water and food. Chantix is typically prescribed for a 12-week period, at the end of which, it is anticipated that many people will cease smoking. It has been on the market for about 5 years and became the best-selling drug of its type, both in the United States and overseas, until recent negative publicity began to detract from its success.
Formerly, the side effects associated with Chantix, as listed by the National Center for Biotechnology Information (a division of the National Library of Medicine at the National Institutes of Health) were nausea, constipation, gas, vomiting, heartburn, bad taste in the mouth, increased or decreased appetite, trouble falling asleep or staying asleep, unusual dreams or nightmares, drowsiness, and headache. The more serious side effects included swelling of the face, tongue, lips, gums, throat, arms, or legs, difficulty swallowing or breathing, rash, swollen, red, peeling or blistering skin, and blisters in the mouth. Other sources reported risks such as loss of consciousness, visual disturbances, suicides, violence, depression, and worsening of diabetes.
Recently, a randomized, double-blind, placebo-controlled clinical trial that included 700 smokers with cardiovascular disease who were treated with Chantix or a placebo indicated a link between Chantix and adverse cardiovascular events. The cardiovascular events included angina pectoris, nonfatal myocardial infarction, need for coronary revascularization, and new diagnosis of peripheral vascular disease or admission for a procedure for the treatment of peripheral vascular disease. These warning are now being added to the Warnings and Precautions section and the patient Medication Guide.
An even newer study, published in a Canadian medical journal, showed a link between Chantix and an increased risk of heart attack, stroke, and other serious cardiovascular events for smokers without a history of heart disease compared to smokers who did not use the drug. This new study analyzed 14 randomized clinical trials which involved 8,200 patients and completely excluded those with cardiovascular disease. The study revealed an absolute difference of 0.24 percent and a relative different of 72% in serious cardiovascular outcomes between people who took Chantix compared with people who were taking a placebo. When assessing the studies of smokers with and without pre-existing disease, Chantix was associated with 1 extra cardiac event for every 28 smokers treated. One more person quit for every 10 who took Chantix.
Chantix's manufacturer, Pfizer, and the FDA reported plans to conduct a joint analysis of clinical trials on cardiovascular events, but it was not slated to be performed until next year.
How do these drugs become approved? The company that desires to market a drug must test it and submit evidence that it is safe and effective to the FDA. The FDA has five major centers, which are responsible for ensuring the safety of over the counter and prescription drugs, medical and radiological devices, food, cosmetics, biologics, and veterinary drugs. Although the FDA's Center for Drug Evaluation and Research (CDER) does not test drugs, the FDA Office of Testing and Research does conduct related limited research (developing new scientific methods and regulatory testing, providing scientific support, providing scientific training, and so on). The CDER's physicians, statisticians, chemists, pharmacologists, and other scientists review the drug sponsor's new drug application (NDA), which contains its research data and proposed labeling. In order to protect and promote public health, the FDA may order additional clinical trials (Phase IV trials), clinical holds, and risk management plans.
Resources:
The New York Times, Study Links Smoking Drug to Cardiovascular Problems, Duff Wilson, 07.04.2011.
Similar Blog Posts:
Wall Street Journal Blogs, A.M. Vitals: Research Review Links Pfizer's Chantix to Heart Problems, Katherine Hobson, 07.05.2011.
By Kathleen Beatty
