Heart concerns raised about anti-smoking medication, Champix?

Lung cancer is the second most common cancer among Canadian men and women and is the leading cause of cancer death. In 2010, some 25,400 Canadians will be diagnosed with lung cancer and 20,600 wil die with it.

We know that tobacco use is a major preventable cause of cancer and accounts for 85% of all new cases of lung cancer and also contributes to cancers of the larynx, oral cavity and pharynx, esophagus and bladder. It is also a major risk factor for heart disease, stroke and respiratory illness.

One smoking cessation aid is varenicline, marketed under the name Champix in Canada and Chantix in the U.S. Health Canada announced last week that it would review the safety of the drug.

heart concern

In this week’s CMAJ is a study reviewing the data to date on this medication and side effect profile. The authors looked at a total of 14 trials that all together included at 8216 patients of which 4908 were on the medication. All the studies except one excluded patients with heart disease.

In the study, 1.06% (52 of 4,908) on the medication had an adverse event compared to 0.82% (27 of 3308) on placebo. There were 7 deaths in the two groups. That means there were a greater percent dying in the placebo arm. In addition no study was performed greater than one year. The average age of participants was 45 and the majority of the participants were men.

The authors found a significant increase in serious adverse cardiovascular events greater than 72% in the treatment arm. The tobacco users on the medication however did have more than a twofold higher rate of abstinence in the trials.

Previous noted side effects on this medication include depression, agitation and suicidal thoughts which did result in a FDA black box warning previously.In June of this year the FDA did announce that on the basis of a 700-person study, people with existing heart disease who use the medication have a slightly higher risk of heart attack or other cardiovascular events

In the same journal, commentary by Dr. Hays of the Mayo Clinic agrees that the results “suggest a measure of caution should be taken” when prescribing the medication, however the absolute number of cardiovascular events in the treatment arm are small and he felt that the benefit of successful smoking abstinence and long term reduction in morbidity and mortality outweighs that small risk.

It should be noted that there is strong evidence to support the benefits of smoking cessation regardless of the age of quitting. The life time cumulative risk of death from lung cancer gets progressively lower as the time since cessation gets longer.

In 2011 some 25,200 men and women will develop lung cancer and 26,000 will die from the disease.