Stop smoking drug linked to heart risk

5^th July 2011 - Smokers who take a commonly prescribed drug to help them quit the habit may be putting themselves at an increased risk of heart attacks and other cardiovascular problems, according to a new study.

Researchers from the University of East Anglia (UEA) and two US universities investigated the cardiovascular effects of varenicline, known by its brand name Champix. "We analysed 14 clinical trials involving more than 8,200 otherwise healthy smokers and the likelihood of developing serious cardiovascular events resulting in hospitalisation, disability or death was almost 72% higher in patients using varenicline,” said joint lead author Dr Yoon Loke of Norwich Medical School at UEA in a statement.

"Action needs to be taken by the company," said co-author Dr Sonal Singh, assistant professor of medicine, Johns Hopkins University, in the US, referring to Pfizer, the maker of Champix. "They need to put accurate safety information on the label," he tells us.

Pfizer said they disagreed with the way the data had been interpreted in the study.

Heart attacks, heart failure, stroke

In their analysis of data from 14 studies, the researchers found that 52 out of the 4,908 men and women taking varenicline experienced a serious cardiovascular event, such as heart attack, abnormal heart rhythm, stroke, heart failure, or related death, compared to 27 out of the 3,308 among those taking a placebo medication. That led the authors to conclude that varenicline raised the risk of serious cardiovascular problems by nearly 72% compared to placebo.

"Our findings have potential regulatory and clinical implications," the researchers conclude, writing in the Canadian Medical Association Journal (CMAJ).

'Analysis limited': Drug manufacturer

Pfizer emailed us a statement saying it strongly believed in and supported the medication as an important treatment option. It continued: "The analysis contains several limitations; most notably that it is based on a small number of events, which raises concerns about the reliability of the authors' conclusions. The authors acknowledge that their risk 'estimates are imprecise owing to the low event rates'.

"The actual difference in cardiovascular event rates seen in the Singh analysis was less than one quarter of one percent (i.e., 1.06% with varenicline versus 0.82% with placebo).

"The health benefits of quitting smoking are immediate and substantial. Smoking is a major risk factor for cardiovascular disease, which can lead to heart attack, stroke and peripheral arterial disease.  Each year, an estimated 5.4 million people worldwide die from smoking related causes."

Pfizer said it was working with regulators to evaluate the cardiovascular safety of varenicline.