Quit-smoking drug linked to increased risk of heart attack

A stop-smoking pill used by thousands of Britons increases the risk of heart attacks and stroke by more than 72 per cent, new research suggests.

In the United States, the drug now carries a warning of an increased possibility of problems when used by smokers who already have heart disease.

Champix (varenicline) is a prescription-only medicine and accounted for 955,242 prescriptions in England in 2010.

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The drug works by cutting the cravings experienced by smokers, but has raised fears in the past after patients using it reported depression, suicidal thoughts and anxiety.

Now a team of researchers has linked the drug, which is one of the most commonly used drugs prescribed to help people stop smoking worldwide, to an increased risk of being admitted to hospital with a serious cardiac event such as a heart attack.

The study, published in the Canadian Medical Association Journal, analysed data recorded for more than 8,000 people involved in 14 medical separate trials.

Taking the drug was associated with a “significantly increased risk of serious adverse cardiovascular events”, such as heart attack and stroke, when compared with placebo, it was found.

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Dr Sonal Singh, from the Johns Hopkins University School of Medicine in Maryland in the US, who worked on the study, said: “Among tobacco users, varenicline use was associated with a significantly increased risk of serious adverse cardiovascular events greater than 72 per cent.”

A total of 52 of 4,908 people on the drug had adverse events compared with 27 of 3,308 people on placebo.

Despite that, researchers found there was no difference in death rates between the two groups, however.

The authors said the drug had helped people to quit, which should have a positive impact on the health of their heart.

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Yet those taking the drug had an increased risk of heart attacks and stroke and this was seen in people with and without heart disease.

Dr Singh said: “People want to quit smoking to reduce the risk of cardiovascular disease but in this case they’re taking a drug that increases the risk for the very problems they’re trying to avoid.”

In the US, regulators have recently updated labelling on the drug (which is called Chantix in the US) to say there is a small increased risk of cardiovascular events among smokers with heart disease.

In the UK, there have been hundreds of reports to regulators of changes in behaviour or thinking, including anxiety, psychosis, mood swings, aggressive behaviour, depression, suicidal thoughts and suicide attempts.

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The authors of the new research have highlighted limitations in their study, including variable data between the trials.

But they conclude: “Clinicians should carefully balance the risk of serious cardiovascular events and other serious neuropsychiatric adverse events associated with varenicline against their known benefits on smoking cessation.”

Dr Singh added: “People should be concerned.

“They don’t need Chantix to quit and this is another reason to consider avoiding Chantix altogether.”

One of the authors on the study, Dr Yoon Loke from the University of East Anglia, said: “Though the actual number of patients developing heart problems on varenicline is relatively low, these are life-threatening diseases and so any increased risk should be carefully avoided – particularly as heavy smokers are already susceptible to cardiovascular disease.”

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Dr Yoon went on: “In smokers who have a history of heart disease, we estimate that one in 28 of them would be troubled by additional heart problems if they used this drug for a year.

“Long-term trials are now needed to determine whether or not the overall health benefits of this drug outweigh the risks.”

She added: “In the meantime, I would advise people taking varenicline not to stop taking their medication suddenly, but to discuss any concerns with their doctor – particularly if they already have any heart-related health problems.”