By Kate Kelland
LONDON (Reuters) â€“ Pfizerâ€™s stop-smoking drug Chantix does not raise risks of heart attack or depression, contrary to previous reports, and should be recommended to more smokers wanting to quit, scientists said on Monday.
In a study tracking 150,000 smokers in England for 6 months, researchers found that patients who took Chantix, known generically as varenicline and marketed as Champix in Europe, were no more likely to suffer a heart attack than those using nicotine replacement therapy or another quit-smoking drug.
They were also not at higher risk of depression or self-harm, the study found.
Describing the study as an â€œextensive analysisâ€ of the potential risks of Chantix, Aziz Sheikh, professor and co-director at the University of Edinburghâ€™s Center for Medical Informatics, said he considered it â€œhighly unlikely that varenicline has any significant adverse effects on cardiac or mental healthâ€.
â€œRegulators such as the United States Food and Drug Administration (FDA) should review its safety warning in relation to varenicline as this may be unnecessarily limiting access to this effective smoking cessation aid,â€ he said.
Chantix reduces both the craving for and pleasurable effects of cigarettes and is used by heavy smokers who find it difficult to quit. It is one of the biggest-selling stop-smoking drugs in the United States and Britain, and generated $647 million in revenue in 2014.
Investors had high hopes for the drug when Pfizer first launched it in 2006, but reports of mental health problems in users led FDA officials to order a â€œblack boxâ€ warning on the drugâ€™s label in 2009. Two years later, the FDA changed the Chantix label further to add a warning of increased heart risks for people who already have cardiovascular disease.
The latest research, published in The Lancet Respiratory Medicine journal, studied patients who had been prescribed either varenicline or Zyban, an anti-smoking drug from GlaxoSmithKline known generically as bupropion, to help them quit, or had used nicotine therapies such as patches, gum or lozenges.
Daniel Kotz, a professor at Germanyâ€™s Heinrich-Heine-University Dusseldorf who also worked on the study, said the findings suggested the risks were low so the benefits of Chantix should be made more widely available.
â€œSmokers typically lose three months of life expectancy for every year of continued smoking,â€ he said. â€œOur research supports the use of varenicline as an effective and safe tool to help people quit.â€
Smoking kills up to half of those who do it and is predicted to claim up to eight million lives a year worldwide by 2030 if current trends persist.
(Editing by Clelia Oziel)
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