11/10/2013 09:39 BST

Anti-Smoking Pills 'Do Not Increase Suicide Risk'

Patients prescribed stop-smoking pills do not suffer an increased risk of suicide compared with those using nicotine patches and gum, a study has found.

Scientists say new research will alleviate safety concerns over the drugs Zyban and Champix, some of the most popular stop-smoking drugs worldwide.

One million people in the UK were prescribed Champix (varenicline), known as Chantix in the US, and Zyban (bupropion), in 2011.


The drugs work by cutting cravings but fears were raised after patients reported depression, suicidal thoughts and anxiety.

Researchers from the University of Bristol set out to examine whether patients prescribed Champix and Zyban were at an increased risk of suicide, self-harm and depression, compared with users of nicotine replacement therapy.

Bupropion is used to treat depressive illnesses in some countries, though it is not licensed for this purpose in the UK.

However, concerns that these drugs may increase the risk of suicide have led to safety warnings by regulatory agencies including the UK Medicines and Healthcare Products Regulatory Agency and the US Food and Drug Administration.

Findings from this large-scale study aimed to assess the risk of psychiatric events in patients prescribed varenicline or bupropion compared with those using nicotine replacement products such as patches and gum.

Researchers analysed data from the medical records of 119,546 adults who had used a smoking cessation product between September 1 2006 and October 31 2011.

Using linked data from the Office for National Statistics mortality data and hospital episode statistics, the team were then able to assess the rate of treated depression, self-harm and suicide in 31,260 (26%) patients prescribed varenicline, 6,741 (5%) patients prescribed bupropion and compare this with 81,545 (68%) people using nicotine replacement therapies.

The findings, which used three different analytical methods, showed no clear evidence of an increased risk of treated depression or suicidal behaviour for patients prescribed varenicline or bupropion compared to those taking nicotine replacement therapies.

Dr Kyla Thomas, one of the study's lead authors, said: "Given the concerns and accompanying safety warnings for these drugs, these findings are reassuring for users and prescribers of smoking cessation medicines."

Co-author Professor David Gunnell added: "These findings support those of our earlier study in a larger, more comprehensive assessment of this important issue."

"They will be of interest to patients, prescribers and drug regulators."

In 2011 research suggested that taking Champix increased the risk of heart attacks and stroke by more than 72%.

The study, published in the Canadian Medical Association Journal, analysed data for more than 8,000 people from 14 medical 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 a placebo.

The paper, entitled 'Smoking cessation treatment and the risk of depression, suicide and self-harm in the Clinical Practice Research Datalink: a Prospective Cohort Study', is published today in the British Medical Journal.

For advice or help, or if you have been affected by suicide, visit the Samaritans website.