Possible side effects

dry mouth headache insomnia Zyban should not be prescribed for patients with a history of epilepsy or seizures

Within 10 seconds of inhaling from a cigarette, a concentrated dose of nicotine is delivered directly to the brain.

This 'rush' stimulates the release of a number of naturally occurring neurotransmitters in the brain.

Over time the effects on these neurotransmitters - particularly dopamine and noradrenaline - cause a smoker to become physically addicted to nicotine.

When smokers quit, neurotransmitter levels are altered causing cravings, anxiety and irritability.

Zyban acts on the addiction process by helping to put these levels back to normal.

A study published in the New England Journal of Medicine found that almost one in three people (30.3%) treated with Zyban were not smoking at one year.

In this study, Zyban was found to be almost twice as effective as a nicotine patch in helping people to quit smoking and to stay off tobacco for at least one year.

Biochemical basis

Dr Chris Steele, a Manchester GP and expert on smoking, said: "Most smokers do not continue to smoke cigarettes out of habit, but because they are addicted to nicotine.

"Zyban is the first non-nicotine prescription medication that tackles the biochemical basis of nicotine addiction."

Zyban is good, but it is not a silver bullet

Clive Bates, Action on Smoking and Health

Health Secretary Alan Milburn said the treatment, which will cost the NHS �42.85 per month for each patient prescribed the drug, was "good news for the 70% of smokers who say they want to give up".

He added: "We have already invested �30 million over two years on setting up specialist smoking cessation services in the NHS and this announcement is another step towards ensuring that our health service leads the world in its smoking cessation services."

Clive Bates, director of the anti-smoking charity Action on Smoking and Health (ASH) disputed the figures from the Zyban study and said other treatments were also effective.

However, he said: "The launch of Zyban is good news for smokers.

"This is a significant development because it means that smoking cessation treatment will become a mainstream part of the NHS. Doctor will now have a tool with which they can help people to give up smoking."

However, he added: "Zyban is good, but it is not a silver bullet - smokers are still going to need lots willpower and determination to keep trying."

Dr Mark Britton, chairman of the British Lung Foundation, said: "Zyban is the first new innovation to help smokers kick the habit that we've seen in almost a decade.

"We welcome this exciting advance to help smokers break their addiction."

Smoking costs �1.7billion to the NHS every year in terms of GP consultations, prescriptions and hospital care.

Zyban available in tablet form on prescription and is taken as a two-month course.

Developed by Glaxo Wellcome, Zyban has already been licensed in the US, Canada and Holland.