A spate of people having fits and seizures while taking the new anti-smoking drug Zyban has raised concern among doctors about its safety.

A spate of people having fits and seizures while taking the new anti-smoking drug Zyban has raised concern among doctors about its safety.

The Department of Health said it was monitoring all adverse effects of the drug, and seizures were one of the known side-effects. The non-nicotine drug, which helps smokers give up, has been available in Britain since June.

Official figures, released yesterday, show that 862 people have reported adverse effects, including fits, insomnia, anxiety, and dizziness. A Department of Health spokeswoman said at least 29 people reported suffering fits or seizures. "It is a known side-effect and the Medical Control Agency is keen to draw doctors' attention to the people who are most likely to suffer from fits from taking the drug, so these people are not prescribed it," she said.

Next year the National Institute of Clinical Excellence is due to assess both the clinical efficacy and cost of Zyban and nicotine replacement patches, and will take into consideration the level of adverse reactions, she said. The number of people being prescribed the drug is not yet available, but the Government believes its widespread use could bring the NHS considerable savings on the £1.7bn annual cost of treating smoking-related illness.

The chance of suffering aseizure is reported to be less than one in a thousand people, but doctors from one hospital in Manchester said they have seen higher numbers than this.

Dr Kevin Raynard, an accident and emergency consultant at Wythenshawe Hospital, said: "We have had five people with side-effects from the drug - three having fits - in the last six weeks. I'm surprised. I don't think our locum GPs will have put 5,000 people on this drug ... It is highly unlikely a fit could be life-threatening. But you could injure yourself and once you've had one, it could have a huge impact on lifestyle - preventing people from driving, for example."

One of people treated at the hospital was an ambulance driver who had a fit while responding to an emergency call and crashed the vehicle.

Zyban has been hailed as a wonder drug and research has shown that it is twice as effective as nicotine patches. Zyban is the trade name for bupropion hydrochloride SR and it works by altering the balance of chemicals in the brain and reducing the craving to smoke.

Patients begin taking the drug while still smoking, and set a "quit date" for the second week of therapy. A large study reported in the New England Journal of Medicine found that 30 per cent of those treated were not smoking a year later.

People who are taking anti-depressant drugs, those who have a history of epilepsy or people with current or previous eating disorders should not be prescribed the drug, the manufacturer, Glaxo Wellcome, says.

Dr Howard Marsh, spokesman for Glaxo Wellcome, said research showed there was less than a one in a thousand chance of a person having a fit if they took the drug and its use was continually monitored. "There is this potential for a serious side-effect, which is seizures," he said.

"It is rare and we have known about it for some time. There is a similar risk with several other commonly prescribed drugs such as antidepressants. You can never say any drug is completely safe. Any side-effects that are reported we take very seriously."