Tom MacDonald on drugs and driving

A study says that around 110 lives a year could be saved in the UK if people taking certain types of benzodiazepines, including valium, did not drive.

It advised that people taking one type of the drugs - anxiolytic benzodiazepines, taken for anxiety - and the related drug Zopliclone should be told not to drive.

The researchers, from the Medicines Monitoring Unit at Ninewells Medical School in Dundee, found that taking benzodiazepines, especially in combination with alcohol, increased a driver's chance of having an accident.

One of the researchers, Dr Tom McDonald, said: "The question is what we do about making regulations about whether people should drive while taking these drugs."

Dr Tom McDonald: Difficult to fix drug-blood level

It would be for society, not him, to decide.

The study was prompted by previous European Commission research which showed that psychotropic drugs might play a part in at least 10% of deaths or serious injuries caused by road traffic accidents.

Another study had shown that elderly people who took benzodiazepines ran an increased risk of having accidents.

However, the new research shows people under 45 who take the drugs are more likely to have accidents.

Dr Tom MacDonald: people should not take some tranquillisers and drive

This may be because young people are more likely to have been on the drugs for a shorter period, meaning they may not have developed a tolerance to them.

The researchers studied information on more than 400,000 people living in Tayside whose details were held on a pharmaceutical database.

They compared this information with details about people involved in first-time road traffic accidents over a three-year period.

They found that 1,731 Tayside drivers on prescribed drugs had had accidents.

Some 235 had taken benzodiazepines on the day of the accident.

The researchers also looked at other prescribed drugs which are known to have a range of effects, including increased drowsiness and delayed reaction.

Richard Hannaford on the peril of driving on drugs

They said accidents were more likely among people who took certain types of benzodiazepines.

They believed this might be because anxiolytic benzodiazepines were more likely to be taken during the day, whereas other types of the drug were taken at night.

Unlike previous studies, the researchers found no link between taking anti-depressants and road accidents.

Walking and cycling

Writing in The Lancet, Desmond O'Neill, of the Centre for Mobility Enhancement at Adelaide and Meath Hospital in Dublin, said the new research did not prove the link between benzodiazepines and driving accidents.

Young people who take anti-anxiety drugs are more at risk of crashing than the elderly

But he said it was a step forward in research on the subject and called for a larger study which would encompass all forms of mobility, including walking and cycling.

He said doctors should bear the research in mind and advise patients not to drive if they cannot be trusted not to mix benzodiazepines and alcohol.

Doctors should also consider if the condition which the drugs were treating could also be a factor in increased driving accidents.

"Most importantly," he said, "prescribers should query whether the patient really needs a benzodiazepine, and if so, whether it needs to be long acting."

Doctors were warned earlier this year against over-prescribing benzodiazepines and were told that driving while taking tranquillisers could be dangerous.

The Department of Transport said it would consider the new research carefully.