Thousands of traffic accidents could be avoided every year if people who use anti-anxiety drugs such as Valium did not drive, say authors of a study published Friday.
Drivers taking such anxiety medications during the day are more than twice as likely to be involved in traffic accidents as those not taking the drugs, according to the study in The Lancet, a British medical journal.The risk of accidents for people under the age of 45 is more than three times greater if taking the drugs, the study said.
"The current warnings are that if you feel drowsy, don't drive. That needs to be changed," said Dr. Tom MacDonald, the clinical pharmacologist from the University of Dundee in Scotland, who led the study. "I would say if you use these drugs, don't drive."
He argued that thousands of lives could be saved worldwide if drivers avoided the drugs.
But Dr. Desmond O'Neill, a geriatrician at the Center for Mobility Enhancement at Adelaide and Meath Hospital in Dublin, Ireland, viewed the study's conclusions with caution.
"They've made us think hard, but it still isn't enough evidence to tell people not to drive," he said. "Is it the illness or the medication? If you're that agitated that you need the drug, maybe that's the problem."
The results could be attributed to people whose personalities make them prone to getting into more risky situations, he said. "The jury is still out on this one."
Tranquilizers such as Valium, generically known as diazepam, are commonly used to treat anxiety, other stress-related disorders and muscle spasms. They are the world's most commonly prescribed tranquilizers.
Patients usually feel drowsy on those drugs in the first few days of taking them, but accidents occur at the same rate regardless of whether drowsiness occurs, MacDonald said.
Jeff Soper, a spokesman for Hoffman LaRoche, the Swiss maker of Valium, said his company's warning labels for Valium are clear.
"Patients should be cautioned against engaging in hazardous occupations requiring complete mental alertness, such as operating machinery or driving a motor vehicle," he said, reading from the label.
The researchers compared the records of all prescriptions dispensed in the Dundee area with all 19,386 traffic accidents the local police responded to between April 1992 and June 1995. A total of 1,731 people involved in those accidents were taking one of the drugs examined in the study.
Of the accidents involving those 1,731 people, four included fatalities. Of those, three drivers were taking anti-anxiety drugs on the day of the accident and the fourth driver had taken anti-anxiety drugs during the study period.
The researchers looked at four groups of medications. Besides anti-anxiety drugs taken during the daytime, they also examined antidepressants such as Prozac and other drugs that act on the brain.
Only the anti-anxiety drugs were associated with an increased risk of traffic accidents. Antidepressants showed no link and neither did any sleeping pills, except for one - zopiclone.