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Use of Common Sedatives Dramatically Increases Risk for Collisions

May 21, 2009

A new study has linked motor vehicle collisions with the use of benzodiazepines, drugs used as sedatives and muscle relaxants. The study reports that there is a 60 per cent increase of motor vehicle collision risk when a person is driving under the influence of these drugs.

"International studies have shown that benzodiazepines are one of the most prevalent classes of drugs found in the blood tests of people injured or killed in motor vehicle collisions, "says Dr. Mark Rapoport, lead investigator of the study and a geriatric psychiatrist at Sunnybrook Health Sciences Centre. "The present study provides us with a better understanding of the magnitude of the relationship between these drugs and collisions, and in particular the propensity of these drugs to impair maintenance of road position."

Estimates indicate that 1.2 million people worldwide are killed in motor vehicle collisions annually, with up to an additional 50 million people injured in these types of accidents. In 2005, five benzodiazepines were listed among the top 50 drugs prescribed in the United States. These same drugs are prescribed for more than 15 per cent of older adults in Ontario, Canada. Given these large numbers, the study advocates for a reduction in prescriptions for benzodiazepines, especially in light of previous studies that have shown these drugs to cause drowsiness and dizziness among people of various ages, while causing falls among older adults.

"We realize that more research is needed to address the relative role of anxiety, insomnia, and other psychiatric illness with the use of benzodiazepines, as well as short-term use of the drug on driving ability," says Dr. Rapoport, also an Assistant Professor in the Department of Psychiatry at the University of Toronto. "Nonetheless, clinicians have a duty to keep their patients informed about the impact of these drugs while driving. There is evidence that the risks associated with these drugs are especially highest within the first month of prescription."

Overall, the study underlines the need for policy makers in North America to consider making the risks associated with these drugs better known to the public, while legislative changes may be required to further prevent benzodiazepine users from getting behind the wheel.

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