Benzodiazepines and traffic safety:forensic, analytical-toxicological and epidemiological aspects of driving under the influence of benzodiazepines

Driving under the influence of alcohol, illicit and medicinal drugs (e.g. benzodiazepines) is under discussion world-wide because many studies have shown that its use is associated with impaired driving and increased accident risk despite sometimes conflicting results. In The Netherlands, the number of fatally inured road users was slightly under 800 in 2007. Alcohol is the most frequently used psychoactive substance in drivers. The prevalence of psychoactive prescription drugs in drivers is expected to be about 5%. In order to increase traffic safety, policy makers in The Netherlands have been discussing new legislation that could reduce the use of illicit drugs as well as psychotropic medicinal drugs in traffic. Benzodiazepines are the most common detected medicinal drugs in drivers. In general, indications for benzodiazepine use are related to the sedative-hypnotic, muscle relaxant, anxiolytic and/or anticonvulsant effects of this group of substances. A reason for concern is the inappropriate (long term) use of benzodiazepines and the use of benzodiapines without prescription i.e. as drug of abuse. The objectives of this thesis are to study how the exposure of drivers to benzodiazepines can be measured in different body fluids and to examine the effects of this exposure on driving performance and accident risk in view of legal procedures related to traffic and patient safety and enforcement. Although the focus of this thesis is on the use of benzodiazepines, the use of concomitant alcohol or other psychoactive substances in real traffic situations is common practice and is integrated in our work