Validation of clinical findings regarding traffic safety of medical drugs by means of a comparison with driving impairments under the influence of specific blood alcohol concentrations

Due to our ageing society with its growing need for individual mobility, increasing incidence of driving under the influence of medicinal drugs is expected. Physicians and patients need valid information about the driving impairing potential of medicinal drugs in order to choose those substances with the least impairing properties. The comparison of medical induced driving impairments with effects of specific blood alcohol concentrations (BAC) on driving performance is very helpful in order to interpret the clinical relevance of findings regarding traffic safety. The present study aimed to get alcohol calibration data in order to validate findings of clinical trials as conducted in the dynamic driving simulator of Würzburg. 24 healthy volunteers drove under the influence of 0.00%, 0.05% and 0.08% BAC through a representative set of driving scenarios. With alcohol, significant more driving mistakes have been observed, lane keeping performance deteriorated significantly and drivers drove significantly faster. Driving performance was not similar impaired for the different scenarios: In challenging tracking scenarios and in gap acceptance situations, effect of alcohol was more distinct than in simple tracking tasks. In order to demonstrate how data of the present study may be used for the interpretation of clinical findings, impairments on driving performance due to of carbamazepine and oxcarbazepine from a former study are compared with effects of 0.05% and 0.08% alcohol.