Acute intake of benzodiazepines has shown to be followed by concentration dependent deterioration of psychomotor performance and cognition in controlled experimental studies with volunteers. Whether similar concentration-effect relationships exist in a more diverse population of benzodiazepine users is uncertain. We wanted to address this question by studying a population of apprehended impaired drivers. Our data indicated highly different benzodiazepine intake patterns amongst the drivers during the period prior to apprehension. Impaired subjects had significantly higher blood levels of diazepam and oxazepam than those not impaired. The risk of being assessed as impaired did rise with increasing benzodiazepine blood level. This corresponded to a similar rise in such risk in a reference group where alcohol was detected. Of the various characteristics studied for the studied subjects the blood concentration of benzodiazepines was the only, which was related to clinically assessed impairment. The results open for further studies and discussion on legal limits for benzodiazepines in relation to driving. (Author/publisher) For the covering abstract of the conference see ITRD Abstract No. E201067.
Samenvatting