A comparison of medicinal drugs detected in blood of suspected impaired drivers with data on the use of driving impairing medicines in the Netherlands

This study presents the analytical results of blood samples of suspected impaired drivers during a four year period and compares the medicinal drugs detected in the blood samples with the use of these driving impairing medicines in The Netherlands. In 2009-2012, the blood alcohol concentrations of 9047 samples have been determined and 82 per cent of the samples tested positive. In addition, 3038 blood samples have been analyzed for drugs and in 94 per cent of the cases drugs were detected. Medicinal drugs were detected in 33 per cent of the drug cases, including poly-medicinal drug use in 37 per cent of the positive medicinal drug cases. Anxiolytics have the highest prevalence of 19 per cent in the population of suspected impaired drivers. Followed by hypnotics and sedatives (13 per cent), medicinal opiates (6.9 per cent), antidepressants (4.5 per cent) and antiepileptics (1.1 per cent). The prevalences of these medicinal drug groups in the general Dutch population are about two or three times lower for anxiolytics (6.9 per cent), hypnotics and sedatives (5.5 per cent), and antiepileptics (0.34 per cent), compared to suspected impaired drivers. Medicinal opiates have about the same prevalence in both populations, which could be a result of the criteria used for the categorization of these substances. Antidepressants have a higher prevalence in the general Dutch population possibly due to differences in characteristics of the study populations (e.g. tolerance development and age). Overall, the results show that the prevalence of the selected medicinal drugs in suspected impaired drivers is higher than the prevalence of medicinal drugs in the general population. More research is needed to study the prevalence of all medicines that affect the driving performance.