Drugs and medicines that are suspected to have a detrimental impact on road user performance. ROSITA. Deliverable D1

Driving is a complex task where the driver continuously receives information, analyses it and reacts. Substances that have an influence on brain functions or on mental processes involved in driving will clearly affect the driving performance. Different studies provide information about the influence of illicit drugs and licit medicines on driving performance: They can be classified into three main types: epidemiological studies, pharmaco-epidemiological studies and experimental studies.
Epidemiological studies are necessary to estimate the importance of the problem. [...] Pharmaco-epidemiological studies are very useful as they compare the number of accidents in drivers for whom medicines are prescribed with the number of accidents in a matched control population. The results of the major reports are summarised in the present work. However, this kind of study is difficult to perform with illicit drugs, for easily understandable practical and ethical reasons.
Experimental studies consist in the administration of different doses of medicines or of placebo to selected volunteers. The effects on psychomotor performance and/or on driving skills are measured by laboratory tests, in driving simulators or by real driving experiments. While there is an abundant literature on the subject, methodologies are not well standardised and comparisons of different studies with sometimes conflicting results are difficult to perform.
Illicit drugs possibly influencing driving performances are then presented, with epidemiological and experimental data if available:
Cannabis (used as marihuana, hashish, );
Opiates (mostly heroin);
Cocaine (free base, crack,);
There are few studies of the influence of amphetamines and designer amphetamines (XTC, Eve, ...) on psychomotor function;
Finally, hallucinogens (GHB, LSD, magic mushrooms, mescaline,).
Medicinal drugs affecting driving performance are finally presented. Psychoactive medicines can modify behaviour and experience, causing somnolence, loss of psychomotor co-ordination, balance or sensory disturbances,...:
Benzodiazepines, Antidepressants, Neuroleptics, Narcotics and opioid analgesics; Antihistamines.
Some classifications have been proposed to categorise medicinal drugs according to their influence on driving ability (categories ranging from no impairment to severe impairment): the system proposed by the Dutch study group of Wolschrijn provides a categorisation of about 570 drug doses/formulations and the BLT in Belgium has classified 180 medicines.
The use of categorisation and warning (sticker or label) systems in different European countries (Germany, the Netherlands, the Nordic countries, Italy, France) is discussed and finally, a comparison of the different systems is presented in an overview table. (Extract of the publication)