A study was commissioned in 1988 by several Dutch organisations, to design a new system for classifying drugs suspected of impairing driving. The study design assumed that such classification is possible by using questionnaires to obtain expert opinions. After preliminary enquiries, the final questionnaire was sent to 45 recognised experts in Europe, North America, and Australia. Its purposes were to determine whether there was a consensus about the severity of drug effects, and whether researchers on psycho-active drugs could classify these drugs. The new classification should enable available data and expert ratings to be translated into easily accessible information, and experts to agree on the classification of drugs. Experts were presented with each others' ratings before a final consensus was reached. Three major categories and eight subcategories were proposed, which were related to the severity of their effects on driving. The drugs investigated were tranquillisers, antihistamines, antidepressants, and hypnotics. The feasibility of a new system was demonstrated. Its final implementation must follow a series of concerted actions for harmonising research methodologies, registration procedures, package warning systems, and traffic safety regulations.
Abstract