The influence of analgesic drugs in road crashes.

The involvement in road crashes of two classes of drug referred to as analgesics is discussed. Evidence for the effect on traffic safety of each drug group is examined in terms of their behavioural pharmacology and of the available epidemiological data. In the case of the antipyretic analgesics, such as aspirin, there is no evidence to suggest any causative involvement in road crashes. In view of the striking differences in the supply and manner of use of the legal and illegal narcotic analgesics, these are examined separately. The behavioural pharmacology of intravenously administered heroin suggests that any drug induced deficit in driving performance is not due to any effect on psychomotor function, but might be expected from the effect of the drug on mood states. Methadone, as used in treatment schedules for narcotic dependence produces no significant effect on measures of human skills performance. Epidemiological data are contradictory though the suggestion is that the involvement of the narcotic analgesic drugs in road crashes is unlikely to be a source of significant concern. A suggestion is made that a closer examination be undertaken of the involvement in road crashes of the more widely available narcotic drugs codeine and propoxyphene when they are taken together with alcohol.