Classification of medicines according to their influence on driving ability

Within the scope of an information campaign of the Belgian Institute for Ro ad Safety an attempt was made to classify 179 medicinal drugs from 9 therap eutic groups, listed in the Belgian <<Commented Repertory of Drugs-1997>>, according to their effect on driving performance. The categorisation was ba sed on literature data from about 500 references and used the system propos ed by Wolschrijn et al [1]: 7 classes ranging from no effect (I) over minor and moderate (II.1,II.2) to severe effects (III), completed with the respe ctive * categories (I*,II*,III*) for presumed classes with insufficient sci entific data. Forty-two drugs (24%) were considered having severe effects ( III/III*). Only 28/179 molecules (16%) were classed in I/I*: no hypnotics-s edatives (33), anticonvulsants (10), antidepressants (25), neuroleptics (29 ), nor narcotic analgesics and antitussives (18) were listed in this no-eff ect category, while for 7/24 antihistamines (5/20 H1 and 2/4 H2), 12/20 bet a blockers and 9/10 central stimulants the effect was considered negligible . Antidiabetics were not classified, as the danger lies in the risk of hypo glycemia due to inadequate use. The classification of the molecules proved to be problematic due to the lac k of study data (42% of molecules in presumed categories) and the diversity in the study protocols. The effect on driving ability is dose-dependent an d time-related, which makes the use of a single category inadequate; the ef fect further depends on co-ingestion of other medicines or alcohol, the dev elopment of tolerance Mel the condition of the subject. Physicians and phar macists can use the proposed categorisation as a scientific base for guidin g their patients, but should take into account the factors involved for eac h patient when estimating the driving ability.