SOFT - TIAFT 1998 Scientific Session 8 Friday October 9, 1998
Click Picture Viviane A. Maes*, Olivier E. Grenez1, Corinne J. Charlier2, Herlinde C. Smet3, Alain G. Verstraete4, Robert M. Wennig5

Academisch Ziekenhuis-VUB, Laarbeeklaan 101, 1090 Brussels*; pharmacist, Le Roeulx1; CHU Sart Tilman Liège2; Poison Control Centre Brussels3; UZ Gent4; CU Luxembourg5

In order to provide physicians and pharmacists with a scientific base for guiding their patients on the effects of drugs on driving performance, an attempt was made to categorize 179 medicinal drugs from 9 therapeutic classes listed in the Belgian "Commented Repertory of Drugs-1997", based on literature data from about 500 references. These 179 molecules are available in 241 (single drug) and 100 (associations) registered medicines. The package insert mentions the possible influence or absence of effect on driving for 78% (single) and 48% (associations) of these medicines.

The classification was based on the system of Wolschrijn et al (1991): 7 categories ranging from no effect (I) over minor and moderate (II1,II2) to severe effects (III), completed with the respective * categories for assumed classes with insufficient scientific data. A total of 28/179 molecules (16%) were considered having no influence (I/I*): 1/33 hypnotics-sedatives (0/4 barbiturates and 1/25 benzodiazepines), 0/10 anticonvulsants, 0/25 antidepressants, 0/28 neuroleptics, 0/19 narcotic analgesics and antitussives, 6/24 antihistamines (4/20 H1 and 2/4 H2), 11/20 beta blockers, 3/10 antidiabetics and 7/10 central stimulants.

The categorization of the molecules proved to be problematic. The lack of study data is reflected in the number of * categories (50%), this fraction being variable in the different drug groups e.g. antihistamines 0%, benzodiazepines 32%, neuroleptics 71%. The diversity in the study protocols makes an unequivocal classification impossible and emphasizes the need for standardization. It is obvious that the effect on driving ability is dose-dependent and time-related, which makes the use of a single category inadequate; co-ingestion of other medicines or alcohol, and development of tolerance further complicate the problem. Moreover the study data seldom relate the observed psychomotor performances with measured plasma concentrations, while this relation may be important in future traffic legislation. Physicians and pharmacists should take these considerations into account when estimating the driving abilities of their patients.

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