A placebo controlled study was carried out which examines the dose-response relationship for three therapeutic doses of the antihistamine, dexchlorpheniramine (1, 2 & 4 mg), alone and in combination with a 'social' dose of alcohol (0.75 g/kg). The study was designed to examine the relationship between impairment in psychomotor tasks which examine aspects of driving skills and the concentrations of dexchlorpheniramine and alcohol in the blood. Blood samples were taken at regular intervals across the 250 minute sessions and psychomotor testing was carried out at similar time intervals. The results of this study indicate that although some individuals may be significantly impaired after a single therapeutic dose of dexchlorpheniramine (2 or 4 mg), they do not necessarily experience subjective markers of impairment, such as sedation and a perceived reduction in co-ordination. This is likely to pose difficulties for some drivers in recognising dexchlorpheniramine induced driving impairment. (A)
Abstract