Fexofenadine Does Not Impair Driving Performance

First generation antihistamines, and some second generation antihistamines, may produce sedation and impairment of driving performance. Indeed, some states consider auto accidents that occur while a person is taking a sedating antihistamine in a category similar to driving under the influence of alcohol.

Fexofenadine is a second generation antihistamine, metabolically derived from terfenadine. Since fexofenadine is the metabolite formed after P-450 metabolism, there is no concern for drug accumulation with P-450 blockade. Additionally, fexofenadine is not reported to have any of the myocardial quinidine-like activity of its parent compound, terfenadine.

The current trial examined the effects on driving and psychomotor performance of standard and twice therapeutic doses of fexofenadine. The effects of fexofenadine when coupled with alcohol sufficient to produce a blood alcohol concentration just under the legal limit (0.05%) were also studied. A driver fatigue test originally developed in the 1970s which monitors subjects' capacity to maintain a constant speed and road position over one hour in a specially designed dual-control vehicle when accompanied by an instructor was employed. Active drug was administered in a variety of dosing schedules daily for five days.

Not only did fexofenadine not impair driving performance, it was actually found to improve driving performance in higher doses. Similarly, fexofenadine attenuated the deleterious effects of alcohol on driving performance. Fexofenadine does not impair capacity to drive, and, in higher doses, may by some CNS-activating mechanism improve driving performance and attenuate the negative effect of modest alcohol ingestion.

Vermeeren A, O'Hanton JF. J Allergy Clin Immunol 1998;101:306-311.