Comparative study of terfenadine and cetirizine in hay fever: assessment of efficacy and central nervous system effects.

A daily dose of either terfenadine 120 mg or cetirizine 10 mg was compared in two parallel groups of patients suffering from hay fever. According to a double-blind, double-dummy, randomized design, 28 patients were treated with one of the two drugs once daily in the morning for 2 weeks during the 1990 grass pollen season. The severity of nasal congestion, rhinorrhea, sneezing, nasopharyngeal itching and itchy, watery, red eyes was evaluated by the investigator after a 1-week run-in period and at the end of the treatment. The patients made a daily record of the severity of symptoms on a diary card. In addition, drug-related central nervous system (CNS) effects were assessed at baseline and at the end of the treatment by neuropsychological tests aimed at investigating selective and sustained attention, visuomotor abilities and anxiety, and by quantitative, bit-mapped EEG. Both terfenadine and cetirizine produced a significant improvement in symptoms at endpoint without any significant difference between the two drugs. Drowsiness was referred by one patient in each treatment group. No significant impairment of psychomotor performance occurred with either drug. Quantitative EEG showed a significant power increase in the relative (%) delta band in both groups of treated patients. Although the difference was not statistically significant, a tendency towards greater involvement of the CNS was observed with the use of cetirizine. In conclusion, the results of this study confirm that terfenadine and cetirizine are equally effective in the management of hay fever. Some differentiated untoward EEG changes were also observed in relation to the drugs used, without any variation in neuropsychological performance.