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Medline ® Abstract for Reference 90

of 'Pharmacotherapy of allergic rhinitis'

Randomized double-blind comparison of cetirizine and fexofenadine after pollen challenge in the Environmental Exposure Unit: duration of effect in subjects with seasonal allergic rhinitis.
Day JH, Briscoe MP, Rafeiro E, Hewlett D Jr, Chapman D, Kramer B
Allergy Asthma Proc. 2004;25(1):59.
There is published evidence that cetirizine has a longer duration of effect than fexofenadine. This study compared duration of effect and other measures of efficacy of cetirizine, 10 mg; fexofenadine, 180 mg; and placebo in allergic subjects exposed to pollen in the Environmental Exposure Unit. Eligible subjects (n = 575) were exposed to ragweed pollen (day 1, 7 hours; day 2, 5 hours) and randomized in double-blind fashion to once-daily cetirizine, 10 mg; fexofenadine, 180 mg; or placebo. The total symptom severity complex (TSSC) score, the primary efficacy variable, was based on four rhinoconjunctivitis symptoms rated at 20-minute intervals. Treatment evaluation was divided into three periods: period 1 TSSC, average of 15 scores obtained 0-5 hours after the first dose; period 2 TSSC, average of 9 scores obtained 21-24 hours after the first dose; and period 3 TSSC, average of 6 scores obtained 0-2 hours after the second dose. The primary efficacy end point was the change from baseline TSSC at period 2. Baseline TSSC was the final pretreatment score on day 1 and was 9.7 for cetirizine, 9.8 for fexofenadine, and 9.7 for placebo. For the primary efficacy end point, the reduction in baseline TSSC at period 2 was greater for cetirizine (-3.6) comparedwith fexofenadine (-2.7; p<0.001) and placebo (-2.0; p<0.001), representing a 33% greater reduction for cetirizine versus fexofenadine. Cetirizine continued to reduce TSSC more than fexofenadine (-5.2 versus -4.6; p = 0.017) and placebo (-3.9; p<0.001) (period 3). Similar efficacy was observed in period 1 for both active treatments. Treatment-related adverse events were similar in all groups with an incidence of somnolence of 1.3% for both active medications. In conclusion, cetirizine produced a 33% greater reduction in SAR symptoms over the 21- to 24-hour interval after the first dose and for 40 minutes after the second dose, indicating a superior and longer duration of effect, which is relevant because both are once-daily medications. Onset of action was comparable and both treatments were safe and well tolerated.
Division of Allergy and Immunology, Department of Medicine, Queen's University and Kingston General Hospital, Kingston, Ontario, Canada.