Fexofenadine - A review of its use in the management of seasonal allergic rhinitis and chronic idiopathic urticaria

Fexofenadine, the active metabolite of terfenadine, is a selective histamin e H-1 receptor antagonist that does not cross the blood brain barrier and a ppears to display some anti-inflammatory properties. Fexofenadine is rapidl y absorbed (onset of relief less than or equal to 2 hours) and has a long d uration of action, making it suitable for once daily administration. Clinical trials (less than or equal to 2 weeks' duration) have shown fexofe nadine 60mg twice daily and 120mg once daily to be as effective as loratadi ne 10mg once daily, and fexofenadine 120mg once daily to be as effective as cetirizine 10mg once daily in the overall reduction of symptoms of seasona l allergic rhinitis. When given in combination, fexofenadine and extended r elease pseudoephedrine had complementary activity. Fexofenadine was effecti ve in relieving the symptoms of sneezing, rhinorrhoea, itchy nose palate or throat, and itchy, watery, red eyes in patients with seasonal allergic rhi nitis. There were often small improvements in nasal congestion that were fu rther improved by pseudoephedrine. Fexofenadine produced greater improvemen ts in quality of life than loratadine to an extent considered to be clinica lly meaningful, and enhanced patients' quality of life when added to pseudo ephedrine treatment. Although no comparative data with other HI antagonists exist, fexofenadine 180mg once daily was effective in reducing the symptom s of chronic idiopathic urticaria for up to 6 weeks. Fexofenadine was well tolerated in clinical trials in adults and adolescent s and the adverse event pro file was similar to placebo in all studies. The most frequently reported adverse event during fexofenadine treatment was h eadache, which occurred with a similar incidence to that seen in placebo re cipients. Fexofenadine does not inhibit cardiac K+ channels and is not asso ciated with prolongation of the corrected QT interval. When given alone or in combination with erythromycin or ketoconazole, it was not associated wit h any adverse cardiac events in clinical trials. As it does not cross the b lood brain barrier, fexofenadine is free of the sedative effects associated with first generation antihistamines, even at dosages of up to 240 mg/day. Conclusions: fexofenadine is clinically effective in the treatment of seaso nal allergic rhinitis and chronic idiopathic urticaria for which it is a su itable option for first-line therapy. Comparative data suggest that fexofen adine is as effective as loratadine or cetirizine in the treatment of seaso nal allergic rhinitis. In those with excessive nasal congestion the combina tion of fexofenadine plus pseudoephedrine may be useful. In clinical trials fexofenadine is not associated with adverse cardiac or cognitive/psychomot or effects.