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Department of Pharmaceutical Services

Allegra (fexofenadine)

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Dear Physician,

Allegra (fexofenadine) is now available in generic formulations of 30mg, 60mg and 180 mg tablets. This second generation antihistamine joins loratadine (Claritin) which is generic and over the counter (OTC). Zrytec (cetirizine) and Clarinex (desloratadine) provide no therapeutic or safety advantage and should be reserved for patients intolerant or unresponsive to generic second generation antiheistamines. Branded Zyrtec and Clarinex average $2 a tablet while generic loratadine (Claritin) is as low as 5 cents per tablet. Genereic fexofenadine (Allegra) is $0.50 - $1.00 less expensive than branded antihistamines.

Differences in overall efficacy and safety between second-generation antihistamines when administered in equivalent dosages have not been demonstrated in clinical studies. Studies evaluating the CNS effects of second-generation antihistamines suggest that CNS effects of fexofenadine (Allegra), desloratadine (Clarinex) and loratadine (Claritin) at recommended doses closely resemble those of placebo. Cetirizine has demonstrated mixed results, with no difference from placebo shown in some studies but modest although statistically significant deterioration in psychomotor test results and cognitive abilities identified in others. Cetirizine (Zyrtec) is sometimes classified as a mildly sedating anti-histamine.

Summary: Generic loratadine (Claritin) and fexofenadine (Allegra) provide the physician with two efficacious and safe second generation anti-histamines.  Use of Clarinex and Zyrtec should be reserved for patients intolerant or unresponsive to generic second generation antihistamines.

References:
1. Golightly Larry K, Greos Leon. Second-generation antihistamines-actions and efficacy in the management of allergic disorders. Drugs. 2005;65(3):341-384

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