Fexofenadine (fex oh fen' a deen) hydrochloride (Allegra - Hoechst Marion Roussel) has been approved by the US Food and Drug Administration for treatment of seasonal allergic rhinitis. An active metabolite of terfenadine, fexofenadine is being heavily advertised as "nonsedating...without 'black box' warnings."

Fexofenadine (Allegra, and others) is the most recent second-generation H₁-antihistamine to become available over the counter (OTC). Cetirizine (Zyrtec, and others) and loratadine (Claritin, and others) are already available OTC. Cetirizine can be sedating in usual doses. Loratadine can be sedating in higher-than-usual doses. Fexofenadine remains nonsedating even in higher doses.

With the coming of spring, direct-to-consumer (DTC) advertisements in newspapers, in magazines and on television are urging people with seasonal allergies to ask their doctors about one or another of the newer, non-sedating antihistamines.

Levocetirizine (Xyzal - UCB/Sanofi-aventis), the active enantiomer of the second-generation H₁-antihistamine cetirizine (Zyrtec), has been approved by the FDA for treatment of seasonal and perennial allergic rhinitis (SAR and PAR) and chronic idiopathic urticaria in adults and children 6 years of age and older. Cetirizine has been approved by the FDA for over-the-counter use and may also become available generically in the US. Levocetirizine has been available in Europe since 2001.

Quzyttir (TerSera), an IV formulation of the second-generation H1-antihistamine cetirizine, has been approved by the FDA for treatment of acute urticaria in patients ≥6 months old. Oral formulations of cetirizine (Zyrtec, and others) have been for sale over the counter for years. Quzyttir is the first parenteral formulation of a second-generation H1-antihistamine to become available in the US; parenteral formulations of two first-generation H1-antihistamines, diphenhydramine (Benadryl, and others) and hydroxyzine (Vistaril, and others), have been available for many...

The FDA has approved the marketing of loratadine (Claritin - Schering), a second-generation H₁-antihistamine, without a prescription. The drug was also recently approved for OTC use as Alavert (Wyeth) and other generics are expected.

Azelastine hydrochloride, a histamine-H1 receptor antagonist, has been marketed as a 0.1% nasal spray (Astelin - Wallace) for treatment of seasonal allergic rhinitis. Corticosteroid and cromolyn sodium nasal sprays are also available for this indication (Medical Letter, 37:5, 1995). Cromolyn sodium (Nasalcrom) has now been approved for over-the-counter use.

Desloratadine (des lor at' a deen; Clarinex - Schering), an active metabolite of the H1-receptor antagonist loratadine (Claritin), has been approved by the FDA for oral treatment of allergic rhinitis and chronic urticaria in patients at least 12 years old. The patent for loratadine expires in December 2002, and generic or over-the-counter versions are expected.

View the Comparison Table: Some Oral Drugs for Allergic Rhinitis

A new formulation of the H1-antihistamine azelastine hydrochloride 0.1% nasal spray (Astepro - Meda) has been approved by the FDA for treatment of seasonal allergic rhinitis (SAR) in patients ≥12 years old and is being heavily advertised to the public on radio, television and the Internet. All azelastine products require a prescription.