Cetirizine (Zyrtec - Pfizer), a histamine H 1 -receptor antagonist, has been approved by the US Food and Drug Administration for treatment of seasonal allergic rhinitis, perennial allergic rhinitis and chronic idiopathic urticaria in adults and children more than 12 years old.

Cetirizine (Zyrtec, and others) and cetirizine/pseudoephedrine (Zyrtec-D) are becoming available without a prescription this month for treatment of allergic rhinitis and urticaria in adults and children. Cetirizine is the second of the second-generation H1-antihistamines to become available over the counter. Loratadine (Claritin, and others) was the first.Cetirizine has been shown to be more effective than loratadine in suppressing histamine-induced wheals in healthy volunteers (W Carey et al. Drugs Exp Clin Res 2002; 28:243), but no well-controlled clinical trials have established that any...

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...

A 0.24% ophthalmic solution of the second-generation H₁-antihistamine cetirizine (Zerviate – Eyevance) is now available by prescription for treatment of ocular itching associated with allergic conjunctivitis in patients ≥2 years old. Oral cetirizine (Zyrtec, and others), which is used for treatment of allergic conjunctivitis and rhinitis, has been available over the counter (OTC) for years.

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.

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.

Olopatadine 0.6% nasal spray (Patanase - Alcon) has been approved by the FDA for treatment of seasonal allergic rhinitis in patients ≥ 12 years old. An H1-antihistamine with mast-cell stabilizing activity, olopatadine is already marketed for treatment of allergic conjunctivitis in a 0.1% solution as Patanol and in a 0.2% solution as Pataday. Azelastine (Astelin), another H1-antihistamine with mast-cell stabilizing activity, has been available for intranasal treatment of allergic rhinitis since 1997.

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.

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.