The choice of drugs for treatment of allergic rhinitis depends on the severity of symptoms and whether they are intermittent or persistent (see Table 1).

View the Comparison Table: Some Oral Drugs for Allergic Rhinitis

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 years.

Patients with seasonal allergies often experience nasal itching and congestion, sneezing, rhinorrhea, and itchy, watery eyes. Oral, intranasal, and ophthalmic preparations are widely available over the counter (OTC) for relief of symptoms. Prescription products for management of allergic rhinitis and allergic conjunctivitis are reviewed separately.

Allergic rhinitis can be classified as seasonal, perennial, or episodic. It is often associated with allergic conjunctivitis, rhinosinusitis, and asthma.

H₁-ANTIHISTAMINES — Oral – Oral second-generation H₁-antihistamines are the preferred first-line treatment for relief of the itching, sneezing, and rhinorrhea that characterize mild-to-moderate allergic rhinitis. They are less effective for nasal congestion.

View the Comparison Table: Some Oral Drugs for Allergic Rhinitis

The use of drugs to prevent and control symptoms of allergic disorders can be optimized when patients avoid exposure to specific allergens and/or environmental conditions that trigger or worsen their symptoms.

The FDA has approved a nasal spray fixed-dose combination (Dymista – Meda) of the H₁-antihistamine azelastine (Astelin, Astepro, and generics) and the corticosteroid fluticasone propionate (Flonase, and generics) for treatment of seasonal allergic rhinitis (SAR) in patients ≥12 years old who need both medications for symptomatic relief. It is the first nasal spray to be approved in the US that contains both an H₁-antihistamine and a corticosteroid.

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.

Alcaftadine (Lastacaft – Allergan), an ophthalmic H₁-antihistamine, has been approved by the FDA for prevention of itching associated with allergic conjunctivitis in patients > 2 years old.

Bepotastine besilate 1.5% ophthalmic solution (Bepreve - ISTA Pharmaceuticals), an H₁-antihistamine, has been approved by the FDA for topical treatment of itching associated with allergic conjunctivitis in patients ≥2 years old. Bepotastine was first developed in an oral systemic formulation and has been used as such for treatment of allergic rhinitis in Japan.

Allergic rhinitis, allergic conjunctivitis, atopic dermatitis, urticaria, anaphylaxis and asthma (not included here; reviewed in Treatment Guidelines 2008; 6:83) are prevalent worldwide, especially in industrialized countries. Pharmacologic treatment of these disorders continues to improve in efficacy and safety. In addition to using drugs to prevent and control these allergic diseases, patients should be instructed to avoid, if possible, specific allergens and/or environmental conditions that trigger or worsen their symptoms. Allergen-specific immunotherapy may be useful for treatment of allergic rhinitis and allergic conjunctivitis, and in preventing severe insect venom-triggered reactions.

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.

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.

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.

Montelukast (Singulair - Merck) is an oral cysteinyl leukotriene D₄ receptor antagonist originally marketed for treatment of asthma. It was approved by the FDA in 2003 for treatment of seasonal allergic rhinitis and recently for use in perennial allergic rhinitis in adults and children ≥ 6 months old. Intranasal corticosteroids have generally been considered the most effective drugs available for prevention and treatment of allergic rhinitis.

Epinastine HCl, an H₁-receptor antagonist and mast cell stabilizer, has been approved by the FDA for use in a 0.05% ophthalmic solution (Elestat - Allergan/Inspire) for prevention of itching associated with allergic conjunctivitis. The drug is available orally in Europe and Asia.

The ability of grapefruit juice to increase serum concentrations of drugs was first discovered during a study of the effect of ethanol on felodipine (Plendil) pharmacokinetics. Double-strength grapefruit juice used to disguise the taste of ethanol resulted in higher than expected serum concentrations of felodipine (DG Bailey et al, Clin Invest Med 1989; 12:357).

Changes caused by one drug in the absorption, distribution, metabolism or excretion of another may lead to a pharmacokinetic adverse drug interaction (DN Juurlink et al, JAMA 2003; 289:1652). Additive drug interactions, such as vasodilation caused by both sildenafil (Viagra) and nitrates, can also have adverse effects.

Montelukast (Singulair - Merck), a leukotriene receptor antagonist already marketed for asthma (Treatment Guidelines from The Medical Letter 2002; 1:11), has been approved by the FDA for treatment of seasonal allergic rhinitis in adults and children more than 2 years old.

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.

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.

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.

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.

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."