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.

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.

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.

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.

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.

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.

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.

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 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.

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.