Olopatadine hydrochloride (Patanol - Alcon), a propilidinedibenzoxypin derivative, has recently been marketed in a 0.1% ophthalmic solution for prevention of itching due to allergic conjunctivitis in adults and children more than three years old. It is the first drug for this indication that both inhibits mast cell degranulation and is a selective histamine H1 receptor antagonist (NA Sharif et al, J Pharmacol Exp Ther, 278:1252, 1996).

Lodoxamide, a mast cell stabilizer, has been marketed in a 0.1% ophthalmic solution (Alomide - Alcon) for treatment of vernal keratoconjunctivitis.

A 0.05% ophthalmic solution of levocabastine hydrochloride (Livostin - Iolab), a histamine H 1 -receptor antagonist, has been approved by the US Food and Drug Administration for treatment of seasonal allergic conjunctivitis. The new drug is a cyclohexylpiperidine derivative with no structural relationship to any other antihistamine.

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.

Ophthalmic formulations of ketotifen fumarate (Zaditor), pemirolast potassium (Alamast) and nedocromil sodium (Alocril) have recently been approved by the FDA for use in adults and children with itching of the eyes due to allergic conjunctivitis.

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.

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.

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.

Initial treatment of allergic rhinitis (AR) depends on the severity of symptoms and whether they are intermittent or persistent (see Table 1).