Anti allergic Drugs: Topical And Systemic

Ocular allergic represents a variety of problems that are primarily type-1 hypersensitivity reactions (IgE mediated) which results in histamine release causing variety of uncomfortablesymptoms and sometime life-threatening complications.

The antiallergic drugs come in form of topical mass cell stabilizers, topical and oral antihistamines, topical and systemic NSAIDs, topical steroids and topical immunesuppressors.

Examples of ophthalmic antiallergic drugs include the following;

CROMOLYN SODIUM (SODIUM CROMOGLYCATE): It is a topical mast cell stabilizer indicated in the treatment of allergic ocular disorders including vernal keratitis, allergic keratoconjunctivitis, giant papillary conjunctivitis and vernal keratoconjunctivitis. It inhibits the degranulation of sensitized mast cells and basophils which occur after exposure to specific antigens thus inhibiting the release of histamine and SRS-A (Slow reacting substance of anaphylaxis) from mast cells. Cromolyn sodium is available as 2% and 4% topical ophthalmic solution and patient is advised to instill one to two drops four to six times daily at regular intervals till the desired effect is obtained.

LODOXAMIDE: It is the most potent topical mast cell inhibitor and it prevents histamine release from mast cells during immediate hypersensitivity reactions. Lodoxamide is highly effective in treatment of vernal and atopic keratoconjunctivitis (VKC and AKC) and in giant papillary conjunctivitis. It is available as 0.1% ophthalmic suspension with usual dose of one to two drops four times daily throughout the year.

NEDOCROMIL: It is effective in VKC, SAC and GPC. Nedocromal prevents chemotaxic and inflammatory mediator release from mast cells, monocytes, macrophages and granulocytes. It is available as 1% ophthalmic solution and patient is advised to instill one to two drops four times daily.

KETOTIFEN: It is indicated for the treatment of allergic conjunctivitis of diverse etiology. Ketotifen is available as 0.025% topical solution in 5ml and 7ml packs. Instill one drop every 8-12 hours.

OLPATADINE (PATANOL): Olopatadine hydrochloride has both mast cell stabilization effect and an antihistaminic effect. It is indicated for the treatment of allergic conjunctivitis of diverse etiology Olopatadine is available as 0.1% ophthalmic solution in 5ml vial. The patient is advised to instill one to two drops three to four times daily every six to eight hours.

LEVOCABASTINE (LIVOSTIN): Levocabastine hydrochloride is indicated in treatment of seasonal allergic conjunctivitis. It provides relief within minutes and block histamine, the primary mediatory response to allergy. It is available as 0.05% ophthalmic suspension. For dosage, instill one drop four times daily, treatment may be continued up to two weeks.

EMEDASTINE DIFUMARATE (EMADINE): It is an antihistamine indicated in the treatment of allergic conjunctivitis. It is available as 0.05% ophthalmic solution. Recommended dosage is to instill one drop four times daily.

NAPHAZOLINE HYDROCHLORIDE: It acts as a decongestant used as topical vasoconstrictor to soothe, refresh, moisturize and remove redness due to mild ocular allergic disorders in minor eye irritation. Naphazoline is available as 0.012-0.1% ophthalmic solution. Usual dosage is to instill one to two drops every two to four hours.

TOPICAL NSAIDS: the two common examples of topical NSAIDs used in eye allergic conditions are; Suprofen and Ketorolac. They are effective in managing the signs and symptoms of giant papillary conjunctivitis and vernal kreatoconjunctivitis. Usual dosage is to instill one to two drops three times daily for four to six weeks.

TOPICAL STEROIDS: Common examples include; Loteprednol 0.5% solution, Rimexolone 1.0% solution and Fluorometholone 0.3% solution. They effectively suppresses inflammation in allergic conjunctivitis. Usual dosage is to instill one to two drops three to four times daily.

TOPICAL IMMUNOSUPPRESSORS: The common example is cyclosporine which is available as 2.0% ophthalmic solution and recommended dosage is to instill one drop four times daily.

ORAL ANTIHISTAMINE: Common examples are Levocetrizine (5mg tablet), Desloratadine (5mg tablet) and Fexofenadine (60 and 12mg tablet). Levocetrizine and Desloratadine are indicated in allergic conjunctivitis and the recommended dosage is to take 5mg oral tablet once daily. Fexofenadine is indicated in vernal keratoconjunctivitis and seasonal allergic conjunctivitis. Recommended dosage is 60mg twice daily or 120mg once daily for fourteen to twenty one days till desired response is obtained.