Author(s): Shah-Jalal Sarker [[dagger]] 1 , Abu Nayeem Chowdhury 2 , Zahid Hussain 3 , AKM Mosharrof Hossain 4 , Hashem Chowdhury 5
allergic conjunctivitis; efficacy; ketotifen fumarate; olopatadine hydrochloride
Allergic eye disease affects approximately one-fifth of the world'âs population  . The most disabling effects are due to the clinical manifestations, with some patients having seasonal exacerbations of their symptoms, whereas others have symptoms that are present throughout the year  . The number of people affected by allergic conjunctivitis (AC) is increasing day by day along with environmental pollution. Approximately 30% of the US population has some form of allergy  and up to 40% of the US population have experienced ocular symptoms at least once in their lifetime, with a peak of symptoms in the months of June and July  . Similarly, seasonal AC affects 15% of the UK population: in spring when the predominant airborne allergen is tree pollen and in summer when the predominant allergen is grass pollen, or in fall when the predominant allergen is weed pollen  . There are no accurate statistics regarding the incidence of AC in Bangladesh. However, it may vary from 15 to 30%. The predominant allergens in Bangladesh are tree pollen, animal dander, grass pollen and wood pollen, and the main allergy season is spring and summer.
Allergic conjunctivitis is a typical hypersensitivity reaction mediated by IgE in response to environmental antigens  . Mast cells play an important role in the pathogenesis of AC. Binding of specific antigens on mast cells in the conjunctiva leads to mast cell degranulation and the release of histamine and other allergic and inflammatory mediators  . Histamine is the principal mediator, which is responsible for the major signs and symptoms of AC including ocular itching, redness, tearing and lid swelling in ocular allergy. If mast cell activity is not blocked, symptoms such as itching and red eye will continue.
The pharmacotherapy of AC consists of several classes of drugs: H1 receptor blockage, mast cell stabilizers, dual-acting agents, NSAIDS and corticosteroids. Topical histamine H1 receptor antagonists are the primary means of treating ocular allergic disorders due to their rapid treatment of itching and redness. Recently antihistaminic agents with mast cell stabilizing properties have been described. This dual action controls the signs and symptoms during the acute phase (antihistaminic action) and also prevents long-term mast cell degranulation  . Ketotifen fumarate (KF) and olopatadine hydrochloride (OHCL) have dual actions that offer a combination of these two mechanisms [6,7] .
As a combination of mast cell stabilizer and antihistamine, KF has been used for treatment of AC with some minor adverse effects and OHCL is a relatively newer drug with the same mode of action but a better safety profile. Olopatadine is a potent antihistamine with high affinity for H1 receptors. It is the only compound that inhibited the release of histamine from human conjunctival mast cells without causing degranulation. However, KF showed significant membrane disruption of mast cells and corneal epithelial cells, indicating degranulation potential  . A study based on cultured conjunctival cells of...