Mast Cell Stabilizers in the Treatment of Allergic Rhinitis

Allergic rhinitis (AR) is caused by an immediate type hypersensitivity reaction in sensitized subjects after exposure to airborn allergens. The interaction of the allergen with a specific IgE antibody attached to the nasal mast cells leads to the local release of vasoactive and inflammatory mediators such as histamine, leukotriene C4 and prostaglandin D2. These mediators cause the nasal allergic symptoms complex of rhinorrhea, nasal obstruction, nasal itching and sneezing, which improve spontaneously or with treatment. Cromolyn sodium and nedocromil sodium are often termed ‘antiallergic drugs’, which are defined here as drugs capable of inhibiting both the early-phase response to challenge and chronic allergic inflammation. They act at the cell membrane levels. Intranasal and ocular formulations of cromones, such as cromoglycate, are available without medical prescription in many countries. Sodium cromoglycate or nedocromil have a good safety profile. They reduce the symptoms of AR, and should be used profilactically, but limited efficacy and the need for frequent dosing are disadvantages.