25.2.1 What Is Cromolyn?

Cromolyn and cromolyn-like products, such as disodium cromoglycate (DSCG), are inspired by the mast cell-stabilizing properties of Khellin, derived from a plant called Ammi visnaga. It is spasmolytic and its use dates back to ancient Egyptian times. You may see various names for cromolyn-type products such as DSCG, cromolyn sodium, sodium cromoglycate, disodium 4,4′-dioxo-5, 5′-(2-hydroxytrimethylenedioxy)-di(4H-chromene-2-carboxylate).

Although the mechanism of cromolyn’s effect is somewhat debated, it is thought to stabilize mast cells by altering the function of cellular chloride channels. This prevents influx of calcium into the cytoplasm from the extracellular space, and ultimately stops degranulation of the sensitized mast cell, which would typically occur following cross-linking of mast cell-bound allergen-specific immunoglobulin E (IgE) that has come into contact with its antigen. If the mast cell does not degranulate, histamine is not released. In addition, if calcium influx is stopped, synthesis of lipid mediators such as prostaglandins and leukotrienes is affected, along with other cytokines and chemokines.

First-generation mast cell stabilizers DSCG and nedocromil sodium prevent mast cell degranulation. Later generation mast cell-stabilizing products such as olopatadine also contain antihistamines, giving them an added benefit in the treatment of allergic disease. Various cromolyn-like products also have apparent effects on eosinophils, macrophages, monocytes, that increase their anti-allergy properties. Chromolyn-type products work on both the early- and late-phase allergic responses.