What is the mechanism of action (MOA) of intranasal cromolyn?

Intranasal cromolyn acts as a mast cell stabilizer, which is the correct answer. Its primary mechanism of action involves preventing the degranulation of mast cells, which are a type of immune cell that releases histamine and other inflammatory mediators during allergic reactions. By stabilizing these cells, intranasal cromolyn effectively reduces the release of histamines and other substances that contribute to allergy symptoms, such as nasal congestion, sneezing, and itching.

In contrast, antihistamines work by blocking the effects of histamine at its receptors, which temporarily alleviates symptoms but does not prevent the initial release of histamine from mast cells. Corticosteroids, on the other hand, reduce inflammation by suppressing multiple inflammatory mediators; while effective for persistent symptoms, their action is different from that of mast cell stabilizers. Lastly, leukotriene receptor antagonists block the action of leukotrienes—another type of inflammatory mediator—instead of stabilizing mast cells.

Thus, intranasal cromolyn’s role as a mast cell stabilizer specifically positions it to prevent the allergic response at its source, making it effective for managing allergic rhinitis symptoms.