What is the mechanism of action of cromolyn sodium and in which allergic conditions is it commonly used?

• A. Cromolyn stabilizes mast cell membranes, preventing degranulation and mediator release; used prophylactically in allergic rhinitis and exercise-induced asthma.
• B. Blocks histamine receptors.
• C. Inhibits COX enzymes.
• D. Bronchodilates via beta-adrenergic agonism.

Answer: (A)

Cromolyn sodium works by stabilizing the membranes of mast cells, which prevents their degranulation and the subsequent release of mediators like histamine and leukotrienes. Because it blocks this early release of allergic mediators, its use is best as a preventive measure rather than for acutely reversing symptoms. It’s commonly used prophylactically in conditions such as allergic rhinitis and exercise-induced asthma, often administered as a nasal spray or inhaled formulation to reduce the likelihood of an allergic flare. It is not a histamine receptor blocker, not a COX inhibitor, and not a bronchodilator, so it does not relieve acute bronchospasm or act by reversing established bronchoconstriction.