Cromolyn sodium prevents mast cell degranulation in bronchial asthma prophylaxis. Its cellular mechanism involves:

• A Competitive antagonism at H1 histamine receptors on bronchial smooth muscle
• B Inhibition of chloride channels in mast cell membrane, preventing membrane depolarization triggered by antigen-IgE cross-linking ✓
• C Blocking leukotriene receptor (CysLT1) to prevent bronchoconstriction
• D Inhibiting phospholipase A2, reducing arachidonic acid availability

Explanation

Cromolyn (sodium cromoglicate) inhibits calcium-sensitive chloride channels in the mast cell membrane. Antigen cross-linking of IgE on mast cells triggers calcium influx, and chloride channel opening is required for the subsequent membrane events leading to vesicle fusion and degranulation. By blocking chloride channel activation, cromolyn prevents the cascade of degranulation and release of histamine, leukotrienes, and other mediators. It has no direct bronchodilator or antihistamine action — it is purely prophylactic and must be used before allergen exposure.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.