Sodium cromoglycate fails to provide benefit when taken by a patient during an ongoing acute asthmatic attack. The reason is:

• A It is rapidly degraded by airway esterases before reaching target cells
• B It has negligible bronchodilator activity and acts only by preventing mast cell degranulation ✓
• C It antagonises beta-adrenergic receptors at therapeutic doses
• D It downregulates glucocorticoid receptors, blunting steroid rescue therapy

Explanation

Cromoglycate is a prophylactic agent that stabilises mast cells and blocks antigen-triggered mediator release; it produces no bronchodilation and does nothing once mediators have already been released. Hence it must be taken regularly before exposure and is useless in an established attack. Options A, C and D describe mechanisms it simply does not possess. This prophylaxis-only profile is the classic examination point for this drug.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.