Pharmacology · single question
What is the mechanism of action of dexamethasone?
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Correct answer: D. Agonist of glucocorticoid receptors
- A. COX inhibition is the mechanism of NSAIDs (aspirin, ibuprofen) — corticosteroids work upstream, inhibiting phospholipase A2 (preventing arachidonic acid release for both COX and lipoxygenase pathways).
- B. Mineralocorticoid receptor antagonism is the mechanism of spironolactone — not dexamethasone (which acts on glucocorticoid receptors).
- C. Phosphodiesterase inhibition is the mechanism of methylxanthines (theophylline) and certain drugs like sildenafil — not corticosteroids.
- D. Dexamethasone (and all corticosteroids) are AGONISTS of GLUCOCORTICOID RECEPTORS — they bind to intracellular glucocorticoid receptors (nuclear receptors), which then translocate to the nucleus and regulate gene transcription. This leads to: anti-inflammatory effects (reduced cytokine production, reduced prostaglandin synthesis via lipocortin inhibition of phospholipase A2), immunosuppression, and metabolic effects.