Which mediator is inhibited by Corticosteroids but NOT by NSAIDs?

• A. Leukotrienes
• B. Prostaglandins
• C. Thromboxanes
• D. Prostacyclines

Answer: (A)

The main concept is how these drugs block different parts of the arachidonic acid pathway. Corticosteroids stop the release of arachidonic acid by inhibiting phospholipase A2 (via induction of lipocortin/annexin-1), so they reduce production of all downstream eicosanoids, including leukotrienes. NSAIDs, however, inhibit cyclooxygenase enzymes (COX-1 and COX-2), blocking the conversion of arachidonic acid into prostaglandins, thromboxanes, and prostacyclins, but they do not affect the lipoxygenase pathway that makes leukotrienes. Since leukotrienes rely on the lipoxygenase pathway and are not suppressed by NSAIDs, they are specifically inhibited by corticosteroids but not by NSAIDs. This distinction helps explain why steroids are effective in inflammatory and bronchoconstrictive processes driven by leukotrienes, whereas NSAIDs do not dampen leukotriene production.