Which statement correctly describes aspirin's mechanism for its analgesic and anti-inflammatory effects?

Which statement correctly describes aspirin's mechanism for its analgesic and anti-inflammatory effects?

• A. Irreversible inhibition of COX-1 and COX-2
• B. Reversible inhibition of COX-1
• C. Activation of Prostaglandin Synthesis
• D. Inhibition of Lipoxygenase Pathway

Answer: (A)

Aspirin works by blocking prostaglandin production through irreversible acetylation of the cyclooxygenase enzymes. It covalently modifies COX-1 and COX-2 at their active sites, permanently inactivating them in the cells it touches. This prevents arachidonic acid from being converted to prostaglandin H2, the precursor of inflammatory prostaglandins like PGE2 and others involved in pain and swelling. Because the inhibition is irreversible, new COX enzymes must be synthesized to restore function; in platelets, which lack a nucleus, this effect lasts for the platelet’s lifetime, contributing to aspirin’s antiplatelet action as well. This mechanism explains why aspirin provides analgesia and anti-inflammatory effects. Other options don’t fit: reversible inhibition of COX-1 would resemble other NSAIDs but not aspirin’s signature action; activation of prostaglandin synthesis would worsen inflammation and pain; and inhibition of the lipoxygenase pathway affects leukotriene production rather than the prostaglandin pathway most directly tied to aspirin’s analgesic and anti-inflammatory effects.

Aspirin works by blocking prostaglandin production through irreversible acetylation of the cyclooxygenase enzymes. It covalently modifies COX-1 and COX-2 at their active sites, permanently inactivating them in the cells it touches. This prevents arachidonic acid from being converted to prostaglandin H2, the precursor of inflammatory prostaglandins like PGE2 and others involved in pain and swelling. Because the inhibition is irreversible, new COX enzymes must be synthesized to restore function; in platelets, which lack a nucleus, this effect lasts for the platelet’s lifetime, contributing to aspirin’s antiplatelet action as well. This mechanism explains why aspirin provides analgesia and anti-inflammatory effects.

Other options don’t fit: reversible inhibition of COX-1 would resemble other NSAIDs but not aspirin’s signature action; activation of prostaglandin synthesis would worsen inflammation and pain; and inhibition of the lipoxygenase pathway affects leukotriene production rather than the prostaglandin pathway most directly tied to aspirin’s analgesic and anti-inflammatory effects.