Aspirin - does it inhibit enzyme of thromboxane? This is a diagram a friend showed me about the drug aspirin, where we were arguing which enzyme it prevents. ![enter image description here]( Aspirin is known to inhibit the production of prostaglandins. However, it also serves fit as a purpose to inhibit production of thromboxane. My question is, does the drug inhibit enzyme a to prevent the production of both thromboxane and prostaglandins, or only enzyme B?

Aspirin and some other NSAIDs inhibit cyclooxygenase which is the first enzyme in the prostaglandin/thromboxane biosynthesis pathway if you consider first substance is arachidonic acid (a fatty acid). Generally, arachidonic acid is present in the form of a phospholipid, and if you consider that in the pathway, substance-Y is arachidonic acid and enzyme-A is cyclooxygenase.

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> ![enter image description here]( **From:** Heckmann, Lars-Henrik, et al. "Outlining eicosanoid biosynthesis in the crustacean Daphnia." _Front. Zool_ 5.11 (2008).