Cyclooxygenase 1
Also known as: COX-1, COX1, PTGS1
Constitutive enzyme that produces prostaglandins with protective functions: maintains the gastric mucosa, regulates platelet aggregation (thromboxane A2) and renal flow.
COX-1 inhibition by NSAIDs and aspirin explains the gastrotoxic effects (ulcer, bleeding) and, with aspirin, the antiplatelet effect. It is the target of NSAID + anticoagulant/antiplatelet interactions.
Substrates: arachidonic acid (yields PGE2, PGI2, thromboxane A2).
Inhibitors: aspirin (irreversible, low doses), diclofenac, ibuprofen, naproxen, ketorolac, indomethacin.
Inducers: not applicable (no clinically relevant inducers).
COX-1 inhibition is the mechanism of additive bleeding risk when NSAIDs/aspirin are combined with oral anticoagulants or antiplatelets.
DailyMed/FDA (NIH/NLM) — approved labels (aspirin, NSAIDs); EMC-UK (MHRA) — SmPC
