The So-Called COX-3 Isoform

After discovery of a COX-1 variant in some regions of the brain, it was suggested that acetaminophen, a weak inhibitor of COX-1 and COX-2, acts by inhibiting this variant, termed COX-3. Discovered in 2002, encoded by the COX-1 gene and with an intron not retained in COX-1, COX-3 was shown to be inhibited by acetaminophen, phenacetin, metamizole (dipy-rone), antipyrine, and some NSAIDs in rodent experiments. It turned out, however, that results with canine COX-3 were not applicable to mouse 

Data from Warner TD et al. Proc Natl Acad Sci. 1999 96 7563 

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