Many non-steroidal anti-inflammatory drugs (NSAIDs) are potent but non-selective inhibitors of both COX-1 and COX-2 in humans. CAY10404 is one of the most selective inhibitors of COX-2 which has been reported to date, with a selectivity index (SI; SI = IC50 COX-1/IC50 COX-2) of >500,000. (The COX-1 IC50 is >500 mM, and COX-2 IC50 is <1 nM.) As a reference point, the SI of celecoxib is about 400. Thus, CAY10404 has an SI which is several logs greater than the first generation of selective COX-2 inhibitors, and is comparable to the SI of second generation selective COX-2 inhibitors, such as valdecoxib and etoricoxib.
