PF-04457845 is a potent and exquisitely selective inhibitor of the enzyme fatty acid amide hydrolase (FAAH), with an IC50 of 7.2nM, and both analgesic and antiinflammatory effects in animal studies comparable to naproxen. It has been well tolerated in human trials even at high dose ranges with no evidence for cognitive dysfunction, and has completed Phase II clinical trials for the treatment of osteoarthritis. From Wikipedia.