PF-750 is a potent, time-dependent, irreversible FAAH inhibitor with IC50 values 0.6 and 0.016 μM when preincubated with recombinant human FAAH for 5 and 60 minutes, respectively. Fatty acid amide hydrolase (FAAH) is the enzyme responsible for hydrolysis and inactivation of fatty acid amides including anandamide and oleamide. Activity-based profiling of various human and murine tissue proteome samples revealed that PF-750 is highly selective for FAAH relative to other serine hydrolases, showing no discernable off-site activity up to 500 μM. PF-750 shows 10-fold better potency than URB597 (Sigma# U4133) after 30 min preincubation. PF-750 is highly selective on FAAH. Even at as high as 500 μM, it had no interactions with many tested enzymes, but URB597 and other known FAAH inhibitors did not perform well at low concentraction (100 μM).