Arachidonoyl-
2'-
fluoroethylamide (2-
fluoro AEA) is an analog of anandamide in which the alcohol of the ethanolamide group has been removed and replaced with a fluorine atom. This substitution adds considerably increased binding affinity for the CB
1 receptor (K
is = 26.7 and 908 nM for CB
1 and CB
2, respectively). It also contributes additional selectivity, in that binding to CB
2 is decreased relative to AEA.
1 However, the
in vivo activity of 2-
fluoro AEA is enhanced much less than the binding affinity, because the analog remains a good substrate for FAAH and is rapidly hydrolyzed by this enzyme.