It has been reported that anandamide (AEA) can be used directly by cyclooxygenase-2 and specific prostaglandin H2 (PGH2) isomerases to produce ethanolamide congeners of the classical PGs, including PGF2α.¹ PGF2α ethanolamide has also been reported to be biosynthesized by this mechanism when AEA was infused into the lung and liver of fatty acid amide hydrolase-deficient mice.² However, the accumulation of AEA can also lead to isoprostane-type peroxidative decomposition. 8-iso PGF2α ethanolamide is a standard that allows one to distinguish these non-enzymatic decomposition products from “prostamides” that could be of enzymatic origin.