Arachidonic acid is converted by microsomal CYP450 enzymes to a variety of epoxides, ω-1 and ω-hydroxylated compounds via what is known as the epoxidase pathway. PPOH is a selective inhibitor of the epoxygenation reactions catalyzed by specific CYP450 isozymes. PPOH inhibits the formation of arachidonate 11,12 epoxides by CYP4A2 and CYP4A3 enzymes with an IC50 of 9 μM, but has effect on the formation of 20-HETE, the ω-hydroxylation product of CYP4A1.