Although both rats and humans metabolized CDEPA to DEA (Figures 8 and 9, respectively), the human liver microsomal arylamidase was more active toward either CDEPA or CMEPA than the rat liver microsomal arylamidase.
CYP2B6 metabolized both alachlor and butachlor to CDEPA, acetochlor to CMEPA, and metolachlor to an unknown metabolite.
It could be argued that the presence of the arylamidase in microsomes effectively removes CDEPA or CMEPA as quickly as it is formed, resulting in apparently low steady-state levels of CDEPA or CMEPA product formation.
For acetochlor, the rate of metabolism to CMEPA by human liver microsomes is approximately one-third the rate observed in rat liver microsomes.
The greater metabolism of acetochlor to CMEPA as compared to the metabolism of alachlor to CDEPA suggests that the methyethyl phenyl group is more readily metabolized than the diethyl phenol group in these pesticides.