Trimethoprim 3-oxide (Trimethoprim 3-N-oxide) is the primary metabolite of trimethoprim. In Vitro Trimethoprim 3-oxide is the primary metabolite of trimethoprim. Trimethoprim 3-oxide (3-NO-TMP) is converted from trimethoprim by CYP1A1 and CYP1B1 with highest rates in human liver microsomes (HLMs). The CYP1A inhibitor α-Naphthoflavone inhibits Trimethoprim 3-oxide formation, however, other competitive P450 inhibitors has no obvious inhibition on the formation. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid