In enzymology, an albendazole monooxygenase (EC 1.14.13.32) is an enzyme that catalyzes the chemical reaction

albendazole + NADPH + H⁺ + O₂ ${\displaystyle \rightleftharpoons }$ albendazole S-oxide + NADP⁺ + H₂O

The four substrates of this enzyme are albendazole, NADPH, H⁺, and O₂, whereas its three products are albendazole S-oxide, NADP⁺, and H₂O.

This enzyme is coded by the gene for CYP3A4^[1][2] and belongs to the family of oxidoreductases, specifically those acting on paired donors, with O₂ as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O₂ with NADH or NADPH as one donor, and incorporation of one atom of oxygen into the other donor. The systematic name of this enzyme class is albendazole,NADPH:oxygen oxidoreductase (sulfoxide-forming). Other names in common use include albendazole oxidase, and albendazole sulfoxidase. It employs one cofactor, FAD.