Albendazole monooxygenase () is an enzyme that catalyzes the chemical reaction
The four substrates of this enzyme are albendazole, reduced nicotinamide adenine dinucleotide phosphate (NADPH), oxygen and a proton. Its products are ricobendazole (albendazole S-oxide), oxidised NADP<sup>+</sup>, and water.
This enzyme is coded by the gene for CYP3A4 and is a flavin-containing monooxygenase that uses molecular oxygen as oxidant and incorporates one of its atoms into the starting material. 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, flavin adenine dinucleotide.
A similar oxidation is carried out by , albendazole monooxygenase (sulfoxide-forming)