CYP2E1 and tuberculosis: Moreover, NAT2 mediates isoniazid biotransformation to form acetylhydrazine, which then undergoes oxidization by CYP2E1 to form a hepatotoxic substance32, but there is little evidence to implicate these enzymes in the metabolism of other anti-TB drugs such as pyrazinamide, which account for approximately 60% of ATDH33.