11-hydroxy THC ) which is then converted to inactive metabolites and excreted in urine/stool. That site mentions CYP3A3, CYP3A4, CYP2C9, and CYP2C6. In biochemistry, a substrate is a molecule upon which an enzyme acts. Wikipedia lists THC as a minor substrate of CYP3A4 . THC is also a substrate of CYP2C19