drug metabolism phase I drug metabolism phase I by Cytochrome P450 Drug metabolism phase I by Cytochrome P450 is a subtype of drug metabolism phase I: A process that is biotransformed by cytochrome P450 (CYP) superfamily . NCIT:C91423 PMID:16584116 https://reactome.org/PathwayBrowser/#/R-HSA-211945&SEL=R-HSA-211981&PATH=R-HSA-1430728,R-HSA-211859