Cytochrome P450 family 2 subfamily C member 9 (CYP2C9) is involved in the oxidation of xenobiotic and endogenous compounds. It plays a key role in the metabolism of the S-isomer of warfarin. Cytochrome P450 (CYP) participates in the metabolism of drugs. CYP450 enzymes play a key role in the synthesis of cholesterol, steroids, prostacyclins, and thromboxane A2.?They are essential for foreign chemical detoxification.