cytochrome P450 2C9 isozyme (CYP2C9). The R-isomer is metabolized by cytochrome P450 1A2 and
3A4 isozymes. Drugs that induce or inhibit these enzyme systems have the ability to alter warfarin
metabolism and to decrease or increase the INR, respectively. Most notable are interacting substances that affect CYP2C9, given the increased potency of the S-isomer.