[4,8,12,13] Six major classes of CYP isoenzymes that play a vital role in drug biotransformation are CYP 1A2, CYP 2C19, CYP 2C9, CYP 2D6, CYP 2E1, and CYP 3A4.
This is owing to the inhibition of the metabolic enzyme CYP 2C9 by sulfonylureas.
Allium is an active compound in garlic and is directly implicated in the induction of CYP 3A4, CYP 2C9, and CYP 2C19 isoenzymes.
The medication is metabolized primarily by oxidation through cytochrome P (CYP) 450: CYP2D6 (primary), CYP 3A4/5, CYP 2C19, CYP 2C9
, CYP2A6, CYP2C8, and CYP2B6 with subsequent glucuronidation.
In humans, (S)-warfarin is metabolized almost exclusively by CYP 2C9
to its inactive form, (S)-7-hydroxywarfarin, while (R)-warfarin is metabolized by multiple CYPs such as CYP1A1 and CYP3A4 (Kaminsky and Zhang 1997).
Multiple regression analysis for modeling warfarin daily dose requirements based on age, sex, weight, VKORC1 (-1639G>A), and CYP 2C9
Assessment of the gene coding for CYP 2C9
can help physicians tailor warfarin doses to prevent bleeding episodes in patients with genetic propensities for higher-than-average responsiveness to the drug.
(4) Fluvoxamine, fluoxetine, and paroxetine inhibit CYP 2C9
, through which warfarin and some other drugs with a narrow therapeutic index are metabolized.