Metabolites are formed through enzymatic reactions that occur in various phases of metabolism:
Phase I Metabolism: This phase involves the introduction or unmasking of functional groups on the xenobiotic. Reactions include oxidation, reduction, and hydrolysis, generally carried out by enzymes such as the cytochrome P450 family. Phase II Metabolism: This phase involves conjugation reactions where the xenobiotic or its Phase I metabolite is coupled with another substance, such as glucuronic acid, sulfate, or glutathione, to increase its water solubility for excretion.
