Drug metabolites are chemical substances formed after drugs undergo biotransformation in the body, involving a wide range of enzyme systems, mainly including the cytochrome P450 family, glucuronosyltransferases, sulfotransferases, etc. These metabolites are most abundant in the liver but can also be formed in tissues such as the intestine, kidneys, and lungs. They participate in various biological reactions and signaling pathways, such as detoxification, excretion, and pharmacological modulation. The specific expression of genes and individual genetic variations significantly affect the rate of drug metabolism and the types of metabolites formed, thereby affecting drug efficacy and toxicity. Understanding these metabolic pathways and gene expression patterns is crucial for personalized medicine and reducing adverse drug reactions.