Author: Dr. Surya Prakash Gupta
Volume: 01
First Online: 31 August 2024
Pages: 28-48
DOI:

Drug metabolism is a critical process that modifies pharmaceutical substances to facilitate their elimination from the body. It primarily occurs in the liver and involves two main phases: Phase I and Phase II reactions. Phase I reactions, also known as functionalization reactions, introduce or expose functional groups through oxidation, reduction, or hydrolysis. Enzymes such as cytochrome P450s play a pivotal role in these reactions, often resulting in the production of more polar and reactive metabolites. Phase II reactions, or conjugation reactions, involve the coupling of these metabolites with endogenous substrates like glucuronic acid, sulfate, or glutathione, leading to highly water-soluble compounds that are easier to excrete. Several factors influence drug metabolism, including genetic polymorphisms, age, sex, diet, and disease states. Genetic variations can lead to differences in enzyme activity, affecting how individuals metabolize certain drugs. Age and sex can also impact metabolic rates, with infants and the elderly often metabolizing drugs more slowly, while men and women may have different enzyme expression levels. Diet, particularly the intake of certain foods and beverages, can induce or inhibit metabolic enzymes. Additionally, liver diseases or other health conditions can impair metabolism, altering drug efficacy and safety. Stereochemistry, the spatial arrangement of atoms in a drug molecule, is another crucial factor. Enantiomers, or mirrorimage isomers, can be metabolized differently by the body’s enzymes, leading to variations in pharmacological activity and side effects. Understanding these principles and factors is essential for predicting drug behavior, personalizing treatments, and minimizing adverse reactions.