Welcome to the second volume of "Medicinal Chemistry Theory," a comprehensive exploration of the principles and practices that underpin the fascinating field of medicinal chemistry. This volume, Medicinal Chemistry Theory-II, builds upon the foundation laid in the first volume and delves deeper into the intricate world of drug discovery and design. When chemistry, biology, and pharmacology come together, you get medicinal chemistry, a vibrant and interdisciplinary field. Its main purpose is to create new medicines that can be used to treat illnesses and boost people's health. In this volume, we continue our investigation of the molecular interactions that determine the pharmacological activity of substances and its application in drug creation. The discovery of potentially life-saving medications has been greatly aided by the insights gained from medicinal chemistry studies. The work of medicinal chemists is essential in the development of new therapeutics, from small molecule inhibitors to biologics and gene therapies. Structure of the Book: Medicinal Chemistry Theory-II comprises several chapters, each dedicated to a specific aspect of the drug discovery process. We begin with a recap of key concepts from the first volume, providing a seamless transition for readers who may be new to this book series. However, each chapter can also be read independently for those seeking indepth knowledge on particular topics. The chapters in this volume cover a wide range of subjects, including: 1. Drug Metabolism and Pharmacokinetics: Understanding how drugs are metabolized and how their concentration in the body changes over time. 2. Structure-Activity Relationship (SAR) Studies: Exploring the relationship between the chemical structure of compounds and their biological activity. 3. Drug Design Strategies: Examining various approaches employed by medicinal chemists to design novel drugs with enhanced potency and selectivity. 4. Enzyme Inhibitors: Investigating the design and mechanisms of enzyme inhibitors as potential therapeutics