A pharmaceutical drug is a drug that is used to diagnose, treat or prevent disease. Pharmaceuticals are classified based on the level of control, mode of action, therapeutic effects, biological system affected or route of administration. Some classes of drugs are analgesics, antipyretics, antibiotics, antiseptics, oral contraceptives, tranquilizers, hormone replacements, etc. Drugs can be administered in various dosages in the form of pills, capsules or tablets, and their administration can be parenteral, enteral, topical, intranasal, rectal, etc. Drug discovery, drug development and drug delivery are important areas of research in pharmaceutical science. Biotechnology is a major driver in the discovery of biopharmaceuticals. There has been constant research around the development of novel antibiotics and antibacterials as well as on the use of biological agents for antibacterial therapy. This facilitates better drug design and development. This book is a compilation of chapters that discuss the most vital concepts and emerging trends in the field of pharmacology. From theories to research to practical applications, case studies related to all contemporary topics of relevance to pharmaceuticals have been included in this book. It will help the readers in keeping pace with the rapid changes in this field.