In the spirit of understanding how drugs work, this textbook explores the fundamental physicochemical attributes and processes important for understanding how a drug, usually in the form of a crystal, is transformed into a usable product that is administered to a patient to reach its pharmacological target and then leave the body. This is the discipline of physical pharmacy—the study of the physical and chemical properties of drugs and their dosage forms. When integrated with other critical knowledge of how drugs work, such as their pharmacologic effects, physical pharmacy forms part of the scientific foundation for the clinical sciences and, therefore, for clinical practice. A distinguishing feature of physical pharmacy is that, unlike pharmacology, which is learned to different degrees by other healthcare practitioners, physical pharmacy is a body of knowledge unique to the education of student pharmacists, for whom this textbook is written. It provides the physicochemical basis for rational formulation, manufacturing, compounding, drug delivery, product selection, and product usage. Therefore, knowledge of physical pharmacy enables the pharmacist to understand and explain how drugs work, in a manner and to an extent that is unparalleled by any other healthcare practitioner. In other words, it is a part of the body of knowledge that equips pharmacists with unique perspectives and insights in the provision of pharmaceutical care.
Chapters in this third edition of Applied Physical Pharmacy retain features of previous editions, including the Learning Objectives and Practice Problems of the first edition and the Key Points and Clinical Questions introduced in the second edition. As part of a continuing effort to focus the textbook on the education of the student pharmacist, more clinical questions were added and more graduate level material was moved to chapter appendices. In addition, chapters were edited for clarity and many tables in the chapters were updated with more current products and excipients.
The textbook begins with a review of the key biopharmaceutics concepts of drug liberation, absorption, distribution, metabolism, and excretion. These concepts and others set the framework for subsequent chapters that describe physicochemical properties and processes related to the fate of the drug. These include states of matter (Chapter 2), solutions (Chapter 3), ionization (Chapter 4), dissolution and partitioning (Chapter 5), mass transport (Chapter 6), and complexation and protein binding (Chapter 7). Concepts in these chapters are important not only for understanding a drug’s fate in the body but also for providing the scientific basis for rational drug formulation. Other physical pharmacy topics important to drug formulation and usage are discussed in the three chapters that follow, which describe dispersed systems (Chapter 8), interfacial phenomena (Chapter 9), and rheology (Chapter 10). The textbook concludes with an overview of the principles of kinetics (Chapter 11) that are important for understanding the rates at which many of the processes discussed in previous chapters occur.
We continue to be grateful to all of the contributing authors who shared with us their expertise in important physical pharmacy knowledge and skills. Thank you also to all of the McGraw-Hill editors, especially to Michael Weitz who provided the guidance for this edition. We also thank our pharmacy students who continuously inspire us to improve our craft of teaching, and our families for their continuing love, support, and patience. Finally, we mourn the passing in February of 2018 of Beverly J. Sandmann, who was co-editor of the first edition of Applied Physical Pharmacy and was a major contributor to each edition. Beverly was a dedicated pharmacy educator and professional, whose practice included retail, hospital, and compounding pharmacy. Her contribution to the field of pharmacy and her inspiration of student pharmacists are immeasurable and enduring, and it is to her that we dedicate this edition.