In Vitro Drug Release Testing and In Vivo/In Vitro Correlation for Long Acting Implants and Injections

Abstract

evolving complexity of human therapeutics requires the development of novel drug delivery systems. This book encapsulates in a single volume the concepts essential for understanding the science and technology associated with the research and development of long acting injections and implants. It provides a comprehensive overview of the scientifi c and regulatory challenges associated with these delivery systems. Critical contributions to this area are the array of formulations that make up the spectrum of long acting injections and implant dosage forms. These include microspheres, liposomes, in situ forming depots, suspensions, implants, lipophilic solutions, and osmotic implants. Such formulations have the potential to maintain therapeutic drug concentrations for durations from days to months, can be engineered to maintain characteristics such as zero-order or pulsatile drug release, and, in some cases (e.g., liposomes) can provide targeted drug delivery to the site of action. These attributes lead to increased patient compliance and convenience, reduced fl uctuations in plasma profi les, and reduced plasma concentrations making it possible to administer higher drug concentrations to the site of action while reducing the overall dose. Thus, unwanted side effects can be minimized or reduced. In addition, long acting injections and implants can provide a means for the delivery of drugs that are subject to degradation in the harsh environment of the gastrointestinal tract, that undergo extensive fi rst pass metabolism, or that exhibit poor bioavailability when such molecules are orally administered. Long Acting Injections and Implants begins with chapters that provide basic concepts explained in a simple, clear, and concise manner. In subsequent chapters additional material, expansions on the basic scientifi c concepts underpinning research and development of such dosage forms, and examples of technological developments in this area are comprehensively reviewed and discussed. The introductory chapter provides a brief description of the types of systems and major areas of current application and research. The Historical Overview chapter provides a chronological overview of the historical developments associated with long acting injections and implants providing suffi cient background to enable the reader to appreciate the historical development of the area and to use that knowledge as a foundation for the