In both primary and secondary health care, the use of medicines is the most common intervention. However, the use of medicines is not without risk. Selecting and prescribing drugs is increasingly complex and demanding, and it is undertaken as part of a multi-disciplinary process that involves pharmacists, some of whom are now prescribers in their own right, along with doctors, nurses and other members of the healthcare team. All must strive to promote safe, appropriate and cost-effective prescribing that respects patient choice and promotes adherence. This book was written to help the reader understand and address many of these issues. It is unashamedly written from a pharmacy perspective, although we do hope those from other disciplines will also ind it of use. We have made considerable effort to update each chapter and ensure the content is relevant to current practice. Selected website addresses have been included to assist those who want to obtain further information, and many references are now available electronically. However, knowledge in therapeutics progresses rapidly, changes to dose regimens and licensed indications are frequent, safety issues emerge with established drugs and new medicines appear at regular intervals. Yesterday another landmark study may have been published that added to, or perhaps altered, the evidence base for a speciic treatment. Together with the ongoing publication of national and international guidelines and frameworks, the face of therapeutics is ever changing. It is therefore inevitable that some sections of this book will date more quickly than others. In practice, many licensed drugs are used ‘off label’ or ‘near label’ when prescribed for a certain indication or used in a speciic patient group, such as children. To omit reference to these agents in the relevant chapter would leave an apparent gap in therapeutic management. As a consequence, we have encouraged our authors to present details of all key drugs used, along with details of the prescribed regimens, even if not licensed for that speciic indication. There is, however, a downside to this approach. The reader must always use this text critically and with caution. If this is done, the book will serve as a valuable learning resource and help the reader understand some of the principles of therapeutics. We hope that, in some small way, this will also assist in achieving positive patient outcomes.