Principles of clinical pharmacology

Pharmacology is defined as the study of the effects of drugs on the function of a living organism. It is an inte­grative discipline that tackles drug/ compound behaviours in varied physiological systems and links these to cellular and molecular mechanisms of action. As a scientific endeavour, pharmacology evolved from the early identification of therapeutic properties of nat­ural compounds, with herbal medicines and relatively complex pharmacopoeias widely used in early cultures. Despite this, lack of understanding of the physio­logical, pathological, and chemical processes governing the human body prevented the early establishment of pharmacology as a scientific discipline. Since then, pharmacology has progressed to be considered a fully developed integrative science that employs techniques and theories from various disciplines, such as chemistry, biochemistry, genomics, medicinal chemistry, physi­ology, and cellular and molecular biology. Collectively, these are applied to study disease causality and the rele­vant mechanistic action of compounds, to establish new treatments. In the last 100 years, the importance of clinical pharmacology has increased in line with the scientific and technological advances in biomedical research. Benefits gained from molecular and cellular approaches have enabled a more comprehensive analysis of drugs and their actions in functional context. Now, clinical pharmacology and therapeutics encompass the dis­covery, development, regulation, and application of drugs in a process that integrates scientific research with clinical practice to better treat illness and preserve health. Within this textbook the principles of pharmacology are discussed by therapeutic area so that the reader can link disease pathophysiology, drug mechanism, and modern prescribing behaviours for conditions commonly seen in clinical practice. There are, however, fundamental concepts that are universal in understanding the interaction between drugs and their ‘targets’, including receptor pharmacology, genomic pharmacology, and pharmacokinetics. The pharmacological receptor models preceded by many years the knowledge of the receptor as an entity. It was not until the last 150 years that a series of contributions from many notable biologists and chemists established the principles that founded modern day pharmacology. They produced a significant paradigm shift in therapeutics, where empirical descriptors of the activities observed (heating, cooling, moistening, emetic, etc.) were replaced by the concept of a ‘target’. After more than a century, the basic receptor concept is still the foundation of biomed­ical research and drug discovery.