Pharmaceuticals (drugs) are substances that prevent, moderate, or cure illnesses. We begin the chapter with a drug that has probably been used by all readers of this book. Its discovery and development is an introduction into how a new drug often comes into existence. All the drugs mentioned (indeed, most of the drugs used today) contain the element carbon. Therefore, we embark on a brief excursion into organic chemistry, the realm of carbon compounds. The principles governing the structure of organic molecules are those we have already applied to other molecules in previous chapters. The molecular structures of organic compounds offer the opportunity to explore new features such as isomers and functional groups. Both are of great importance in linking molecular structure to drug function. Examples of characteristic drug activity are provided by a group used to control pain, but a more general treatment of the topic introduces the concept of the fit between the drug and the biochemical site at which it acts. Sometimes, activity depends on chirality, the subtle property of three-dimensional structure that makes some molecules related like right and left hands.

Discussion then shifts to steroids, one of the most interesting and important families of biologically active compounds. Members of the steroid family that are treated in some depth are cholesterol, sex hormones, contraceptives, aborting agents, and anabolic steroids. These compounds, or at least their uses, are familiar to almost everyone because they have often been steeped in controversy. By setting the steroids in their social context we explore a number of these issues. We turn next to drug testing and approval, the lengthy and demanding process that is necessary to obtain consent to sell, distribute, and use a new drug. Here again, we will find that risks and benefits are present, whether using the original or generic forms of drugs or whether they are prescription or over-the-counter medications. The chapter ends with a section outlining some of the chemical issues of alternative medicines such as herbal remedies.