The first edition of this textbook, published in 1941, is often credited with organizing the field of pharmacology, giving it intellectual validity and an academic identity *. That first edition began: "The subject of pharmacology is a broad one and embraces the knowledge of the source, physical and chemical properties, compounding, physiological actions, absorption, fate, and excretion, and therapeutic uses of drugs. A drug may be broadly defined as any chemical agent that affects living protoplasm, and few substances would escape inclusion by this definition." These two sentences still serve us well. This first section of the 12th edition of this textbook provides the underpinnings for these definitions by exploring the processes of drug invention and development into a therapeutic entity, followed by the basic properties of the interactions between the drug and biological systems: pharmacodynamics, pharmacokinetics (including drug transport and metabolism), and pharmacogenomics. Subsequent sections deal with the use of drugs as therapeutic agents in human subjects.
We intentionally use the term invention to describe the process by which a new drug is identified and brought to medical practice, rather than the more conventional term discovery. This significant semantic change was suggested to us by our colleague Michael S. Brown, MD, and it is appropriate. In the past, drugs were discovered as natural products and used as such. Today, useful drugs are rarely discovered hiding somewhere waiting to be found; rather, they are sculpted and brought into being based on experimentation and optimization of many independent properties. The term invention emphasizes this process; there is little serendipity.
FROM EARLY EXPERIENCES WITH PLANTS TO MODERN CHEMISTRY
Man's fascination—and sometimes infatuation—with chemicals (i.e., drugs) that alter biological function is ancient and arose as a result of experience with and dependence on plants. Most plants are root-bound, and many have become capable of elaborate chemical syntheses, producing harmful compounds for defense that animals learned to avoid and man learned to exploit. Many examples are described in earlier editions of this text: the appreciation of coffee (caffeine) by the prior of an Arabian convent who noted the behavior of goats that gamboled and frisked through the night after eating the berries of the coffee plant, the use of mushrooms or the deadly nightshade plant (containing the belladonna alkaloids atropine and scopolamine) by professional poisoners, and a rather different use of belladonna ("beautiful lady") to dilate pupils. Other examples include the uses of the Chinese herb ma huang (containing ephedrine) for over 5000 years as a circulatory stimulant, curare-containing arrow poisons used for centuries by South American Indians to paralyze and kill animals hunted for food, and poppy juice (opium) containing morphine (from the Greek Morpheus, the god of dreams) for pain relief and control of dysenteries. Morphine, of course, has well-known addicting properties, mimicked in some ways by other problematic ("recreational") natural products—nicotine, cocaine, and ethanol.