Pharmacology
Pharmacology is the study of the changes produced in living animals by chemical substances. There is a great emphasis on the mechanisms underlying the actions of drugs, and both physicians and patients acknowledge the role of drugs in modern therapy. Drug treatment is recognized as the primary modality in the prevention and alleviation of diseases. For hundreds of years most drugs were impure mixtures of only vaguely known composition, and primarily of plant and animal origin. A physician was required to know only what effects might be anticipated from a particular preparation. How the mixture produced the effects was beyond the scope of knowledge of that period. Over the past 60 years the situation has changed and today the physician should know the overt expected effects of a drug, its precise mechanism of action, its elimination routes, its side effects and its potential toxicity. Systematic investigations contributing to such knowledge of the effects of drugs are most often based on results from animal experimentation and the use of isolated and purified active substances and these developed in the mid-nineteenth century. Pharmacologists today draw on a number of biomedical disciplines, including physiology, pathology, biochemistry, and bacteriology, to understand the interaction of drugs with body constituents as completely as possible.
There are several reasons for considering pharmacology as one of the increasingly important basic sciences of medicine. Large numbers of drugs are used in the practice of medicine. They cannot be applied intelligently or even safely without some insight into their mode of action, side effects, toxicity, and metabolism. As powerful new drugs are introduced, the necessity for adequate pharmacological knowledge on the part of the podiatrist becomes increasingly mandatory. Pharmacology embraces a number of sciences, including pharmacodynamics (the study of the action of drugs on a living body), therapeutics (use of drugs and the method of administration in the treatment of diseases), materia medica (the study of the source, composition, characteristics, and preparation of drugs), toxicology (the study of poisons and their action and also the ways of treating poisoning), pharmaceutical chemistry (chemistry in relation to drugs), and pharmacy (the preparation and dispensing of drugs for medical use).
As recently as the 1920s, relatively few medically beneficial active ingredients existed. Most active ingredients were used in only partially purified form, generally from plant or animal sources. Since then, vastly improved tools and methods have developed and it is now possible to identify which compounds in the earlier crude mixtures produce beneficial or undesirable effects. Techniques of synthetic organic chemistry have been used to define the chemical structures of drugs, to synthesize analogs and to test them for pharmacological activity. A significant breakthrough occurred in the 1940s when it was discovered that microorganisms could produce compounds called antiobiotics, which were capable of killing other microorganisms. During the 1940s and 1950s, pharmacology depended greatly on organic chemistry to provide the background necessary to synthesize new drugs. Developments in biochemistry during the 1960s through to the present have changed the emphasis to molecular pharmacology and qualitative and quantitative molecular mechanisms of cellular processes. It is now possible to identify, isolate and characterize in the body fluid or tissue certain constituent changes responsible for the beneficial effects of drugs. Most recently, advances in genetic engineering and molecular biology have accelerated research on the nature of drug sites of action. Such knowledge may provide a sound basis for rational drug use in medial therapy as well as provide a foundation for the design of improved drugs with minimal side effects.
In the field of rational drug design, it is important to realize that each patient is unique. Some respond adequately to a selected drug while others may experience strong side effects. Pharmacogenetics is that area of pharmacology concerned with the unanticipated or unusual responses to drugs that may have a hereditary basis for their action. These effects must be distinguished from toxic side effects that can generally be anticipated or result from allergic manifestations. Today, pharmacogenetics is a vastly developing field in the wake of the human genome project. It is now being anticipated that in the future it will be possible to design drugs specifically for individual patients on the basis of an understanding of their genetic code.
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