What is Pharmacology?

Pharmacology is the study of how drugs exert their effects on living systems. Drugs can be defined as chemical agents that interact with specific target molecules, thereby producing a biological effect. Pharmacologists work to indentify drug targets in order to learn how drugs work. Pharmacologists also study the ways in which drugs are modified within organisms. A fundamental knowledge of the underlying biological processes is required to achieve these objectives and to identify new targets for future therapeutic intervention. Thus, pharmacologists study many basic aspects of cellular and molecular biology.

In recent years, there has been a dramatic increase in the rate at which novel drugs are discovered and marketed. As a consequence, it is essential to train a new generation of pharmacologists who will meet the challenges this opportunity presents.

Pharmacy, often confused with pharmacology, is a wholly separate profession concerned with the preparation, dispensing and use of medications. Whereas pharmacy can be viewed as a profession that is part of health care delivery and information systems, pharmacology is a basic biomedical scientific discipline.

A history of pharmacology

Ancient Times
The mists of antiquity shroud the early history of humankind's efforts to harness the healing properties of natural compounds. However, it is known for certain that ancient peoples made extensive use of plant, animal and mineral sources for this purpose. The Ebers papyrus, thought to have been written in Egypt in the 16^th century B.C., lists the extensive pharmacopia of that civilization. Included in this this are: beer, turpentine, myrrh, juniper berries, poppy, lead, salt and crushed precious stones. Also included were products derived from animals, including lizard's blood, swine teeth, goose grease, ass hooves and the excreta from various animals. The effects of many of these drugs on patients of antiquity can only be imagined. However, it is doubtless that many successes were encountered.

From ancient China comes evidence of that culture's extensive efforts to heal through the use of natural products. The Pen Tsao, or Great Herbal, comprised forty volumes describing several thousands of prescriptions. Interestingly, the eastern herb Artemisia annua L. (wormwood), used in China since antiquity to treat fevers, is the source of the modern drug qinghaosu, which shows great promise as a modern anti-malarial compound.

Antiquity to the modern era
The ancients considered disease a consequence of demonic possession, or the wrath of god. Thus, in ancient times, the treatment of illness with natural products was invariably accompanied by religious rituals deemed essential to the healing process. Eventually, there was a greater appreciation that the natural products themselves held the power to cure. However, traditional remedies still generally consisted of complex mixtures of distinct herbs and minerals, perhaps only one (if any) of which possessed activity. For example, the purple foxglove, Digitalis purpurea, was one of twenty herbs used in a folk remedy to treat dropsy in 18^th century England. From the leaves of this plant was isolated the cardiac glycoside digitalis, a drug still used today to treat heart failure.

Over time, as a more sophisticated view of illness evolved, an increasingly scientific approach to the isolation of drugs from natural products was taken. In the early 19^th century, morphine was isolated from the opium poppy (Papaver somniferum) and the anti-malarial compound quinine from the bark of the cinchona tree (Cinchona officinalis). These, and additional advances in the fields of chemistry and physiology, lead to the birth of modern pharmacology in the latter half of the 19^th century. Thus, the ancient discipline of Materia Medica, devoted to understanding the origin, preparation and therapeutic applications of medicinal compounds, has evolved into the experimental science of pharmacology, which is devoted to understanding the physiological action of these molecules. In America, this transformation was marked by the creation of the American Society for Pharmacology and Experimental Therapeutics (ASPET) in 1908.

The modern era
In 1897, Felix Hoffman, a reserach chemist employed by the "Farbenfabrikin vorm. Freidr. Bayer and Co." synthesized acetylsalicylic acid. On February 1, 1899, Aspirin® was registered as a trademark. On March 6^th of the same year, this drug was registered with the Imperial Patent Office in Berlin. Aspirin quickly become popular worldwide, and remains an important drug today. (Interestingly, it was not until 1971 that Sir John Vane discovered the mechanism of action of aspirin, a feat that earned him the 1981 Nobel Prize for Medicine.) The 20^th century has witnessed the discovery of a steady stream of important new drugs that have immeasurably improved the human condition. Indeed, it is difficult to imagine our world without these important therapeutic agents. Not very long ago, vast numbers of humans perished prematurely or suffered an existence filled with pain due to the effects of infection or disorders that are now successfully treated. Progress has been particularly noteworthy in the areas of chemotherapy of cancer and microbial infections, a field that came into existence in this century. Likewise, we have made significant progress in our ability to use drugs to treat chronic conditions, such as diabetes, hypertension, and depression. It is hard to measure the contribution these drugs have made to improve the human condition. However, as the recent AIDS pandemic illustrates, at the dawning of the new millennium there remain many significant challenges, as well as opportunities, for those interested in pursuing a career in pharmacology.

What questions do pharmacologists ask?

• What mechanisms are responsible for drug tolerance and drug addiction, and how are these manifested?
• What are the molecular targets for drugs? How do these agents produce their effects?
• How does drug-resistance evolve in cancer cells and microbes?
• Can drugs be used to prevent conditions such as cancer, heart disease and neurodegeneration?
• How does the body terminate the action of a drug?
• Can drugs that control obesity be developed?
• What causes aging? Can drugs reverse or retard this process?
• How are the electrical activities of the heart and brain controlled, and how do drugs influence such activities?

Modern pharmacology is divided into many specialties*:

Neuropharmacology

Neuropharmacologists engage in research into the mechanism of action of drugs that affect the central and peripheral nervous systems. As with most of the pharmacologic specialties, drugs are also used as tools to gain insight into both normal and abnormal function.

Behavioral Pharmacology

Behavioral Pharmacologists study the influence of drugs on higher cognitive functions, including learning, memory, and addiction.

Cardiovascular Pharmacology

Investigators in this area study the mechanism of action of drugs used in the treatment of conditions such as high blood pressure and cardiac failure. Experiments are conducted both at the molecular level and in intact organisms.

Molecular Pharmacology

The techniques of molecular biology are applied to address questions in pharmacology. Molecular cloning and gene expression technology are applied both to cells in culture as well as to intact organisms to identify new drug targets and understand the molecular mechanism of action of drugs.

Clinical Pharmacology

Clinical pharmacology links basic pharmacology with the goal of treating sick people or preventing sickness. Clinical pharmacologists are interested in the actions of drugs in humans at the molecular, sub-cellular, organ, and whole-body levels.

Chemotherapy

Pharmacologists in this area work to understand the mechanism of action of agents that exhibit selective toxicity, killing invading microbes or cancer cells, while sparing those of the host.

Biochemical Pharmacology

Methods used to study cell biology and biochemistry are employed to gain insight into how therapeutic agents influence the intracellular 'machinery of life'.

*Specialties not listed here include toxicology, pharmacogenetics, renal pharmacology, and others.