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Definition: pharmacology from The Penguin Dictionary of Science

The study of compounds that produce physiological effects in the body, particularly those of medical significance, and their actions.


Summary Article: Pharmacology from Encyclopedia of Global Health

Pharmacology is the science and practice of developing and administering chemicals as agents in the treatment of diseases. Pharmaceuticals are drugs used as to treat disease, yet they are also abused for “recreational” purposes or used for criminal purposes.

The discipline of pharmacology comprises more than just the chemistry of drugs. It also includes the study of how living organisms react to exposure to drugs. The interactions may be anti-pathogenic, therapeutic, or toxic. The later area of study is toxicology, or the study of poisonous effects.

Diseases afflict plants, animals and humans. The use of chemical agents to treat disease is ancient. Folklore among tribal peoples such as the American Indians and traditional medical systems such as those of China and India developed a wide range of pharmaceuticals.

The ancient Greeks, led by Galen, Hippocrates and others, developed medicine in a systematic philosophical manner. Greek medical science was inherited by the Arabs and their converts following the Arabian conquests. Within roughly a century the entire corpus of Greek medical science was translated into Arabic with the aid of Christian and Jewish physicians. To it was added the medical knowledge of the Persians and the physicians of India.

The medical knowledge of the Islamic world was transmitted to the West during and after the Crusades from sources in the Levant and in Spain. Some new medical knowledge began to filter back to Europe during the voyages of sailors in the age of exploration. They also brought back new disease. The herbal remedies and new diseases were a stimulus to research into biology, diseases, and medicinal remedies.

Probably the most important advance was the development of vaccines following Edward Jenner’s (1749–1823) discovery that inoculation with cow pox protected against small pox. Virology, the study of viruses, developed in the early 1900s from work done on viruses by Frederick William Twort and Felix d’Herelle. The growing understanding of viruses enabled vaccines to be developed to combat them. With the deadly global influenza pandemic at the end or World War I the need became acute.

The advances in chemistry of the 19th century bore dramatic fruit for the pharmaceutical industry after 1900. The textile industry was the first to undergo industrialization and adoption of the factory system during the Industrial Revolution. Its products had been dyed with natural dyes until modern chemists began the development of modern sulfur dyes. The chemists, many of whom were Germans working with coal, were able to develop new dyes for coloring fabrics. However, it was also noticed that some microbes took the dyes into their systems, often with fatal effects.

The modern pharmaceutical industry has since grown into a global multi-billion dollar giant. Today the competition to develop new drugs is intense and there are strong economic and political motivations to advance new medicines. There have also arisen in the United States, and to a similar degree in other countries, government agencies that regulate the production and distribution of medicines. One obvious reason is drug abuse. Another is to protect the public for charlatans. Quackery abounded in the United States in the 19th century. Numerous “snake oil salesmen” traveled the country selling remedies that were often simple mixtures of alcohol and opium.

Today the Food and Drug Administration regulates pharmaceuticals and enforces standards set by the United States pharmacopoeia. In Europe, the European Union’s agency for regulating the development and application of pharmaceuticals is the European Medicines Agency (EMEA). It also evaluates drugs developed in Africa and the Middle East.

Medicinal drugs are usually put into a dozen categories. Those used to treat humans are classified according to the way that they affect the human body. They can also be classified by their chemical makeup, the disease they fight, by the affect they have on the heart or blood vessels, or by their affect on the nervous system. Manufactured drugs have three names: a scientific chemical name, a manufacturer approved generic name, and the brand name of its manufacturer.

Penicillin, an antibiotic, is probably the most famous of the infection fighting drugs. Others antibiotics include the sulfa drugs (sulfonamides). Vaccines, antiserums, and immunoglobulins are infectious disease preventing drugs. These drugs work by stimulating the body to create antibodies to fight potential diseases such as measles, small pox, polio and others. When the antibodies combine with the antigens of the bacteria or virus they render them harmless. Antiserums and immunoglobulins also neutralize the antigens of the infectious disease. They provide protection against the antigens of microbes that cause diseases such as diphtheria, tetanus, hepatitis or rabies.

The cardiovascular drugs affect the heart or blood vessels by normalizing irregular heartbeats, stimulating the heart’s beat so that more blood is pumped, enlarge small blood vessels, or in the case of hypertensive drugs treat high blood pressure.

The nervous system is affected by drugs such as analgesics, anesthetics, hallucinogens, stimulants, and depressants. The analgesic drugs relieve pain, but because some contain a narcotic they are subject to abuse. Narcotics (analgesia plus a sedative) include codeine, heroin, and morphine. Aspirin is a non-narcotic analgesic.

The general anesthetics are drugs that produce a state of sedation that blocks sensations. Ether halothane and thiopental have been used in surgery.

Hallucinogens or psychedelic drugs such as LSD (lysergic acid diethylmide), marijuana, and mescaline produce hallucinations. Mushrooms and other plants are often grown illegally and are known to cause drug addiction.

Stimulant drugs affect the nervous system. They can reduce fatigue, stimulate the kidneys, or produce other affects. Caffeine, cocaine, and amphetamines are drugs in this category. The last two have been subject to abuse.

Depressants cause the nervous system to become relaxed so that tension and worry are diminished. Tranquilizers (anti-anxiety agents), alcohol, and sedative-hypnotics are depressants. Other depressants include benzodiazepines and barbiturates. Non-barbiturate sedatives include chloral hydrate and paraldehyde. Their recreational drug abuse is widespread.

Other drug types include the diuretics, hormone therapy drugs, vitamins and immunosuppressive drugs. Drugs used in chemotherapy involve anti-tumor (antineoplastic) chemicals.

Drug abuse has two major forms: recreational and medicinal. The recreational abuse of drugs has created criminal empires. In areas such as Burma or Afghanistan where opium is produced, or South America where the coca leaf grows, crops have been subjected to efforts at eradication that involve the use of defoliants. The impact on the natural environment has been negative.

The medicinal abuse of drugs is probably even more widespread. Failure to handle medicines properly has contributed to drug resistance to bacteria strains. It has also led to a race to continually produce new drugs against “stronger bugs.”

Another form of medicinal drug abuse is its use to prevent disease of to stimulate animal growth, thereby increasing meat production. The side effects have been negative in a number of cases.

Today the pharmaceutical industry is searching the globe for any plant or lifeform that may have medicinal benefits. The early 20th century distain for folk remedies has been replaced by a thorough search of the earth for anything with medicinal promise. The industry stands to gain billions of dollars from new cures.

The notion of throughput is now being using in the pharmaceutical industry. Advances in several sciences have lead to the development of many new drugs. The human genome project has increased knowledge of human genes immensely. Because there are thousands of units of proteins in human DNA, the knowledge is now available to seek new receptors for possible medicines.

The development of robot chemistry at the end of the 20th century has made it possible to assemble vast numbers of chemicals that can then be tested on the thousands of receptor sites in proteins. Where previously a skilled chemist would have done well to develop one or two chemicals a week, these new techniques allow a single chemist to develop thousands of new compounds in the same time. The screening of such an enormous number of chemical compounds against a vast number of receptor sites would have needed armies of researchers just a few decades ago. Now using high throughput screening technology, thousands of chemicals can be tested against thousands of receptor sites. Many new companies have arisen that synthesize computerized chemical libraries containing millions of different chemicals.

Pharmaceutical companies will often buy high throughput technology systems in order to test for some target receptor that is of interest. Using the computer’s database of chemical formulas, it is possible for a company to screen up to a million different chemicals against a chosen receptor site in only a month. However, out of every five thousand possible drugs only about one makes it to the market. Even then recalls due to unexpected side effects are not uncommon.

To develop a new medicine typically takes three or more years and is very expensive. Once the medicine is produced it has to undergo clinical trials that can take and additional three to six years. Sometimes there are accidental discoveries from side effects. Most side effects will eliminate a drug from use, but in the case of Viagra, it stimulated a whole new range of erectile dysfunction medications.

    SEE ALSO:
  • Pharmacologist; Prescription Drug Abuse.

BIBLIOGRAPHY
  • George M. Brenner; Craig W. Stevens, Pharmacology (Elsevier Health Sciences, 2006).
  • Howard Brody, Hooked: How Medicine’s Dependence on the Pharmaceutical Industry Undermines Professional Ethics (Rowman & Littlefield Publishers, Inc., 2007).
  • Richard A. Epstein, Overdose: How Excessive Government Regulation Stifles Pharmaceutical Innovation (Yale University Press, 2006).
  • Sved Imtiaz Haider, Pharmaceutical Master Validation Plan: The Ultimate Guide to FDA, GMP, and GLP Compliance (CRC Press, 2001).
  • Leslie Iversen, Drugs: A Very Short Introduction (Oxford University Press, 2001).
  • Bertram G. Katzung, Basic & Clinical Pharmacology (McGraw-Hill, 2006).
  • Howard L. McLeod, ed., Handbook of Anticancer PharmacoKinetics and Pharmacodynamics (Springer-Verlag, 2004).
  • Michael A. Santoro; Thomas M. Gorrie, eds., Ethics and the Pharmaceutical Industry (Cambridge University Press, 2005).
  • Sonia Shah, Body Hunters: Testing New Drugs on the World’s Poorest Patients (The New Press, 2006).
  • Walter Sneader, Drug Discovery: A History (John Wiley & Sons, 2004).
  • Linda Waide; Berta Roland, Pharmacology Made Easy for NCLEX-RN: Review and Study Guide (Chicago Review Press, 2001).
  • Andrew J. Waskey
    Dalton State College
    Copyright © 2008 by SAGE Publications, Inc.

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