PHARMACOLOGY CLEAR AND SIMPLE: A GUIDE TO DRUG CLASSIFFICATIONS AND DOSAGE CALCULATIONS 3 RD EDITION Cynthia J. Watkins 9780803666528

History of Pharmacology Medications, their origins, and their uses are older than any written records that we have. Many ancient cultures have contributed to the knowledge base and evolution of pharmacology, including Greek, Chinese, Egyptian, Persian, and Arabic. The healers were called by many names, but allshared an extensive knowledge of plants, minerals, and animal products. Pharmacology has evolved significantly from the days when these resources were used to cure the ill without understanding why they worked or did not work. Some ancient remedies are still valuable medicines today, whereas others have been discarded as worthless or dangerous. With the advent of scientific inquiry and technology, researchers around the world have created new and better medications. The ability to isolate pure substances and formulate drugs in a laboratory enables pharmaceutical companies to mass-produce needed medicines in a timely manner. In this chapter, you will learn about the history of pharmacology and sources used for developing drugs; the acceptance of alternative medicine, and its place in medicine; and the six main categories of drugs and their uses. LEARNING OUTCOMES At the end of this chapter, you should be able to: 1.1 Define all key terms. 1.2 List three societies critical to the development and evolution of pharmacology. 1.3 List four sources of drugs. 1.4 List 10 drugs, and record their sources. 3 4 UNIT 1 Introduction to Pharmacology KEY TERMS Al-Hawi Alternative medicine Antineoplastic Bovine Curative Destructive Diagnostic Drug/droog Ebers Papyrus Palliative Pharmacodynamics Pharmacology Pharmakon Porcine Prophylactic Replacement drugs Synthetic drugs ■ HISTORY OF PHARMACOLOGY The history of pharmacology helps us to understand that even though there have been huge advances in medications, scientists are coming to understand that by disregarding ancient practices, they have been missing a treasure trove of useful medications. Many practitioners are utilizing alternative medicine to maximize their patients’ health, and scientists are looking to older remedies to see if and why they work and how to reproduce them in the modern world. We as practitioners also need to understand that many patients are using many different forms of self-medication, from home remedies to substances they learned about on an infomercial that promise to cure all types of problems; if these substances are not understood, they may interfere or counteract a prescribed pharmaceutical medication. In other words, we need a complete picture of every substance patients are taking in order to assist in their care. The term pharmacology is of Greek origin from two words: pharmakon, meaning “medicine,” and ology, meaning “the study of.” Pharmakon also meant poison and remedy, poison because some of the early medicines were toxic enough to kill, and remedy because, at times, early medicines cured the illness. The word drug has a Dutch origin in which droog meant “dry” as in the use of dry herbs. Most ancient societies had little knowledge about the human body and how it worked, so treating illness was often based on trial and error. Early records document that treatments consisted of plants, minerals, and animal products because no other sources were available. “Healers” were known as wise men, shamans, witch doctors, medicine men and women, and so on (Fig. 1-1), depending on the culture, and were chosen based on their knowledge of which plants or other substance to use, how to prepare it, and how much to give the patient. Pharmacology in Ancient Times and Cultures Early documentation of medicine and various remedies is evident in several cultures. For example, “The Yellow Emperors’ Inner Classic,” a Chinese document, was a very early discussion of yin-yang and acupuncture. The first Chinese manual on pharmacology was written in the first century A.D. and included 365 medicines, 252 of which were herbs. In Egypt, a medical document called the Ebers Papyrus was written circa 1550 B.C. and lists about 700 “recipes” for a host of illnesses, from crocodile bites to psychiatric illnesses. Another document, the Al-Hawi, is a large, 20-volume medical book written by the physician Al-Razi in ancient Persia (Iran). It was translated into Latin in the 13th century and greatly influenced medicine in medieval Europe. The contributions from these cultures led to the advancement of pharmacology. When treatments for many conditions were discovered, the findings were recorded on papyrus or paper to pass on to future generations. Documenting this early information was extremely important, as belief systems changed over time. Without these earlier writings, traditional oral knowledge might have been lost or suppressed and much progress could not have been made. During the 17th and 18th centuries, there was a real lack of knowledge in the use of medications and their dangers. A prime example of this is mercury, which was used for a variety of ailments from skin conditions to syphilis. Specifically, in the late 1700s a prominent physician, Dr. Benjamin Rush used a mercury compound in high doses to treat yellow fever patients. Of course, it has since been discovered that mercury is so harmful to humans that we no longer use mercury blood pressure cuffs or thermometers for fear of exposure. CHAPTER 1 History of Pharmacology 5 FIGURE 1-1: Eskimo medicine man. (From the Library of Congress Prints and Photographs Division, Washington, D.C.) Pharmacological Advances Through the 19th and 20th Centuries Over time, an increasingly scientific approach to the discovery and understanding of drugs was taken. During the 1800s, chemists were able to identify and then isolate the active ingredients (those pure chemicals in the plants that had the actual therapeutic properties). They were also able to determine how the drug acted on the body. This marked the beginning of modern pharmacology. Up until the early 1900s, preparing medicine was very labor-intensive; the pharmacist had to distill and prepare each medicine when it was ordered (Fig. 1-2). Not until World War II (1939 to 1945) did the mass-production of medicine begin (Fig. 1-3). More U.S. soldiers died in World War I from infection and accidents than from actual combat injuries; however, the mass-production of penicillin minimized the number of deaths from infection during World War II (Table 1-1). For instance, the death rate from pneumonia FIGURE 1-2: Pharmacist preparing a prescription, 1939. (From the Library of Congress Prints and Photographs Division, Washington, D.C.) 6 UNIT 1 Introduction to Pharmacology TABLE 1.1 U.S. Casualties in Major Wars War Number Serving Battle Deaths Disease and Accidents FIGURE 1-3: Mass-production of medication, 1944. (From the Library of Congress Prints and Photographs Division, Washington, D.C.) Civil War 2,213,363 140,414 224,097 Spanish-American War 306,760 385 2,061 World War I 4,743,826 53,513 63,195 World War II 16,353,659 292,131 115,185 Source: U.S. Department of Justice in the U.S. Army was 18% during World War I, decreasing to 1% during World War II. Death from combat injuries complicated by infections also decreased. With the discoveries of new drugs like penicillin that could save millions of lives, the belief grew that new drugs must be better than old standard herbs and treatments, especially if created or refined in a scientific manner. Pharmacology therefore advanced rapidly in the second half of the 20th century as many new drugs were either discovered or developed. In an effort to discover possible new drugs, researchers studied plants, marine animals, and micro-organisms in soil, water, and air. Partially or totally synthesized medications were produced by combining two or more compounds or elements. Partially synthesized medications were made by adding a pure chemical to a naturalsubstance. Totally synthesized medications were created by combing two or more pure chemicals to produce a new substance that could be used as a medication. One major breakthrough was the discovery of ways to create large amounts of viable drugs from a small amount of natural resources using genetic engineering. For example, human insulin can be mass-produced by adding the human insulin gene to a nonpathogenic strain of Escherichia coli. Pharmacology in the 21st Century In the 21st century science is booming. One of the most promising advances in the field of medications is that of pharmacogenetics, which is the “study of individual candidate genes as powerful tools to explain interindividual variability in drug response.” In other words, the patient’s genetic material is analyzed, and then in the case of cancer, the tumor’s genetics are analyzed to figure out the best drug and what dosage will work best to combat the disease. Currently there are certain medications and doses used to treat conditions for every adult patient with that condition. Through these advances in pharmacogenetics, the ability to individualize drugs and their dosage is happening in the treatment of HIV and rheumatoid arthritis. In addition, the hope is that in the future we can specifically tailor drugs and dosages for opioids and antihypertensives among other medications. ■ SOURCES OF DRUGS Although most drugs are now manufactured in l