McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 1 Introduction to drugs

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Preface

1 ■■ Phase II studies test potential drugs on individuals who have the disease the drugs are designed to treat. ■■ Phase III studies test dr gs in the clinical setting to determine any unanticipated effects or lack of effectiveness. ■■ TGA pregnancy categories indicate the potential or actual teratogenic effects of a drug. ■■ Generic drugs are sold under their chemical names, not brand names; they may be cheaper but are not necessarily as safe as brand-name drugs. This is followed by a series of review exercises in the Check your understanding s ction, to h lp focus student learning on the s minal i formatio presented in the chapter. This section assists students in testing their knowledge and preparing for examinations. Paul, S. P., Dewdney, C. & Lam, C. (2012). Managing children with constipation in the community. Nurse Prescribing, 10(6) , 274–284. Porth, C. M. (2011). Essentials of Pathophysiology: Concepts of Altered Health States (3rd edn). Philadelphia: Lippincott Williams & Wilkins. Porth, C. M. (2009). Pathophysiology: Concepts of Altered Health States (8th edn). Philadelphia: Lippincott Williams & Wilkins. Prynn, P. (2011). Managing adult constipation. Practice Nurse, 41(17) , 23–28. Sarre, R. (2005). Bowel pre aration. Australian P escriber, 28 , 16–17. Answers to the questions in this chapter can be found in Appendix A at the back of this book. MULTIPLE CHOICE Select the best response to the following. 1. Laxatives are drugs that are used to: DRUG EVALUATION After a chemical that might have therapeutic value is identified, it must undergo a series of scientific tests to evaluate its actual therapeutic and toxic effects. This process is tightly controlled by the Therapeutic Goods Administration (TGA) , an agency of the Australian Department of Health and Ageing that regulates the development and sale of drugs. TGA-regulated tests are designed to ensure the safety and reliability of any drug approved in this country. For every 100,000 chemicals that are identified as being potential drugs, only about five end up being marketed. Before receiving final TGA The text of each chapter ends with a summary of important concepts . CHAPTER SUMMARY ■■ Drugs are chemicals that are intro uced into the body to bring about some sort of chang . ■■ Drugs can come from many sources: plants, animals, inorganic elements nd synthetic prepar tions. ■■ Th TGA regulates the development and marketing of drugs safety and efficacy in Australia. ■■ Preclinical trial involve testing of potential drugs on laboratory an mals to determine their therapeutic and adverse effects. ■■ Phase I studies test potential drugs on healthy human subjects. P A R T 1 1 Drugs acting on the gastrointestinal system poractant alfa → → dipalmitoylphosphatidylcholine Curosurf Chapter openings also include a glossary of key terms and a list of featured drugs . Test your current knowledge of drugs with a PrepU Practice Quiz! Glossary of key terms azoles: a group of drugs used to treat fungal infections Candida : fungus that is normally found on mucous membranes; can cause yeast infection immunosuppressed individuals ergosterol: steroid-type protein found in the cell embrane of fungi; similar in c nfigurat fungus: a cellular organism with a hard cell wall that contains chitin and many polysaccha contains rgosterols mycosis: disease ca sed by a fungus tin a: fungus called ringworm that causes such infections as at l te’s foot, jo k itch and o ■■ TABLE 1.2 Elements us d for their therapeu ic effects Element Therapeutic use Aluminium Antacid to decrease gastric acidity Management of hyperphosphataemia Prevention of the formation of pho ph te urinary stones Fluorine (as fluoride) Prev nti n of dental cavities Prevention of osteoporosis Gold Treatment of rheumatoid arthritis Iron Treatment of iron deficiency anaemia 12 P A R T 1 Introduction to nursing pharmacology Therapeutic Guideli es provides a wid rang of drug i formation a series of systematic guid s, such as tibiotics and astrointestinal pharmacology. These guidelines draw upon a range of evaluated literature and research. McKenna’s Drug Handbook for Nursing and Mid- wifery has drug monographs organised alphabetically and includes care implications and important teaching points specifically relevant to nursing and midwifery practice. ■■ Orpha drug discov red to are not financ drugs. ■■ OTC drugs a self-treatment ■■ Information a variety of sou books, journ Glossary of key terms adverse effects: drug effects that are not the desired therapeutic effects; may be unple brand name: name given to a drug by the pharmaceutical company that developed it; chemical name: name that reflects the chemical structure of a drug drugs: chemicals that are introduced into the body to bring about some sort of change generic drugs: drugs sold by their chemical name; not brand (or trade) name products generic name: the original designation that a drug is given when the drug company th genetic engineering: process of altering DNA, usually of bacteria, to produce a chemic New Zealand Medicines and Medical Devices Safety Authority (MEDSAFE): a busine authority responsible for the regulation of therapeutic products in New Zealand orphan drugs: drugs that have been discovered but would not be profitable for a drug treat only a small number of people; these orphans can be adopted by drug compani over-the-counter (OTC) drugs: drugs that are available without a prescription for self-tr be safe when used as directed pharmacology: the study of the biological effects of chemicals pharmacotherapeutics: clinical pharmacology—the branch of pharmacology that deal medicine for the treatment, prevention and diagnosis of disease in humans phase I study: a pilot study of a potential drug conducted with a small number of select phase II study: a clinical study of a proposed drug by selected doctors using actual peo to treat; the subjects must provide informed consent phase III study: use of a proposed drug on a wide scale in the clinical setting with peopl to treat phase IV study: continual evaluation of a drug after it has been released for marketing post-marketing surveillance: monitoring the safety of medicines and medical devices i preclinical trials: initial trial of a chemical thought to have therapeutic potential; uses la teratogenic: having adverse effects on the fetus Therapeutic Goods Administration (TGA): Australian commonwealth government ag enforcement of drug evaluation and distribution policies SYSTEMIC ANTIFUNGALS Azole antifungals fluconazole itraconazole ketoconazole posaconazole terbi afine voriconazole Echinocandin antifungals anidulafungin caspofungin Other antifungals amphotericin B flucytosine griseofulvin nystatin TOPICAL ANTIFUNG Azole topical antifu butoconazole clotrimazole econazole ket conazole iconazole terbinafine each of which has slightly different properties, making a particular drug more desirable in a specific situa- tion. hroughout this book, the icon will be used to desig ate those drugs of a class that are considered the prototype of the class, the original drug in the class or the drug that has emerged as the most effective. For example, the cephalosporins are a large group of antibiotics derived from the same chemical structure. Alterations in th ch mical ri gs or attachments to that structure m ke it possible for some of these drugs to be absorbed orally, whereas others must e given par- enterally. Some of these drugs cause severe toxic effects (e.g. renal tox city), but others do not. KEY POINTS ■■ Clinical pharmacology is he s udy of drugs used to treat, diagno e or preven a disease. ■■ Drugs are chemicals that are introd ced into the body and affect the body’s chemical processes. ■■ Drugs can come from plants, foods, animals, salts of inorganic compounds or synthetic sources. KEY POINTS Numerous other drug handbooks are also on the market and readily available for nurs s and midwives to use. Journals Various journals can be us d to obtain drug informa- tion. For example, the Medical Letter is a monthly review of new drugs, drug classes and sp cific treat- ment protocols. Many clinical nursing and midwifery journals offer information on new drugs, drug errors and care implications. Australian Prescriber is a useful source of easily interpreted pharmacology information and is freely available online. Internet information Many individuals now use the Internet as a source of medical information and advice. Nur es and midwives need t become familiar with w a is available on the Internet and what people may be referencing, and have skills in critiquing the credibility of these sources. Knowi study m to find o ONLIN An extensive rang and learning and t b found online at thePoint at http:// Learn videos, Con review questions, Test your current knowledge of antifungal agents with a PrepU Practice Quiz! Key poin s appear pe iodically throughout each chapter to summarise important concepts. WEB LI Healthcare pro the following In www.anztpa.or Home page of t Product Agency www.australia Australian Pres www.medsafe.g Home page of www.nps.org.a Home page of Service. www.tga.gov.a Home page of t BIBLIOGRA Shah, S. B. & Hanauer, S. B. (2007). Treat pat ents w th inflammatory bowel diseas Reviews in Gastroenterology Disorders, Tobias, N., Mason, D., Lutkenhoff, M., Sto (2008). Management and principles of o childhood constipation. Journal of Pedi 12–23. Wang, M., Szucs, T. D. & Steffen, R. (2008 traveler’s diarrhea. Journ l of Travel Me Selby, W. (2010). Managing constipation in Prescriber, 33 , 116–119. Barton, J. H. & Em pharmaceutical potential refor Cardinale, V. (199 directions. Dru Davies, C. A. (200 of the regulatio devices in Austr Dempsey, J., Hilleg C H E C K Y O U R U N D E R S T A N D I N G C U MULTIPLE RESPONSE Select all that apply.

Part 3 focuses on drugs affecting the immune system, because recent knowledge about the immune system has made it the cornerstone of modern therapy. All of the immune system drugs act in ways in which the immune system would act if it were able. Recent immu- nological research has contributed to a much greater understanding of this system, making it important to position information about drugs affecting this system close to the beginning of the text instead of at the end, as has been the custom. Parts 4 and 5 address drugs that affect the nervous system, the basic functioning system of the body. Following the discussion of the nervous system, and closely linked with it in Part 6 , is the endocrine system. The sequence of these parts introduces students to the concept of control, teaches them about the inter­ relatedness of these two systems and prepares them for understanding many aspects of shared physiological function and the inevitable linking of the two systems into one: the neuro-endocrine system. Parts 7, 8 and 9 discuss drugs affecting the repro- ductive, cardiovascular and renal systems, respectively. The sequencing of cardiovascular and renal drugs is logical because most of the augmenting cardiovascular drugs, such as diuretics, affect the renal system. Part 10 covers drugs that act on the respiratory system, which provides the link between the left and right ventricles of the heart. Part 11 addresses drugs acting on the gastrointes- tinal system. The gastrointestinal system stands on its own; it does not share any actions with any other system. FEATURES OF THIS EDITION The text’s features are skilfully designed to support the text discussion, encouraging the student to look at the whole person and to focus on the essential informa- tion about each drug class. Important features focus on incorporating basic clinical skills, person safety, critical thinking and application of the material learned to the clinical scenario, helping the student to understand the pharmacology material. Chapter structure Each chapter opens with a list of learning objectives for that chapter, helping the student to understand what the key learning points will be. ■■ TABLE 1.1 Drugs derived from plants Plant Product Ricinus c mmunis Digitalis p rpurea (foxglove plant) Leaves Dried leaves Digitalis leaf Papaver somniferum (poppy plant) l -thyroxine,T 4 ← Eut oxsig, Oroxine ←

Seed Oil Castor oil (Neolid)

Unripe capsule Juice Opium Morphine (MS Contin, Ordine) Codeine Papaverine

pigs. Now genetic engineering —the process of altering DNA—permits scientists to produce human insulin by altering Escherichia coli bacteria, making insulin a better product without some of the impurities that come with animal products. Thyroid drugs and growth hormone preparations also may be obtained from animal thyroid and hypo- thalamic tissues. Many of these preparations are now created synthetically, however, and the synthetic prep rations are considered to be purer and safer than preparations derived from animals. Inorganic compounds Salts of various chemical elements can have therapeu- tic effects in the hum body. Aluminium, fluoride, iron and even gold are used to treat various conditions. The effects of these elements were usually discovered acci- dentally when a cause–effect relationship was observed. Table 1.2 shows examples of some elements used for their therapeutic eff cts. Synthetic sources Today, many drugs are developed sy thetically after chemicals in plants, animals or the environment have been tested and found to have therapeutic activity. Scien- tists use genetic engineering to alter bacteria to produce chemicals that are therapeutic and effective. Other tech- nical advances allow scientists to alter a chemical with proven therapeutic effectiveness to make it better. Some- times, a small change in a chemical’s structure can make that chemical more useful as a drug—more potent, more stable, less toxic. These techn l gic l advances have led to the development of groups o si il r drugs, all of which are derived from an original prototype, but 928

■■ TABLE 1.3 Comparison of generic, chemical, and brand names of drugs thyroxine sodium ← generic name →

chemical name brand names

Learning objectives Upon completion of this chapter, you should be able to: 1. Define the word pharmacology. 2. Outline the steps involved in developing and approving a new drug in Australia and New Zealand. 3. Describe the legislative controls on drugs that have abuse potential. 4. Differentiate between generic and brand-name drugs, over-the-counter and prescription drugs. 5. Explain the benefits and risks associated with the use of over-the-counter drugs. Introduction to drugs

Nursing and Mi (2nd Australian Williams & Wil 1. A nurse or midwife is preparing a person who has been prescribe teaching plan should include wh a. the importance of proper diet b. the need to take the drug for the full effect c. the importance of exercise d. the need to take advantage of by providing privacy and tim to work e. the need to limit fluids f. the importance of limiting th laxative use 2. A nurse or midwife might expec paraffin for which person? a. a debilitated person low on n b. a person with haemorrhoids c. a person with recent rectal su

a. increase the quantity of wastes excreted. b. speed the passage of the intestinal contents through the GI tract. c. increase digestion of intestinal contents. d. increase the water content of the intestinal contents. 2. The laxative of choice when mild stimulation is needed to prevent straining is: a. senna. b. castor oil. c. bisacodyl. d. magnesium sulphate. 3. Cathartic dependence can occur when: a. people do not use laxatives routinely and