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Chapter 20 Pharmacology Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 1 Objectives 1. Recognize common definitions and nomenclature associated with pharmacology. 2. Recognize the various classifications of drugs. 3. Describe the actions, indications, and precautions related to various drugs. 4. List the five rights of drug administration. 5. List the methods of drug administration. 6. Prepare intravenous drugs for injection. 7. Perform venipuncture using appropriate universal precautions. 8. Describe documentation procedures related to drug administration. Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 2 Pharmacology • A drug is any chemical substance that produces a biologic response in a living system. • A drug is a substance used as medicine to aid in the diagnosis, treatment, or prevention of disease. • The science concerned with the origin, nature, effects, and uses of drugs is called pharmacology. Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 3 1 Physicians’ Desk Reference • Commonly called PDR • Annual publication that contains current product information • Pages are color coded and list drugs by both their generic and their brand names • PDR gives the accepted uses, side effects, contraindications, and doses for available drugs • IF PDR unavailable, speak with pharmacist Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 4 Drug Classifications and Dosages • Classification by Action • Classification by Legal name • Dosage Forms Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 5 Drug Profile • • • • • • • • Chemical composition Absorption characteristics Distribution characteristics Metabolic characteristics Elimination characteristics Indications, actions, and effects Interactions and contraindications Patient reactions Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 6 2 Pharmacokinetics Process • • • • Absorption Distribution Metabolism Excretion Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 7 Drug Absorption • How it gets into the circulatory system • Bioavailability is the amount of drug that reaches systemic circulation • Drugs must be absorbed in order to begin activity Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 8 Drug Distribution • Absorption of drug into the body and its travel to the intended site of activity via circulatory system • Affected by several factors Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 9 3 Drug Metabolism (Biotransformation) • The metabolism of the drug by altering its chemical structure • Most drugs metabolized by liver in the hepatic microsomal enzyme system • Biotransformation occurs through four major pathways • Metabolism affected by many factors Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 10 Factors That Influence Drug Action • • • • • • • Patient Age Health Status Time of Day Emotional State Other Drugs in the Body Genetic Variations Disease State of the Body Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 11 Drug Excretion • Removal of drug from the body • Principally performed by the kidneys • Also occurs by way of: – Biliary tract – Lungs – Sweat – Saliva – Breast milk Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 12 4 Classes of Drug Reactions •Allergic •Idiosyncratic •Iatrogenic Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 13 Osmolality • The measure of the total number of particles in solution per kilogram of water • Great biologic significance • Most adverse reactions to contrast are a result of the osmolality of the agent • Ionic contrast agents are HOCM • Nonionic contrast agents are typically LOCM and quite popular Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 14 When Administering Drugs You Must: 1. Record Name of Drug 2. Record Route of Administration 3. Record Time of Administration 4. Record Patient’s Reaction to the Drug You Administered Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 15 5 Factors That Influence Drug Action • • • • • • • Patient Age Health Status Time of Day Emotional State Other Drugs in the Body Genetic Variations Disease State of the Body Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 16 Rights of Drug Administration • • • • • Right Drug Right Amount Right Patient Right Time Right Route Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 17 Drug Administration Routes • Enteral Routes – Oral – Rectal – Vaginal • Parenteral Routes – Intramuscular – Intravenous – Subcutaneous – Intradermal Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 18 6 Drug Administration Supplies • Parenteral administration uses syringes and needles • An angiocath is a safer device compared with other systems to use when performing venipuncture • Needle diameters expressed in gauges • Drugs intended for use by parenteral administration are packaged in two different kinds of containers Insert Fig 20-1 here FIG. 20-1 Parts of a syringe. Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 19 Routes of Drug Administration • • • • • Oral Sublingual Topical Rectal Parenteral Ampule Vial Prefilled syringe Infusion Drip Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 20 Parenteral Administration • Drugs that are injected have a rapid onset of action because they are absorbed directly into the bloodstream • All forms of parenteral administration require the use of a needle, syringe, and container • Requires aseptic technique • Four routes of injection Insert Fig 20-3 here FIG. 20-3 Parts of a needle. Insert Fig 20-5 here FIG. 20-5 Needle bevels. Long or regular bevels are usually used for intramuscular or subcutaneous injections. Short bevels are commonly used for intravenous injections. Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 21 7 Parenteral Injections Subcutaneous Injection Insert Fig 20-10 here FIG. 20-10 Proper needle placement for injection into the subcutaneous tissue. The needle is inserted at a 45-degree angle. Intramuscular Injection Insert Fig 20-11 here FIG. 20-11 Proper needle placement for injection into the muscle tissue. The needle is inserted at a 90-degree angle. Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 22 Venipuncture • Drug is placed directly into a vein. • Needle length and gauge depend on the viscosity of the drug, the site selected, and the specific method of injection. • While injecting, observe site for extravasation or infiltration. • If extravasation occurs, the first step is to remove the needle, apply pressure to the injection site, and apply warm moist heat to relieve the discomfort. FIG. 20-12 Sites commonly used for venipuncture. Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 23 Drip Infusion • Involves infusion via an IV assembly • Used for large volumes of fluid administered • Patients often come with IV pumps • Pay attention to the IV pump alarms Insert Fig 20-13 D here FIG. 20-13 Drip infusion. Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 24 8 Characteristics of Valid Prescription • Patient name, room number, address, and ID number • Drug name • Dosage • Dosage form • Route of administration • Date order is written • Signature of prescriber Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 25 Conclusion • • • • • • • The radiologic technologist is expected to have a basic knowledge of pharmacology to prepare and administer drugs under the supervision of a licensed practitioner. The PDR is a reference, usually found in the radiology department, that lists drugs by both generic and trade names. Some common dosage forms include tablets, capsules, suppositories, solutions, suspensions, and transdermal patches. The radiologic technologist should be familiar with the actions and precautions associated with commonly used drugs. The golden rules of drug administration should always be followed when preparing to administer or when assisting with drug administration. Numerous factors affect the patient’s response to a drug, which may be undesirable. After administration, relevant information should be recorded on the patient’s chart. Copyright © 2012, 2007, 2002, 1997, 1991, 1984, 1979 by Saunders, an imprint of Elsevier Inc. All rights reserved. 26 9