Foundations and Principles of Pharmacology Chapter 4 Foundations and Principles of Pharmacology

Chapter 4 Lesson 4.1

Learning Objectives Define the key words used in pharmacology and medication administration Explain differences between the chemical, generic, official, and brand names of medicines List the basic types of drug actions Describe the four basic physiologic processes that affect medications in the body

Overview Pharmacokinetics Pharmacodynamics Pharmacotherapeutics Box 4-1: Key Words Used in Pharmacology and Drug Administration Pharmacokinetics: what the body does to the drug Pharmacodynamics: what the drug does to the body Pharmacotherapeutics: the use of drugs in the treatment of disease Can you think of a drug you may have used to produce a specific effect in the body? (Example, acetaminophen for fever/pain reduction)

Drug Names Generic name Trade name; ® symbol Chemical name Official name Generic names are the same in all countries and are not capitalized when written. What is the trade name for acetaminophen? Chemical names are the most difficult to remember and also include the chemical that make up the drug. The official name, often assigned by the Food and Drug Administration (FDA), may be similar to the brand or chemical name. The first letter of the name is always capitalized.

Types of Drug Actions Drug attachment Receptor sites Drugs attach to a receptor site within the body and form a chemical bond. Chemical reactions between a drug and a receptor site are only possible when they fit together like pieces of a jigsaw puzzle or a key in a lock. If the drug fits the receptor site well, the chemical response is generally good; how good it is determines the drug’s efficacy.

Drug Receptor Sites

Drug Attachment Agonist Antagonist Partial Agonist Drugs known as agonists attach at the receptor site and activate the receptor, producing an action similar to that of the body’s own chemicals. What type of action occurs when the drug attaches to a site but produces only a small chemical response? What happens when an antagonist drug attaches to a receptor site? Some partial agonists and antagonists are able to compete with other chemicals or drugs already bonded to a receptor site and replace them.

Basic Drug Processes Absorption Distribution Metabolism Excretion Drugs have to undergo certain chemical changes to be utilized by the body. Drugs have different characteristics (pharmacokinetics) that determine to what extent the basic processes will be used. Can you think of any illnesses or conditions that may alter basic drug processes?

Four Processes of Drug Utilization

Absorption How a drug enters the body and passes into body fluids and tissues Absorption processes: Diffusion—high concentration to lower concentration Filtration—a filter prevents passage of certain molecules Osmosis—diffusion through a semipermeable membrane from a less dense solution to a more dense solution What factors determine how fast the drug is absorbed into the body? If the drug action is needed immediately, what route is used? If the nurse massages the tissue around an injection site after the drug is injected, will this increase or decrease drug absorption? Why?

Diffusion

Filtration

Osmosis

Distribution Blood system Lymph system Barriers: Blood-brain Placental Why do drugs have difficulty passing through the blood-brain and placental barriers? Can you determine what advantages these natural barriers provide?

Metabolism Biotransformation First-pass effect Affected by genetic and developmental factors Can you identify some clinical conditions that may alter drug metabolism? Would the dosage of a drug administered orally be larger or smaller if that same drug were administered intravenously? Can you identify the term used to describe drugs that are toxic to the kidneys?

Excretion GI tract Kidneys Lungs Skin Identify populations within the lifespan that are at higher risk for impaired elimination or excretion of drugs. If drugs are not eliminated adequately, what clinical condition may occur? Why should a mother who is breastfeeding check with her healthcare provider before taking any drug?

Chapter 4 Lesson 4.2

Learning Objectives Discuss the differences between side effects and adverse affects List the basic types of drug actions

Basics of Drug Action Desired action Adverse reactions Idiosyncratic reactions How do drug side effects differ from adverse effects? What is the term used to describe a drug reaction opposite to that expected? How does an allergic reaction differ from an anaphylactic reaction? Idiosyncratic (paradoxical) reactions are most common in pediatric and geriatric populations.

Bioequivalence Define Brand name versus generic Generic equivalent What is the term used to describe drug products, brand and generic, that are chemically similar? Is it acceptable for the pharmacist to dispense a generic drug rather than a brand-name drug? Which drugs should be dispensed exactly as the prescriber has written them?

Drug Interactions Drug action may depend on ability to dissolve quickly or slowly Controlled by medication form Oil-based drugs Liquid/solutions are more soluble than capsules, which must dissolve their outer coating first. Oil-based injections must be chemically changed first before absorption can occur. Can you think of other things that may affect absorption? Why should the nurse be concerned when combining two different drugs in a syringe? The use of alcohol and sedatives may produce what type of drug interaction?

Food, Alcohol, and Drug Interactions Food interactions Alcohol interactions Drugs and laboratory tests Chronotherapy Why is there an increased risk for drug–alcohol interactions when oral drugs are given? What foods would you advise a patient taking MAOIs to avoid? What effect does cigarette smoking have on the metabolism of drugs? Why is chronotherapy significant for nurses? What are some examples of medications and conditions affected by chronotherapy?