Chapter_002.pptx

Chapter 2 Pharmacologic Principles Overview  Drug   Any chemical that affects the physiologic processes of a living organism Pharmacology   Study or science of drugs Encompasses a variety of topics 2 Drug Names Chemical name  Describes the drug’s chemical composition and molecular structure Ge...

Chapter 2 Pharmacologic Principles Overview  Drug   Any chemical that affects the physiologic processes of a living organism Pharmacology   Study or science of drugs Encompasses a variety of topics 2 Drug Names Chemical name  Describes the drug’s chemical composition and molecular structure Generic name (nonproprietary name)  Name given by the United States Adopted Names Council Trade name (proprietary name)  The drug has a registered trademark; use of the name is restricted by the drug’s patent owner (usually the manufacturer). 3 Drug Classifications Drugs are grouped together based on similar properties  Drug classifications   Structure (ex. beta blocker) Subclass (ex. selective, nonselective) Therapeutic use (ex. antibiotic) Subclass (ex. penicillins) Prototypical drugs: first drug in a class of drugs 4 Pharmacologic Principles         Pharmaceutics Pharmacokinetics Pharmacodynamics Pharmacogenomics (pharmacogenetics) Pharmacotherapeutics Pharmacognosy Pharmacoeconomics Toxicology 5 Definition of Pharmaceutics   The study of how various drug forms influence the way in which the drug affects the body. Dissolution—dissolving of solid dosage forms and their absorption 6 Audience Response System Question #1 A patient is prescribed ibuprofen 200 mg PO every 4 hours as needed for pain. The pharmacy sends up enteric-coated tablets, but the patient refuses the tablets, stating that she cannot swallow pills. What will the nurse do? A. Crush the tablets and mix them with applesauce or pudding. B. Call the pharmacy and ask for the liquid form of the medication. C. Call the pharmacy and ask for the IV form of the medication. D. Encourage the patient to try to swallow the tablets. NOTE: No input is required to proceed. 7 Answer to System Question #1 ANS: B The liquid form is appropriate because it is also given via the oral route. Enteric-coated tablets should not be crushed, and the patient should not be forced to take the tablets. This medication does not have an IV form, but even if it did, the routes cannot be changed without a health care provider’s order. 8 Definition of Pharmacokinetics  The study of what the body does to the drug     Absorption Distribution Metabolism Excretion 9 Definition of Pharmacodynamics  The study of what the drug does to the body  Drug-receptor relationships 10 Definition of Pharmacotherapeutics    The clinical use of drugs to prevent and treat diseases Defines principles of drug actions—the cellular processes that change in response to the presence of drug molecules Drugs are organized into pharmacologic classes. 11 Definition of Toxicology  Science of the adverse effects of drugs and other chemicals on living organisms 12 Definition of Pharmacognosy  The study of natural (versus synthetic) drug sources (i.e., plant, animals, minerals) 13 Definition of Pharmacoeconomics   Study of the economic factors influencing the cost of drug therapy Cost–benefit analysis 14 Pharmaceutics    Different drug dosage forms have different pharmaceutical properties. Dosage form determines drug dissolution rate. See Table 2-1 for a listing of various oral drug forms and their dissolution rates 15 Enteral Route  The drug is absorbed into the systemic circulation through the oral or gastric mucosa or the small intestine.     Oral Sublingual Buccal Rectal (can also be topical) 16 Parenteral Route        Intravenous (fastest delivery into the blood circulation) Intramuscular Subcutaneous Intradermal Intraarterial Intrathecal Intraarticular 17 Audience Response System Question #2 The nurse is preparing to administer a transdermal patch to a patient and finds that the patient already has a medication patch on his right upper chest. What will the nurse do? A. Remove the old medication patch and notify the health care provider. B. Apply the new patch without removing the old one. C. Remove the old patch and apply the new patch in the same spot. D. Remove the old patch and apply the new patch to a different, clean area. NOTE: No input is required to proceed. 18 Answer to System Question #2 ANS: D Transdermal drugs should be placed on alternating sites, on a clean and nonirritating area, and only after the previously applied patch has been removed. 19 Topical Route        Skin (including transdermal patches) Eyes Ears Nose Lungs (inhalation) Rectum (for local effects) Vagina 20 Pharmacokinetics  Absorption   Bioavailability The extent of drug absorption First pass effect Large proportion of a drug is chemically changed into inactive metabolites by the liver. Much smaller amount will be bioavailable.  Distribution   Transport of a drug by the bloodstream to its site of action Albumin is the most common blood protein and carries the majority of protein-bound drug molecules. 21 Pharmacokinetics (Cont.)  Metabolism Also referred to as biotransformation Biochemical alteration of a drug into an inactive metabolite, a more soluble compound, a more potent active metabolite (as in the conversion of an inactive prodrug to its active form), or a less active metabolite. 22 Pharmacokinetics (Cont.)  Metabolism (cont.) Cytochrome P-450 enzymes (or simply P-450 enzymes), also known as microsomal enzymes Lipophilic: “fat loving” Hydrophilic: “water loving” Enzymes Prodrugs 23 Pharmacokinetics (Cont.)  Excretion Elimination of drugs from the body Renal excretion (primary organ responsible for excretion) Biliary excretion Bowel excretion 24 Pharmacokinetics (Cont.)  Half-life: time required for half (50%) of a given drug to be removed from the body  Measures the rate at which the drug is eliminated from the body  After approximately five half-lives, most drugs are considered to be effectively removed from the body.  Steady state Physiologic state in which the amount of drug removed via elimination is equal to amount of drug absorbed with each dose. 25 Pharmacokinetics (Cont.) Drug Effects   The length of time for onset, peak of action and the duration of action play an important part in determining the peak level (highest blood level) and trough level (lowest blood level) of a drug. If the peak blood level is too high, then drug toxicity may occur. 26 Pharmacokinetics (Cont.)     Peak level: highest blood level of a drug Trough level: lowest blood level of a drug Toxicity: occurs if the peak blood level of the drug is too high Therapeutic drug monitoring 27 Audience Response System Question #3 The nurse is giving a medication that has a high first-pass effect. The health care provider has changed the route from PO to IV. What can the nurse expect with the IV dose? A. B. C. D. The IV dose will be higher because of the first-pass effect. The IV dose will be lower because of the first-pass effect. The IV dose will be the same as the PO dose. The rate of IV infusion must be faster due to first-pass effect. NOTE: No input is required to proceed. 28 Answer to System Question #3 ANS: B The first-pass effect is the metabolism of a drug before it becomes systemically available, and it reduces the bioavailability of the drug. This primarily occurs with oral medications. Therefore, IV doses need to be lower than PO doses because of the first-pass effect. 29 Pharmacodynamics  The study of what the drug does to the body      The mechanism of drug actions in living tissues Therapeutic effect Drug–receptor relationships Enzymes Nonselective Interactions 30 Audience Response System Question #4 A patient is complaining of severe pain and has orders for morphine sulfate. The nurse knows that the route that would give the slowest pain relief would be which route? A. B. C. D. IV IM Subcutaneous PO NOTE: No input is required to proceed. 31 Answer to System Question #4 ANS: D Parenteral routes result in the fastest absorption and therefore also the fastest effects. Oral administration is the slowest. 32 Pharmacotherapeutics    The clinical use of drugs to prevent and treat diseases Defines principles of drug actions—the cellular processes that change in response to the presence of drug molecules Drugs are organized into pharmacologic classes. 33 Pharmacotherapeutics (Cont.)         Contraindications Acute therapy Maintenance therapy Supplemental (or replacement) therapy Palliative therapy Supportive therapy Prophylactic therapy Empiric therapy 34 Pharmacotherapeutics (Cont.)        Monitoring Therapeutic action Adverse effects Cumulative effects Therapeutic index Drug concentration Patient condition 35 Pharmacotherapeutics (Cont.)     Tolerance: decreasing response to repeated drug doses Dependence: physiologic or psychological need for a drug Physical dependence: physiologic need for a drug to avoid physical withdrawal symptoms Psychological dependence: also known as addiction and is the obsessive desire for the euphoric effects of a drug 36 Pharmacotherapeutics (Cont.)  Drug interactions     Additive effects (1 + 1 = 2) Synergistic effects (1 + 1 > 2) Antagonistic effects (1 + 1 < 2) Incompatibility 37 Pharmacotherapeutics (Cont.)  Adverse drug event (ADE)   Medication error Adverse drug reaction 38 Pharmacotherapeutics (Cont.)  Medication use process in which errors can occur:     Prescribing Dispensing Administering Monitoring 39 Pharmacotherapeutics (Cont.)  Adverse drug reactions:  Pharmacologic reaction  Hypersensitivity (allergic) reaction  Idiosyncratic reaction  Drug interaction 40 Pharmacotherapeutics (Cont.)  Other drug effects  Teratogenic  Mutagenic  Carcinogenic effects 41 Pharmacognosy  Four main sources for drugs:     Plants Animals Minerals Laboratory synthesis 42 Pharmacoeconomics   Cost-benefit analysis Examine treatment outcomes in relation to the comparative total costs of treatment with drug(s) 43 Toxicology     Science of adverse effects of chemicals on living organisms Clinical toxicology: Care specifically to the poisoned patient Poison Control Centers Treatment based on system of priorities   ABCs Prevent absorption of the toxic substance and/or speed its elimination from the body 44 Summary   Thorough understanding of pharmacologic principles is essential for safe, quality nursing practice. Application of principles enables the nurse to provide safe and effective drug therapy. 45