NUR 320 Module 1B Pharmacology PDF

NUR 320 MODULE 1B Introductory Topics for Pharmacology Mary Rose Gaughan, PhD, RN, CNE D’Youville University PRESENTATION TITLE 1  MODULE 1B Agenda Terminology and guidelines for interpretation and transcription of dru...

NUR 320 MODULE 1B Introductory Topics for Pharmacology Mary Rose Gaughan, PhD, RN, CNE D’Youville University PRESENTATION TITLE 1  MODULE 1B Agenda Terminology and guidelines for interpretation and transcription of drug orders Legal and ethical implications related to drug administration Principles of drug action Development and cultural (ethnic) considerations 2  MODULE 1B Today’s Objectives Describe the concepts and principles of drug action. Identify developmental and cultural considerations of pharmacology and drug administration. Understand terminology and guidelines related to pharmacology. 3  MODULE 1B Pharmacology The study of biological effects of chemicals Drugs are chemicals that are introduced to the body to cause a change Herbals or non-pharmaceuticals can also cause changes to the body Pharmacotherapeutics uses drugs to prevent, diagnose, or treat disease processes Pharmacotherapy uses drugs to prevent, diagnose, or treat symptoms and disease processes 4 What does this mean to nursing practice? Nursing guidelines require safe practice when administering medications Drugs can have many effects – some helpful, some undesirable or harmful Responsibilities include: administration of drugs, assessing drug effects, intervening to make the drug regimen more tolerable, providing patient teaching, monitoring the overall care plan to prevent medication errors 5 Sources of Drugs Natural Synthetic Plant Genetic engineering Animals Improving established medications Inorganic compounds 6 Classification of Drugs Classified according to effects on a particular body system, therapeutic use, and chemical characteristics Drugs fit into many groups because of their effects on the human body Example: morphine – CNS depressant and an opioid analgesic 7  MODULE 1B Prototype Often the first drug of the class to be developed The standard to which newer drugs are compared to Example: Morphine is the prototype analgesic Some groups lack a universally accepted prototype Some prototypes are replaced over time with newer, more commonly utilized drugs 8  Generic Brand Name Related to the Also known as chemical or official ‘Trade Name’ name Designated and Independent of patented by the manufacturer manufacturer Presented in Presented with a lowercase letters capital letter US Adopted Names Most need to be Council assigns ordered “dispense generic name as written” or “do Required to be not substitute” therapeutically equivalent and less expensive than brand name Monitored by FDA 9 Drug Evaluation U.S. Food and Drug Administration (FDA) Tight control Regulates development and sale of drugs Ensures safety and reliability of drugs Several stages of development to determine if benefits outweigh the known and potential risks of the medication Pre-clinical trials, phase I, II, and III studies Orphan drugs – discovered but not financially viable, have not been ‘adopted’ by a drug company May be useful in treating rare disease or have potentially dangerous adverse effects MODULE 1B 10  FDA Trials and Studies Pre-clinical Trials Do not use humans (use animals) Initial Testing Determine whether drug has presumed effects in living tissue Evaluates adverse effects Phase I Studies Human volunteers to test drugs for safety and dosage information Healthy volunteers with the condition medication is designed to help Informed of potential risks and must sign consent Phase II Studies More patients who have the disease drug is designed to treat Performed across the country Drug may be removed from testing is it has unacceptable adverse effects Phase III Studies Larger sample of population Determine treatment benefit and monitor side effects not apparent in earlier studies Participants keep journals and record symptoms FDA Approval Phase IV Continual evaluation after approval for marketing MODULE 1B 11 FDA Labels and “Off-Label” Uses Prescribing information from studies is refined and “labelled” Label lists the approved uses, risks and benefits of medication based on clinical trials “Off label” – uses of a drug that are not part of stated therapeutic indications for which the drug was approved 12 Legal Regulation of Drugs FDA regulates the development and sale of drugs Local laws further regulate the distribution and administration of drugs Vary from state to state, can also vary within a state Federal legislation affects the clinical use of drugs 13 Safety in Pregnancy Category A: Adequate studies not demonstrated a risk to the fetus in any study Category B: Animal studies have not demonstrated a risk to the fetus, but there are no adequate studies in pregnant people, or animal studies have shown an adverse effect. Category C: Animal studies have shown an adverse effect on the fetus, but there are no adequate studies in humans; the benefits from the use of the drug in pregnant people may be acceptable despite its potential risks, or there are no animal reproduction studies and no adequate studies in humans. Category D: There is evidence of human fetal risk, but the potential benefits from the use of the drug in pregnant people may be acceptable despite its potential risks. Category X: Studies in animals or humans demonstrate fetal abnormalities or adverse reactions 14 Controlled Substances Schedule I (C-I): High abuse potential and no accepted medical use (heroin, LSD) Schedule II (C-II): High abuse potential with severe dependence liability (narcotics, amphetamines, and barbiturates) Schedule III (C-III): Less abuse potential than schedule II drugs and moderate dependence liability (nonbarbiturate sedatives, nonamphetamine stimulants, limited amounts of certain narcotics) Schedule IV (C-IV): Less abuse potential than schedule III and limited dependence liability (some sedatives, antianxiety agents, and nonnarcotic analgesics) Schedule V (C-V): Limited abuse potential. Primarily small amounts of narcotics (codeine) used as antitussives or antidiarrheals. 15 Sources of Drug Information Drug labels Name, dosage, expiration date, warnings Package inserts By manufacturer according to FDA regulations Contains ALL chemical and study information Most accurate source – continually updated Reference books Package insert compilation Numerous on the market Journals New drugs/classes, specific treatment protocols Internet information Must be reliable Government and association websites MODULE 1B 16  Pharmacodynamics Study of interactions between the MODULE 1B chemical components of living systems and the foreign chemicals, including drugs, that enter the system Drugs work in one of four ways: 1) Replace or act as substitutes for missing chemicals 2) Increase or stimulate certain cellular activities 3) Depress or slow cellular activities 4) Interfere with the functioning of foreign cells, such as invading microorganisms or neoplasms that cause cell death 17 Receptor Sites MODULE 1B Specific areas on cell membranes that react with certain chemicals to cause an effect within the cell “Lock and key” Key = specific chemical Lock = receptor site Receptor Site Interactions Agonist: Binds to a receptor site and produces an effect Prevent the breakdown of natural chemicals that stimulate the receptor site Competitive Antagonist: React with receptor sites to block normal stimulation Noncompetitive Agonists: Prevent reaction of another chemical with a different receptor site on that cell. 18 Receptor Sites 19  Drug-Enzyme Interactions Drugs can cause their effect by interfering with the enzyme systems that act as catalysts for various chemical reactions. Enzyme systems work in a cascade fashion, with one enzyme activating another. Then that enzyme activates another. 20 Selective Toxicity MODULE 1B Ability of a drug to attack only those systems found in foreign cells This is the ideal situation Example: penicillin affects enzyme system unique to bacteria = bacterial death 21 Pharmacokinetics MODULE 1B The study of how medications travel through the body Absorption Distribution Metabolism (biotransformation) Excretion In clinical practice the nurse must consider: Onset of drug action Drug half-life Timing of peak effect Duration of drug effects Metabolism of the drug Site of excretion 22 Critical Concentration and Therapeutic Index Critical Concentration: Therapeutic index = amount of drug need Loading dose – ratio of blood to cause a therapeutic higher dose than concentration where effect usual allowing the the drug becomes drug to reach critical toxic to the concentration concentration at sooner which the drug is effective ex: Heparin 23  MODULE 1B Absorption Time from when drug is introduced to the body until it reaches circulating fluids and tissues Several sites of absorption - route influences rate and amount absorbed (Table 2.1) IV is the fastest, bypasses barriers of oral absorption PO is non-invasive and usually less expensive Some drugs chemically unstable or not absorbed well PO must be given by injection (example: insulin) Intramuscular injections may be influenced by decreased blood flow to the tissues and muscles. Absorption may be influenced by intestinal issues 24  PRESENTATION TITLE Distribution Movement of drug into body tissues Circulation, permeability of cell membrane, and plasma protein binding all contribute Protein binding = bound to proteins in blood to be carried into circulation If tightly bound = long duration of action Loosely bound = act quickly, excreted quickly NOT available when they are bound Blood-brain barrier – only lipid soluble drugs can pass, protective mechanism for the brain 25 Biotransformation (Metabolism) Liver is the most important site of metabolism  changes drugs into new chemicals First-Pass Effect – drugs taken by mouth have potential for a large percentage to be destroyed PO drugs absorbed in GI, transported to liver, metabolized Drug that makes it through first pass effect is delivered to circulatory system for transport Injected drugs often have a lower dose because of first-pass effect Patients with hepatitis may have impairment with drug metabolism 26  MODULE 1B Biotransformation (Metabolism) Hepatic Enzyme System – biotransforms drugs CYP-450  Found in most cells, abundant in liver Drugs can increase or decrease activity of CYP-450 Affects the metabolism of other drugs Sub-therapeutic drug levels Toxicity Liver disease – if not functioning properly drugs not metabolized correctly = toxicity Influenced by grapefruit juice, many other drugs/herbals 27  MODULE 1B Excretion Kidneys play the most important role Blood Urea Nitrogen (BUN) and creatinine (Cr or Crea) monitored to evaluate kidney function Drugs made water soluble during metabolism readily excreted by kidney, others secreted or reabsorbed Kidney dysfunction can lead to toxicity because it cannot be excreted 28 Pharmacokinetics Recap 29 Half-life The time it Important for takes for the dose amount of drug scheduling and in the body to duration of decrease to drug’s effect on one half of its the body peak level Shorter half-life Liver and = leaving the kidney body quicker, dysfunction needs more can lengthen frequent dosing half-life 30 Factors Influencing Drug Effects Interactions Weight When two or more drugs/substances taken Age together Sex Can produce serious adverse effects Physiological factors Can occur during absorption, distribution, Pathological Factors metabolism, excretion, or at the site of action Genetic Factors Immunological Factors MUST ensure patient safety – consult drug guide Psychological Factors for potential interactions Environmental Stagger administration or contact provider if Drug Tolerance necessary Accumulation Effects Take measures to improve any discomfort Interactions associated with adverse effects 31 Adverse Effects Undesired effects that may be unpleasant or even Primary actions of the drug can be extensions of the desired effect Secondary actions of the drug are effects that the drug causes in the body that are not related to the therapeutic effect. The nurse checks for adverse effects following drug administration. Drug allergies or hypersensitivity can often occur when a patient develops antibodies to a drug after exposure to the drug 32  Dermatological reactions (complication) Drug Induced Rashes and hives to Stevens-Johnson syndrome Tissue & Organ (potentially fatal) Damage Stomatitis (inflammation of mucous membranes) GI Irritation Nausea, vomiting, constipation, diarrhea, heartburn, bloating Superinfection Destruction of normal flora leads to superinfection of organisms usually controlled by normal flora Example: C.Diff Blood Dyscrasia Bone marrow suppression by drug effects MODULE 1B 33 Toxicity Liver cells exposed to full impact of drug (first pass effect) Hepatotoxicity Irritation from metabolites Renal vasoconstriction, direct tubular damage, intratubular obstruction, or combination Nephrotoxicity Active forms and metabolites can damage nephron- decrease urine output Aging processes affect drug interactions Poisoning Overdose that damages multiple body systems 34  MODULE 1B Alterations in Glucose Metabolism Hypoglycemia Low glucose in the blood Some anti-diabetic agents lower blood sugar too much Hyperglycemia High glucose in the blood Corticosteroids increase insulin resistance in the liver = elevated blood sugar 35 Electrolyte Imbalances Hypokalemia Altering renal exchange system can cause Example: loop diuretics potassium loss Potassium retention and increasedHyperkalemia serum Cell death = K+ release hyperkalemia K+ Example: anti-neoplastic drugs Example: Potassium sparing diuretics Other imbalances: hypercalcemia, hypocalcemia, hypernatremia, hyponatremia, hypermagnesemia, hypomagnesemia 36  MODULE 1B Sensory Effects Ocular Damage End arteries in the retina can have drug deposits that cause inflammation and tissue damage Can lead to blindness Auditory Damage Tiny vessels and nerves in the eighth cranial nerve easily irritated and damaged by certain drugs Auditory ringing (tinnitus) antibiotics can cause progressive hearing loss 37 Neurological Effects Neuroleptic General CNS Anticholinergic Extrapyramidal Malignant Effects Effects Symptoms Syndrome Alterations in Blockage of Dopamine levels General electrolyte and cholinergic affected = anesthesia can glucose levels receptors Parkinsonian cause CNS stimulants Many cold symptoms High fever, can or depression remedies and Antipsychotic be fatal anti-histamines and neuroleptic can cause drugs can cause 38 Teratogenicity Drugs that reach developing fetus or embryo can cause death and congenital defects Defects include skeletal or limb abnormalities, CNS alterations, heart defects Benefits should outweigh risks 39  MODULE 1B Nursing Process Assessment, nursing conclusions, planning, intervention, evaluation; obtain medication history Application of the nursing process ensures safe, efficient, scientifically based, quality, holistic care When a medication is given you must follow your ‘Rights’ and complete appropriate follow- up care If you are not familiar with a medication look it up-obtain information 40  MODULE 1B Comfort Measures Placebo effect The anticipation that a drug will be helpful Managing Adverse Effects Promote patient safety and decrease impact of anticipated adverse effects Lifestyle adjustment Changes in lifestyle due to medications and their effects Altering activities or diet may be necessary Can have a tremendous impact 41 Patient and Prevents medication errors Family Education Drug education needs to include: Name, action, dose of drug Timing of administration Special storage or preparation instructions Specific OTC drugs/alternative therapies to avoid Special comfort measures Safety measures Specific points about toxicity – give them warning signs Specific warnings about drug discontinuation MODULE 1B 42 Medication Errors The Nurse’s Role The Patient’s Role The ‘rights’ of administration Keeping an accurate record of all Right patient medications (Rx, OTC, and herbal) Right drug Know what each drug is being used to treat Right storage Read the labels, follow directions Right route Right dose Store drugs in a dry place, away from children and pets Right preparation Speak up! Ask questions! Right time Right recording Never use adult medications to treat a child Encourage patient autonomy and Measure using appropriate devices advocacy Call your HCP with questions or Provide health teaching concerns Reporting Medication Errors Must be reported on national and institutional level; Report according to the policy of the health care facility. Reports compiled to prevent error reoccurrence Prompt the issuing of HCP warnings – point out potential or actual medication errors, suggest how to avoid in the future Reporting medication errors Always be aware of institutional Identifying areas for educational or systemic policies change 44