NUR 104 Module A Introduction to Pharmacology

NUR 104 Module A Introduction to Pharmacology

Ch. 1 Orientation to Pharmacology • Scientific study of all aspects of drugs, including their source, properties, uses, actions and effects within a living system • Deals with legal/illegal drugs used today – includes street, prescription, nonprescription (OTC) • More drugs have lead to an improved quality of life & longer life span

Nurses are professionally, morally, legally, and personally responsible for every dose of medication they administer.

Sources of Medications • • Plants Animals Minerals Synthetics

Nurses must know before giving meds the usual dosage, route of administer, indications, significant side effects/adverse reactions, major drug interactions, contraindications, & appropriate nursing assessment, planning, implementation & evaluation techniques necessary to administer the drug safely.

INFORMATION • Hospital/Pharmacy Resources PDR Physicians’ Desk Reference Hospital Formulary Facts and Comparisons • Package Inserts

Drug Names • Chemical – description of composition & structure – rarely used in clinical practice. N-acetyl-para-aminophenol • Generic /Nonproprietary – name given by manufacturer, listed in official publications. Acetaminophen • Trade /Brand/Proprietary – name under which manufacturer makes med. Tylenol

• Drugs are also described as either 1) Prescription or legend drug 2) Non-prescription (Over-the-counter) OTC Some prescription drugs sold in lower doses OTC

Classification • Medications with similar actions are grouped together. e. g. Anti-hypertensive • Indicates effect on body system, symptom relieves, or desired effect (clinical indication) • Example – aspirin is an analgesic, antipyretic, and an anti-inflammatory

CH. 2 Legalities of Med. Adm.

Drug Standards • No legal control of meds. until early 1900 s with Pure Food & Drug Act 1906 (all meds to be free of impure products) • Designated the United State Pharmacopeia and the National Formulary as official standards and empowered the federal government to enforce them • 1912 – Congress passed Sherley Amend. – prohibited fraudulent therapeutic claims

• 1938 –Food, Drug, & Cosmetic Act – drugs must be tested for harmful effects before marketing and labels must be accurate (FDA established) • 1962 – Kefauver-Harris Act – tightened controls over drug safety (thalidomide) safety/efficacy • 1983 – Orphan Drug Act – FDA could provide grants to drug researchers for research for tx of rare chronic diseases

Controlled Substance Laws • Harrison Narcotic Act of 1914 – legally classified meds that were habit forming as narcotics, regulated sale, manufacture, use • Controlled Substance Act of 1970 – set strict controls (unlawful without prescription); set up programs for prevention and treatment of dependency, classified controlled substances into schedules. 1973 –DEA sole legal drug enforcement agency in US

Five Schedules (pg 15) • I – only research (heroin, LSD, marijuana) high abuse potential • II – high potential for abuse, no telephone prescriptions, no refills (morphine, cocaine, Demerol. Dilaudid, Codeine); in-house PRN must be re-written after 3 days, ordered routine after 7 days

Schedules - continued • III – lower abuse potential, telephone orders OK – rewritten q 6 months or 5 refills ( aspirin or Tylenol with codeine, hydrocodone) • IV – similar to III except for penalties for illegal possession (talwin, darvon, Librium, valium BZDs) • V – low abuse potential, may be sold OTC, must sign with pharmacist cough, diarrhea (Lomotil)

New/Experimental Drugs • • • New drugs are approved through FDA First animal studies, then human studies 3 phase process with human studies Only volunteers used Informed consent obtained in writing (Participants protected under Nuremberg Code) • Double-blind studies

Pregnancy Safety Categories • A – adequate animal & human studies, no risk • B – no risk in animals, no well-controlled studies in women • C – animal studies show adverse affects on fetus, no studies in humans • D – evidence of human fetal risk but benefits may outweigh risks • X – risks outweigh benefits

Nursing practice regulated by: • Drug standards & legislation • Nurse Practice Act • Policy statements from nursing, medical & hospital associations • Institutional policy & procedures

• In the past, drug administration done by physicians • However, today, nurses are responsible for all types of drug administration including Intravenous meds • In 1998, nurse practitioners were given prescriptive abilities in all 50 states

AVOIDING MEDICATION ERRORS HOW? List p. 29

• Clarify the physician’s order (TO, VO, read order correctly) • Be accountable for actions • Know limitations • Adhere to the Rights of Medication Administration

Seven Rights of Medication Administration

Ch. 3 Principles of Drug Action

Processes Mediating Drug Action (Pharmacokinetics) • • Absorption Distribution Metabolism Excretion Usually controlled by passive transport (diffusion)-moving from higher to lower conc. and active transport.

Absorption – movement of drugs from their site of administration into vascular bed. Affected by many things. • Solubility – ability to dissolve & form a solution in body fluids. Lipid-soluble products enter vascular system more readily because cell membranes contain a fatty acid layer.

• Dosage Form. Pharmaceutical processing – binders used in manufacturing. Alcohol increases, starch & oils decrease. Capsules, tablets, liquids, extended release • p. H – nonionized /lipid-soluble, diffusible ionized/water soluble, nondiffusible (pg 36) • acidic vs. basic drugs • Route of Administration- enteral, parenteral, topical, pulmonary

• Food – presence of food decreases emptying time & increases med contact with digestive juices. Empty stomach increases absorption • Circulation to site – increased blood flow increases med absorption • Absorbing surface – larger surface area, greater absorption e. g. small intestine • Drug concentration -increased concentration, increased absorption Loading dose Maintenance dose

Medications Preparations Medications are administered for either a local or systemic effect LOCAL – effects are confined to one area of the body SYSTEMIC – medications is absorbed and delivered to body tissues by the vascular system

LOCAL EFFECTS • Generally applied to skin (topically), mucous membranes, or joint cavity (injection) Astringents, emollients, cleansing agents, anesthetics, antiseptics, antibiotics, anti-inflammatory, fungicides

Systemic Effects • Absorbed into vascular system, carried through body and affect one or more body systems Orally, topically, parenterally, mucous membranes

Routes of Administration • Oral – most common, usually safest, giving water often increases absorption • Parenteral – IV, IM, SQ, intradermal, must be sterile. Intrathecal, Epidural • Mucous membrane – SL, buccal, inhalation, vaginal, rectal • Topical – dermal, transdermal, ophthalmic, otic

Distribution – transport of drug in body fluids from bloodstream to body tissues & site of action • After med is absorbed, distribution depends on cardiac output and regional blood flow • Drug pooling or storage of med pg 35 Figure 3 -3 • 1) Plasma Protein Binding • Transported by protein molecules (albumin), the stronger the binding to protein, slower freeing, therefore longer duration of action – pt. with hypoalbuminemia has difficulty transporting meds

• 2) Tissue Binding Fat e. g. IM Injections Bone e. g. Tetracycline

Metabolism or Biotransformation Process of chemically inactivating a drug by converting it into a more water-soluble compound that can be excreted from body

• Occurs in the liver, kidneys, lungs, plasma • “Hepatic first-pass effect” – Oral meds absorbed from the GI tract normally travel first to the venous system of the liver. A significant amount of the drug is metabolized ( on the first pass) before ever reaching the systemic circulation. Oral doses of some meds have to be higher than parenteral. Parenteral meds by-pass liver. The young and elderly do not have fully functioning liver enzymes – may affect drug levels.

Excretion – elimination from body • Most are eliminated through renal system (also liver, lungs, sweat and salivary glands, mammary glands, dialysis) • Clearance – speed at which drug leaves body through kidneys. Biologic half-life – amount of time required for plasma concentration of drug to decrease 50% affects how often a drug is administered

• Kidney usually removes med that is unbound and free in plasma, correlated with creatinine clearance, some totally excreted on 1 st pass through kidney • GI system – unabsorbed oral meds • Pulmonary – gases (anesthetic agents), alcohol

Pharmacodynamics • The effect the drug has on the body.

Agonist – acts like receptor and drug action occurs (like) Antagonistic • Opposite action • Combined effect is less than either alone • Antidote

Mechanism of Action 1) Drug-Receptor Interaction • KEY---is the drug or drug and cellular enzyme • LOCK- is a specific part of the cell

2. Non-Receptor Drug Theory Chemical Molecular structure of drug is changed altering properties, may be beneficial Ex. Protamine sulfate (weak anticoagulant) is given to stop activity of heparin (anticoagulant). Together they form bond with no anticoagulant activity. Harmful – multivitamins/antibiotics in same IV changes p. H & inactivates antibiotic

Drug-Response Relationship • Let’s look at plasma level profile of a sample med. Page 45 Figure 3 -7

Terms to Know, pg 45 • Onset of Action • Peak plasma level • Duration of Action • Minimal Effective Concentration • Toxic Level • Therapeutic Range

Biologic Half-Life • The time required to reduce by half the amount of unchanged drug in the body at the time equilibrium is established. • Does not change with dosage…… • If it takes 30 min. to eliminate half of the drug, it still takes thirty minutes to eliminate half of the drug.

Factors Affecting Response • • Weight/Body Mass Age Diet/nutrition Time of Administration Ethnic origin Genetics Pathological and Psychological state Pre-existing disease

Side Effects/Adverse Reactions

• Side effects -usually a predictable and many times unavoidable secondary effects produced by drug at usual therapeutic drug doses. Ex. – narcotic (opioid) analgesic often causes side effect of drowsiness & constipation • Occurs at the usual prescribed dose • Intensity of side effects often dose dependent

Adverse reaction –side-effect – potential unwanted effects pt experiences. Ranges from those which are uncomfortable but tolerated (nausea, dizziness) to those that are life threatening = seizures, cardiac arrest These reactions may be acute or delayed

Types of Adverse Reactions • Predictable– 70 -80% of all adverse reactions, dose dependent, often preventable & predictable: affected by age, body mass, sex, environment, time of adm, genetics • Unpredictable– immunologic or idiosyncratic, not dose dependent, usually not preventable or predictable

Predictable Adverse Reactions • Primary – most adverse or toxic events are expected extensions of drug’s known actions. Excessive drowsiness from sedatives, hypotension from antihypertensives – overdoses may occur • Secondary – antihistamines – sleepiness, tiredness/impotence from antihypertensives, may need to decrease or discontinue dose

Unpredictable Adverse Reactions • Allergic – hypersensitivity range from mild (urticaria) to severe life-threatening, may just be an adverse reaction. Can be immediate or delayed reactions. Anaphylactic reaction, antigen-antibody, autoimmune reactions • Idiosyncratic – unexpected, abnormal, usually associated with genetic defect, hyperthermia after general anesthesia

Drug Interactions Action of drug is modified in or on body by another chemical, drug, diet or environment

Incompatibility Chemical or physical reactions that occur among 2 or more drugs inside or outside the body.

Physical Precipitate occurs when mixed. Ex. Dilantin IV and dextrose (IV solution) together form precipitate. Mix only with saline

Additive • 2 or more drugs which have same effect are combined & sum of individual effects are relative to doses used. May be harmful or beneficial. Harmful – alcohol & salicylate increase GI bleeding Beneficial – 2 pain relieving drugs (aspirin & codeine) better pain relief together than either alone.

Synergistic • 2 or more drugs, with or without same overt action used together to yield combined effect that has outcome greater than single drug alone • Harmful – chloral hydrate (hypnotic) & alcohol = prolonged CNS depression (coma/death) • Beneficial – combine groups of antibiotics for increased action (penicillin or cephalosporin with aminoglycosides), diuretic + beta-blocker decreases BP better than either alone

Potentiation • Particular type of synergistic action • Only one of two drugs exerts action greater by presence of 2 nd drug • Ex. Phenothiazide (Phenergan) + narcotic (Demerol) = increased analgesic effect of narcotic

Drug-Food Interactions • Food may decrease/increase effectiveness by binding with drugs and allow less to be absorbed or promote absorption Ex. Antibiotics (erythromycins/quinolones) bind with food, so administer 1 hr before or 2 hours after food. Tetracyclines bind with milk, cheese, antacids

Delayed Toxicity • Several days to years after exposure • Ex. – liver damage after large doses of Tylenol, exposure to Agent Orange, DES

Drug-Induced Organ Toxicities • • Skin- photosensitivity, photo allergic, phototoxic Blood dyscrasias Ocular Nephrotoxicity – BUN, creatinine Hepatotoxicity – liver function studies Ototoxicity – aminoglysides Lung toxicities – usually those with existing lung disease • Teratogenic Reactions – 1 st trimester

Chapter 6 Cultural and Psychological Aspects • Do you think there is a difference in health beliefs of you as a health care provider and the beliefs of your clients? • Review Table 6 -1 for selected groups

• What personal experiences with drug therapy might relate to your expectations of a drug’s effect on symptoms? • Pharmacogenetics? ? ? What is this? • see table 6 -2

QUIZ ---True or False 1) If you suggest to a client that a particular drug will be helpful, the drug’s effectiveness may be enhanced. 2) Many people have ambivalent feelings about taking medications.

3) Certain medications taken in usual dosages may not be effective if the client is angry or resentful. 4) An acute vs. a chronic illness may affect the client’s emotional response to a medication.

Decisions, Decisions • Under what circumstances would it be appropriate to administer a placebo? ? ? • What would you say to a client if you were about to administer a placebo and he or she asked what the medication was? ? ?

OTC Meds • A client is requesting info about medication with OTC meds. How would you respond? • What are some risks and benefits? ?

TO DO LIST • Mc. Kenry page 79–common abbreviations • Math Calculations in Math Text