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165 Cards in this Set
- Front
- Back
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Pharmacology is the science that drawson information from multiple disciplines, including:
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Anatomy, Physicology, Psycology, Chemistry and Microbiology
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Pharmacology is
**Question |
The study of the effects of drugs and their interaction with living systems
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Clincial Pharmacology is
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the study of drugs in humans
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Therapeutics is
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the use of drugs to diagnose, cure, treat or prevent disease
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What is a drug?
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a drug is any chemical that can affect living processes
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3 Reasons to study Pharm
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1. To safely administer meds
2. To educate others 3. Manage a therapeutic drug regimen |
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Properties of an Ideal Drug (3)
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Efectiveness, safety, and selectivity
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Is there a perfect drug?
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No.
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Effectiveness
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elicits the responses for which it is given. The most important property a drug can have
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Safety
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a drug that cannot produce harmful effects (there is no such thing as a safe drug)
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Additional Properties of an Ideal Drug
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Reversible Action
Predictability Easy of administration Freedom from drug interactions Low Cost Chemical Stability Simple generic name |
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BBB
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Blood Brain Barrier
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Characteristics of an Ideal Drug (8)
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1. Effectively treats, prevents or cures
2. Produces a rapid, predictable response at low doses 3. Produces no adverse effects 4. Can be taken conveniently by mouth 5. Taken once a day 6. Inexpensive and easily accessible 7. Quickly eliminateed from the body 8. Does not interact with other drugs or food |
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Therapeutic Objective
**Question |
The objective of drug therapy is to provide maximum benefit with minimum harm
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Factors that determine the intensity of drug responses (4)
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1. Administration
2. Pharmacokinetics 3. Pharmacodynamics 4. Sources of individual variation (p450) everyone metavolizes differently, weight, age etc |
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Administration variations
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medication errors
patient adherence |
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Pharmacokinetics variations
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absorption
distribution metabolism (liver) excretion (kidneys) |
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Pharmacodynamics variations
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drug-receptor interaction
patient's functional state placebe effects |
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Individual variations
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physiologic variables
pathologic variables genetic variables drug interactions |
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6 rights
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1. Right Medication
2. Right client 3. Right dosage 4. Right route 5. Right time 6. Right documentation |
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What two lab tests ordered to test kidney function?
**Question |
Blood Uria Nitrogen (BUN)
and Creatinin Levels |
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What if BUN and Creatinin are high?
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lower dose and increase invertal of time b/t doses
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Aspirin
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pain, antiplatelette, fever, antiinflammatory
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Collecting baseline data is important because
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then you can compare it to other states to evaluate therapeutic responses and adverse effects
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Identifying high-risk patients
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Liver and Kidney impairment
Genetic Factors Drug allergies Pregnancy Elderly and peds Tools are pt history, physical exam, and lab results |
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extravasates
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IV leaking to tissue rather than bloodstream
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Analysis and Nursing Diagnosis objectives (3)
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1. Judge the appropriateness of the prescribed regimen
2. Identify potential health problems that the drug might cause 3. Determine the patient's capacity for self-care |
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Drug Therapy Problems (7)
**Question |
1. Unnecessary drug therapy
2. Need for additional drug therapy 3. Ineffective drug 4. Dosage too low 5. Adverse drug reaction 6. Dosage too high 7. Noncomplicence |
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Beta Blockers
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vasodilators
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Rennin from kidneys
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secrete angiotensin I which creates angiotensin II plus ACE inhibitors = vasodilate
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Important US DRUG LEGISLATION
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esspecially FDA in 1988
but look up all on slide!!! |
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Orphan drugs
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drugs that have limited use (treat rare or unusual diseases) usually less than 200,000
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Compassionate Use
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certain drugs are avaliable to partients without complete FDA approval---life theatening diseases
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Expeditied Process
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shorten process for diseases that may produce a public health threat (AIDS Swine)
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Randomized Controlled Trails (3)
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Use of controls
Randomization Blinding |
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Stages of New Drug Development
**Question |
1. Preclinical testing
2. Clinical testing (may take 2-10 years) 3. Human studies |
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Human Studies (4 Phases)
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Phase I: Initial pharmacologic evaluation-- lab research
Phase II: Limited controlled evaluation-- clinical trials with healthy individuals Phase III: Extended clinical evaluation -- drug approval process (NDA) with people who have the pathology Phase IV: Post marketing surveillance -- survey for harmful drug effects in larger population |
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Pregnancy Staefy Categories for Drugs
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Category A: no risk to fetus in first trimester
Category B: no risks in animals, no good human studies Category C: animal adverse effects, but no good human studies. benefits outweigh the risks Category D: evidence of fetal risk but potential benefits may be acceptable despite risk if no safer drugs Category X: fetal abnormalities and risk. these drugs should not be used in pregnant women |
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Nuremberg Code for Human Rights in Research (6)
**Question |
1. Voluntary
2. Human need to be necessary 3. Risks are justified 4. Unnecessary suffering is avoided 5. Carefully and professionally conducted 6. Sugject or investigator can stop at any time |
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Cranial nerve I type
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Sensory
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Basic principles of Pharmacology (5)
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1. Pharmacokinetics
2. Pharmacodynamics 3. Drug interactions 4. Adverse drug reactions and medication errors 5. Individual variation in drug responses |
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Pharmacokinetics
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the study of drug movement or motion throughout the body-- how drugs enter the body, reach their site of action and are removed from the body
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Example of Pharmacokinetic route
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oral drug>stomach>portal vein>liver>systematic circulation>target tissue>target cell
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Both pharmacokinetics and pharmacodynamics of a drug
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determine how a drug is administered, how often it is given, and at what dosage
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Basic Pharmacokinetic Processes (4)
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Absorption
Distribution Metabolism Excretion |
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Phases of Drug Activity (3)
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Pharmaceutical Phase
Pharmacokinetic Phase Pharmacodynamic Phase |
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Passage of Drugs across membranes
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1. Channels and pores
2. Transport systems 3. Direct penetration of the membrane |
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Absorption
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Process involving the movement of the drug from its site of administration into the blood
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Bioavailability
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describes what proportion of the administered drug is available to produce systemic effects
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First Pass
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drugs that are absorbed from the small intestine and transported to portal circulation for metabolism. The liver may biotransform much of the drug before it can enter general circulation
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Rate of absorption
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determines how soon the effects will begin
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Amount of absorption
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determines how intense effects will be
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Factors that affect drug absorption
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rate of dissolution
surface area blood flow lipid solubility pH partitioning |
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Commonly uses routes of administration
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Intravenous
Intramuscular Subcutaneous Oral Topical Transdermal Inhaled Suppositories |
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Persistence
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drugs that persist in the body are bound to proteins (albumin) rather than being dissolved directly in the plasma
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Drugs that bind to plasma proteins
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often have a long duration of action
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Distribution
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the movement of drugs throughout the body-- transport of a drug in body fluids from the bloodstream to body tissues and to the site of action
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Distribution examples
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capillary beds
blood brain barrier placenta; drug transfer protein binding entering cells high lipid solubility and low protein binding favor diffusion of the drug through membranes high concentration of free drug in the blood also favors diffusion into tissues |
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Drug distribution is determined by (3)
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1. Blood flow to tissues
2. Exiting the vascular system 3. Entering cells |
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Blood brain barrier
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Tight junctions between the cells that compose the walls of most capillaries in the CNS
Drugs must be able to pass through cells of the capillary wall only drugs that are lipid soluble or have a transport system can cross the BBB to a significant degree |
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Placental Drug Transfer
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Membranes of the placenta do NOT constitute an absolute barrier to the passage of drugs--movement is determined in the same way as other membranes
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Risks with drug transfer across the placenta
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birth defects, mental retardation, gross malformations, low birth weight
a mother's use of opioids give birth to a drug dependent baby |
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Protein binding
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drugs can form reversible bonds with various proteins
plasma albumin is the most abundant and important |
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Metabolism (biotransformation)
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Enzymatic alteration of drug structure
the ability of living organisms to modify the chemical structure of compounds the liver is the most important site for biotransformation |
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P 450 system
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drugs are metabolized in the liver using the system which helps in the biotransformation of lipids soluble drugs
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Therapeutic consequences of drug metabolism
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acceleration of renal excretion of drugs
drug inactivation increased therapeutic action activation of prodrugs increases toxicity decreased toxicity |
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Special considerations in drug metabolism
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Age
Induction of drug metabolizing enzymes First pass effect Nutritional status Competition between drugs |
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Excretion
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Defined as the removal of drugs from the body
the kidneys account for the majority of drug excretion Nonrenal routes of excretion-- breast milk, bile, feces, lungs, sweat, saliva |
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Renal routes of drug excretion
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Steps in renal drug excretion:
--glomerular filtration --passive tubular reabsorption --active tubular secretion |
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Factors that modify renal drug excretion
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--pH dependent ionization
--competition for active tubular transport --age |
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Glomerular filtration
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filtration moves drugs from blood to urine
protein bound drugs are not filtered |
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Passive reabsorption
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lipid soluble drugs move back into the blood
polar and ionized drugs remain in the urine |
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Active transport
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tubular pumps for organic acids and bases move drugs from blood to urine
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Time course of drug responses
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plasma drug levels
single dose time course drug half life drug levels produced with repeated doses |
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Plasma drug level: minimum effective concentration
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defined as he plasma drug level below which therapeutic effects will occur
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Plasma drug level: toxic concentrations
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when the plasma drug level climbs too high
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Plasma drug level: therapeutic range
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enough drug present to produce therapeutic responses-- the objective of drug dosing is to maintain plasma drug levels within the therapeutic range
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Therapeutic Index
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measure of a drug's safety
the ratio of the drugs LD50 (average lethal dose to 50% of animals tested) the larger/higher the therapeutic index, the safer the drug the smaller/lower the therapeutic index, the less safe the drug |
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Therapeutic range objective
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dosage is used to maintain plasma drug levels within the therapeutic range
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single dose time course
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the duration of effects is determined largely by the combination of metabolism and excretion
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Half Live (t1/2) of a drug
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most common description of drug's duration
the time is take for blood level to fall to one half of the level measured at some prior time tells how fast it disappears form bloodstream due to metabolism and excretion Is affected by rates of metabolism and excretion determines the dosing interval****** |
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Plateau Principle
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When you give the same dose of the same drug by the same route, at the same time interval and nothing else changes it takes 4-5 half-lives from the start of drug administration for blood levels to reach a plateau
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Steady State
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the point at which the amount of drug being administered and the amount being eliminated balance off-- plateau will have been reached
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Drug levels produced with repeated doses
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reduces fluctuations in levels
plateau will be reached in approx 4 half lives and when the drug is eliminated, it will be gone in about 4 half lives as well |
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The intensity of a drugs effect is related to the amount of...
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free (unbound) drug in the bloodstream
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a Loading Dose
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is administered to reach a therapeutic response level rapidly.
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a Maintenance dose
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is administered at prescribed intervals to maintain a therapeutic drug response
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Pharmacodynamics
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study of the biochemical and physiologic effects of drugs and the molecular mechanisms by which those effects are produced
The study of what drugs do to the body and how they do it |
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Knowing the pharmacodynamics helps a nurse to
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educate patients
make PRN decisions evaluate patients for drug responses collaborating with physicians about drug therapy |
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Pharmacodynamics Examples
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Dose-response relationships
Drug-receptor interactions Drug responses that do not involve receptors Interpatient variability in drug responses The therapeutic index |
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Dose Response Relationships
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relationship between the size of an administered dose and the intensity of the response produced
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Dose response Relationships determines
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the minimum amount of drug we can use
the maximum response a drug can elicit how much we need to increase the dosage to produce the desired increase in response |
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Dose Response Relationships
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as the dosage increases, the response becomes progressively larger
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Maximal Efficacy
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the largest effect that a drug can produce.
the nurse should match the intensity of the response with the patient's need |
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Potent drug
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a potent drug is one that produces its effects at a low dose
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Plasma levels of a drug
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trough and peak
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Neurotoxicity
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harm a nerve cell or nerve tissue
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Hepatotoxicity
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damage to the liver
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Nephrotoxicity
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damage to the kidneys
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Ototoxicity
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damage to the 8th CN
(hearing balance and awareness of the body) |
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Cardiotoxicity
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irregularities in cardiac rhythms and conduction, heart failure, damage to the myocardium
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Immunotoxicity
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effect the immune system
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Receptors are...
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specific proteins in the body intended to respond to some chemical normally present in blood or tissues
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Specificity is...
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the property of the receptor that lets it discriminate and bind only to those with critical features
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Receptors make a selective drug action possible...
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the more selective a drug is, the fewer side effects it has
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Binding of a drug to its receptor is usually...
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reversible
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Receptor activity is regulated by
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endogenous compounds
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When a drug binds to a receptor...
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it will either mimic or block the action of the endogenous regulatory molecules and increase or decrease the rate of physiologic activity normally controlled by that receptor.
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affinity
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strength of the attraction between the drug and its receptor
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Efficacy
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the capability of stimulating the receptor to pharmacological resonse
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agonist--
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a drug that combines with receptors and produces a biologic effect by stimulating the receptor-- has both affinity and efficacy--molecules that activate
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antagonist--
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drugs that counteracts the action of other drugs at he receptor-- prevents stimulation/activation of receptors
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partial agonist--
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drug binds to receptor and there is diminished response compared with that elicited by the agonist
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Competitive antagonist
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drug competes with the agonish for bining to receptor. if it binds, there is no response
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Noncompetitive antagonist
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Drug combines with different parts of receptor and inactivates it so agonist has no effect
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Drug interactions
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any modification of the action of one drug with another drug
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antagonism
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when one drug interferes with the action of another
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additivity
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when two drugs seem to act completely independently of each other, and their combined effect is what would be expected adding the effects of two drugs alone
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synergy
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occurs when the effect of two drugs combined is greater than the additive effect
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Consequences of Drug-Drug interactions
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-intensification of effects
-reduction of effects -creation of a unique response |
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Ways to minimize Adverse Drug-Drug reactions
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minimize number of drugs a patient receives
take a thorough drug history de aware of the possibility of illicit drug use adjust the dosage when metabolizing inducers are added or deleted adjust the timing of administration to minimize interference with absorption monitor for early signs of toxicity be especially vigilant when patient is taking a drug with low therapeutic index |
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Adverse Drug Reactions
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any noxious un intended and undesired effect that occurs at normal drug doses
can range from annoying to life threatening |
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ADRs are most common in...
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the elderly and very young
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Side effect
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a nearly unavoidable secondary drug effect produced at therapeutic doses
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Toxicity
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adverse drug reaction caused by excessive dosing
--may occur even with normal dosing |
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Allergic reaction
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Immune response determined primarily by the degree of sensitization of the immune system--not by drug dosage
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Very few drugs cause severe allergic reactions
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penicillins are the most common
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Idiosyncratc effect
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an uncommon drug response resulting from a genetic disposition
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Iatrogenic disease
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a disease produced by drugs
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Physical dependence
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develops during long term use of certain drugs
a state in which the body had adapted to drug exposure |
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Teratogenic Effect
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a drug induced birth defect
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Drugs that you suspect of causing a previously unknown adverse effect should be reported to
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MedWatch-- the FDA Medical products Reporting Program
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Liver toxicity signs
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jaundice, monitor LFT
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Kidney toxicity signs
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urinalysis and serum creatinine (by creatinin clearance)
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Bone marrow toxicity signs
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periodic blood cell counts
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Medication errors are the major cause of
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morbidity and mortality
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Six rights
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1. Right Medication
2. Right client 3. Right dosage 4. Right route 5. Right time 6. Right documentation |
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Individual variation in drug responses
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Body weight and composition
Age-- infants (organ immaturity) elderly (organ degeneration, due to illness multiple pathologies or multiple drugs) Kidney, liver, acid base imbalance, altered electrolyte status |
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Tolerance
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decreased responsiveness to a drug as a result of repeated drug administration (therefore, require higher doses)
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Pharmacodynamic tolerance
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associated with long term administration of drugs such as morphine
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Metabolic tolerance
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resulting from accelerated drug metabolism
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Tachyphylaxis
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reduction in drug responsiveness brought on by repeated dosing over a short time
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Bioavailability
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ability of the drug to reach the systemic circulation from its site of administration
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Other causes of variable absorption
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gastric pH, diarrhea, constipation, food in the stomach
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Pharmacogenomics
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study of how genes affect individual drug responses
--altered drug metabolism --altered drug targets |
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Variations of genetics
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gender, race, failure to take medicine as prescribed (manual dexterity, visual acuity, intellectual capacity, psychological state, attitude toward drugs and ability to pay for medication) Drug interactions, diet.
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Changes in pregnancy that influence pharmacokinetics
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total body water, increased aldosterone levels, increased 5% of body fat and weight, dilutional decrease in serum albumin levels, progesterone stimulates hepatic enzyme system, increase in cardiac output, increase in renal blood flow
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Placenta is
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a temporary organ that allows for nutrition and gas exchange between the mother and fetus
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approximately 10%
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of the mother's cardiac output circulates through the placenta
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Factors that impact drug transfer
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Plasma drug level in the mother
solubility of the drug molecular size protein binding blood flow to the placenta |
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majority of drugs are secreted into breast milk BUT
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very few need to be discontinued
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Avoid drugs with long half lives while breast feeding and SR formulations
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be careful
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Due to organ immaturity
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very young patients are highly sensitive to drugs
elevated drug levels and delayed elimination |
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Neonates and infants do not have a well developed
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BBB
and their metabolism is faster and excretion slower |
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dosage of drugs is most commonly based on
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body surface area
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elderly (65+) consume 30% of drugs
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woah.
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goals of therapy
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maintain the health status using the fewest drugs possible
start slow, go slow |
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Absorption: elderly
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rate of absorption may slow
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Distribution: elderly
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increased percentage of body fat
decreased percentage of lean body mass decreased total body water Reduced concentration of serum albumin (significant in the malnourished) |
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Metabolism: elderly
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hepatic metabolism declines with age
reduced hepatic blood flow, reduced liver mass, and decreased activity of some hepatic enzymes occur half life may increase and responses are prolonged |
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Excretion: elderly
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renal function undergoes progressive decline (reductions in renal blood flow, GFR, active tubular secretion and number of nephrons)
**most important cause of adverse drug reactions |
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Use creatinine clearance to test
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kidney function
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pharmacodynamics: elderly
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alterations in receptor properties may underlie altered sensitivity to come drugs
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Predisposing ADR factors...
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Drug accumulation secondary to reduced renal function
polypharmacy greater severity of illness multiple pathologies greater use of drugs that have a low therapeutic index increase individual variation secondary to altered pharmacokinetics inadequate supervision of long term therapy poor patient adherence |
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75% of nonadherence is...
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intentional!! expense, side effects, patient's conviction that the drug is unnecessary or the dosage is too high
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