Principles of Pharmacology

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Principles of Pharmacology
2014-05-22 22:38:47

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  1. Pharmacology
    The scientific study of the origin, nature, chemistry effects and uses of drugs

    remember it is dynamic
  2. Pharmacokinetics
    the study of the movement of drug molecules in the body

    • Absorption
    • distribution
    • metabolism
    • excretion

  3. Pharmacodynamics
    Mode of action

    • How the drug alters the cell
    • how the drug works
  4. Pharmacotheapeutics
    • The use/treatment
    • what do we use the drug for ex colace- why do u use this stool softner.
  5. Drug
    • medication
    • pharmacological agent
  6. Principles of Pharm
    1. drugs can't create a new function just Alter the cell (normal cell and function)

    • 2. drugs do multiple things and have multiple effects including side of effects
    • ex stool softner can also cause loose stools- at risk for dyhydration 

    3. drug action is an interaction between the drug molecule and the cell molecule
  7. drug development
    before it was trial and error

    came out and someone said it would work and then it killed a bunch of people

    1862- federal bereau of chemical- looked at strength and purity (not contamin

    1900- FDA standardization of drugs
  8. Five Drug Standards (FDA)
    - Purity: No contamination the drug should be what it says it is. 

    - potency- strength (how much of the drug is needed to create an effect) smallest amount of drug to produce an effect

    - bioavailabilty- how the cells use. how does it gets absorb and used in the cell. the better the bioavail the better it gets to the cell (liquid is better because it is already in the smallest size possible)

    -efficacy- effective

  9. Clinical Trials
    • discovery and identify of new drug
    • 10% of new drugs gets full aproval
  10. pre-clinical trials
    • -tested with animals
    • -making sure it does not cause cancer -carcenogenic 
    • tetragenic- birth defect
    • long term studies
    • 1/1000 drugs gets out of clincal trial

    **basic safety
  11. Clinical Trials (phrases)
    Phrases 1-3- before new drug is marketed

    Phrase 4- completed after marketing begines

    usually takes five-to nine years to complete
  12. Phrase 1
    • small sample of healthy volunteers
    • data recorded 

    less than 100 people

    basic safety (toxicity/side effects)
  13. Phrase 2
    • volunteers with the disease
    • less than 200
    • what dosage works for this problem* side effects

    what are the risk identify (most are identify in the phrase)

    nurse role- tell pt side effects, still in trial (not full FDA), what don't know all the side effects
  14. Phrase 3
    • Large number of individuals
    • 1000-3000 people

    assesses for infrequent or rare side effects

    usually uses the placebo effect (20-40%)
  15. Placebo effect
    testing to see how much of it is physiological and how much of it is psychological

    people may believe because i took this med they have improved
  16. Double Blind study
    the researcher nor the pt knows which one is the placebo and which one is the real

    the purpose behind this is so the researcher does not influence the results
  17. Cross over design study
    studying one drug that is similar to another drug
  18. First three phrases
    once all phrases are completed the manufacter can apply for a new drug application

    once it is approved it can be marketed
  19. Phrase 4
    Post marketed surveillance

    a much larger population

    closely monitor for safety

    looking for side effects that occur over time/long time

    black box warning telling us it is an increase risk
  20. Prescription Drug user free act 1992
    allowed the FDA to charge manufacturers for the FDA approval process

    usually takes 10-12 year for a drug to be approved 

    reason - gave the FDA more screeners/researcher and reduce the time of approval...
  21. Expedited Process
    if there is an urgent need for the drug the drug can go on the market before it completes all three trial.

    it has to meet a certain criteria before this gets approved

    pt must be aware that drug did not go through all three trials.
  22. Orphan Drugs
    rare/unusual disease

    drug of limited use

    rare- 1/200,000 have this disease

    no drug company wants to make

    tax benefit to companies to make this orphan drug
  23. Compassionate use protool
    streamline drug approval process

    gets drugs to pt before completed all three phrases

    • it is a lottery system
    • u have to meet a specific criteria. u have to have tried everything under the sun and nothing worked and now this is last resort. u can be in any other study. 

    life threatening diseases
  24. Pharmacokinetics- absorption
    movement of drug site of administration (where I gave it) into the blood stream

    two things that impact this rate of absorption and how much of the drug is absorbed (extent)
    • - Several variables affect the rate of drug absorption
    • - depends on the route
    • -affected by the speed in which the drug is dissolves 
    • - drugs the are administered orally takes longer to absorbed
    • - food or other drugs can interfere with aborption
  26. Other factors that may interfere withe cell
    Drugs- pill v liquid the breakdown is different related to bioavailability

    • GI mobility- acid drug likes acid enviroment
    • Physiological- ulcer, scar tissue, bowel resection, loss some intestine,fistula, mass
  27. Drug Distribution
    transports drug throughout the body

    once the drug is in blood stream how does it can transported

    process when the drug molecules leaves bloodstream and transported by body fluids to the site of action (both active and inactive)
  28. Factors that influence distribution
    • 1. blood flow and capillary permeability
    • (the rate of blood flow and vasodilation/constriction)

    2. physical property of the drug

    3. tissue abilty to store the drug (some stored in fats/bones etc)
  29. Physiologic barriers
    • Blood brain barrier 
    • placenta barrier
  30. Blood brain Barrier
    • packed cells 
    • does not allow everything to pass. it needs a transport mechanism. something to help it pass

    this is good because we don't want everything we take going to our brain.
  31. Placental Membrane
    lets everything through

    so whatever the mother has will pass to the baby. which will cause effects on the fetus
  32. Plasma Protein binding
    Drugs attach to protein- albumin

    forms a drug-protein complex (like a reseviour) 

    it floating around and it is not free and goes to the site of action when needed

    • albumin major carry
    • when the drug is free it goes to the site of action or can be excreted
  33. Plasma Protein Binding 2
    reversible process (based on bodies needs)

    malnutrition- the drug will go to the site of action or it may be excreted

    as drug levels decrease the d-p complex breaks apart and goes to the site of action
  34. Competition for protein binding sites
    two drugs can compete for the same binding site

    affinity- ability to locate 

    drug with the highest affinity will bind to protein
  35. Patients health status and disease state
    abscess formation, cardiac status, peripheral blood flow, nutritional state (malnutrition, poor protein status)
  36. Metabolism
    it is the process by which the body changes the chemical structure of a drug

    • enzymatic alteration of drug structure
    • Liver

    other site: GI tract, lungs, skin, kidneys

    biotransformation- is the outcome of the metabolic process
  37. Factors affecting the metabolic process
    • 1. disease process
    • 2. age
    • 3. genetic
    • 4. enviroment
    • 5. nutrition
    • 6. other drugs

    review on your own
  38. P450 system
    metabolic pathway

    • meds are competing for the 450 system
    •  only so many meds can be in this pathway so whatever meds has the highest affinity

    broken down into smaller pathways 

    compete for this pathway

    * drug metabolism can result in breakdown of the drug molecule or synthesis of a new drug molecule
  39. Therapeutic consequences of a drug metabolism
    - accelerated renal drug excretion- water soluble 

    - drug inactivation- 

    - enzyme induction- increase enzyme release

    - increase therapeutic action

    • - activation of a pro drug- which is when u take a drug orally it is inactive and once in body series of metabolic action makes it active
    • ex patch on and off so u don't use all the sulfahydro misp

    - increase/decrease toxicity
  40. Hepatic first pass effect
    effects oral drugs

    rapid hepatic inactivation

    take oral drug in goes into the digestive system and into the bloodstream then is transported to the portal vein to the liver where metabolism occur. it get so metabolize nothing is left. 

    increase the dosage, frequency

    * give IV, rectally, or sublingially
  41. excretion
    removal of the drug from the body

    primarily thru the kidneys
  42. Enterohepatic recycling**

    oral drugs absorbed by the intestine travel to thru the portal vein to the liver part of it may be secreted into the bile and from the bile this goes back into the intestine and into the bloodstream.

    the amount of drugs into the blood stream will be higher

    prolong the action of the drug and delay excretion

    stays in body longer
  43. Drug Clearance
    Involves the liver and kidneys

    if you have high clearance level: increases excretion rate

    already been metabolize and is excreted by the kidneys
  44. Drug Half Life (t1/2)
    The time require for the total amount of drug in the body to be diminished by half

    • metabolism and excretion determine half
    • half life does not change with the dose. 

    different drugs have different half lives. 

    it tells manufacture and pharm information about dosing and how many times u take the meds
  45. Steady State
    when the administration rate equals the the excretion rate

    keeps things stable/constant level
  46. look at example of half life
    on the mid term
  47. Drug Plasma Concentration
    • Frequency distribution curves
    • - represents the safety of a curve

    Graphic representation of the dose of the drug and the reponse

    • Target tissue- though usually not available
    • -plasma level
  48. Drug response Curve
    Profile- graphic of the drug, dose, response

    MEC- minium effective concentration- smallest amount to produce an effect (mid term)

    MTC- minium toxic concentration- this one the drug will become toxic

    Therapeutic range (safe zone)

    on mid term look at graph***
  49. Drug Response Curve (meaning)
    • Onset of action- when drug takes effect 
    • duration of the drug- how long is the drug is therapeutic
    • peak concentration- highest drug effect
    • trough level- lowest drug level- draw the labs an 1 to half hour before u give the drug. to see if the drug is effective

    loading dose- u give this to bring up to the therapeutic leve

    maintenance- maintain the therapeutic range- should be a steady state (should equal what u are excreting)
  50. Pharmcodynamics
    Mechanism of Action

    Drug action- how the drug works at the cellular

    Drug effect- what the drug is suppose to do

    drug causes a response that may lead to a therapeutic effect or an adverse effect
  51. drug Potency
    the amount of drug that elicit an effect

    produces effect at low dose
  52. Drug Efficacy
    largest response/effect achieved

    largest effect that the drug and produce

    drug potency and efficacy are independent of each other
  53. Receptor
    reactive cellular site with which a drug can interact to produce a pharmacological response

    cellular macromolecule which bind to a medication to initiate its effects

    interlocks with drug molecule (temporary)

    lock and key
  54. Receptor Theory
    when the drug binds a receptor it can mimic or block the endogenous molecule

    all receptor sites on a cell do not produce the same effects

    drug molecules are able to attach only at certain receptors
  55. Second Messenger
    • Once the drug is bound to the receptor it creates a series of response. chemical change?
    • internal actions
  56. Intrinsic activity
    abilty of the drug to activate the receptor upon binding. it creates activity within the cell (action within the cell)
  57. Affinity
    ability to locate- finds the receptor it can bind to.
  58. Other types of drug reactions
    • 1. drug enzyme interaction
    • 2. nutrient effect on a cell function
    • 3. non specific interaction- we change the permability, pH, binding sites

    make holes in the cell and the cell dies

    different ways drugs can interact with the cell
  59. receptor sensitivity
    receptors are dynamic

    sensitivity to molecules can change

    continous exposure to an agonist, the cell can become less responsive

    desensitized, refractory, down regulation- cell not as responsive

    also, hypersensitivity can occur- added effect (more)

    receptors are constantly changing
  60. Agonists
    drug molecule attaches to a receptor

    promote a function, produces the same type of response as endogenous substance

    creates a response
  61. Antagonist
    another drug molecule that prevents a response from occurring. 

    competes for the binding site

    • has affinity
    • can find cell but doesn't stimulate a response.
  62. Competitive Blockers (antagonist)
    • competes with the agonist at the receptor site
    • have the same affinity as the agonist

    • who ever has more power will win and sit in that receptor. 
    • reversible as u stop taking the drug
  63. non competitive (antagonist)
    • back door
    • it doesn't matter the concentration. it goes to a different receptor (ie back door) and stops the effect. 
    • irreversible- u have to create a new cell for the effect to comeback (neuro)

    back door theory

    it doesn;t matter how much u have of either one the blocker always wins...
  64. adverse effect
    • Undesirable effect
    • go back to meds 
    • Carcinogeric- cancer
    • teratogenic- birth defect
    • iatrogenic- mimic a disease
    • idiosyncratic- weird symptom (something that happens that is unique to u)
    • allergic
    • anaphylactic
    • toxicity
  65. drug interactions
    can occur anytime two or more drugs are administered

    can be intended or unintended

    drug interactions can affect pharmacokinetic 

    nursing role- we have to be aware of incompatiabilities IV meds can inactive each other.
  66. Additive effect
    two or more like drugs are combined and the results is the sum of the drug's effects

    ex tylenol and codeine (better control when given together than when use of either drug alone)
  67. Synergistic effect
    two or more unlike drugs are used together to produce a combined effect

    the outcome is a drug effect greater than either drug's activity alone

    ex lasix (loop diuretic) and beta blocker (lopressor)
  68. potentiated effect
    an interaction in which the effect of only one of the two drugs is increased

    enhances effect of the second drug

    ex- demerol (narcotic) and vistaril (anti emetic, antianxiety)
  69. antagonistic effect
    opposite of synergistic effect

    it is therapeutic effect that is less than the effect of either one of the drugs alone

    one drug either cancels or diminishes the other

    ex antacid and iron
  70. Drug Incompatibilities
    Chemical inactivation or a physical reaction occurs

    nursing role- if you have two different IV- you would flush the IV with 10ml of normal saline
  71. Drug incompatibilities (chemical/physical)
    Chemical incomp- chemical incomp between drugs change both the drugs structure and its pharmacoogic properties

    • Physical incomp- occur when two drugs are mixed together
    • crystalized formula changes in consistency
    • the mixture results in the formation of a percipitate (could cause emboli)
  72. look change in the older adult (on test)
    normal changes in the elder related to meds on this test p85-85
  73. drug/food interaction
    just know this occurs
  74. Nursing role
    • aviod med error
    • nurse role in med admin
    • teaching at the pt's level
    • always teach regardless of what u don't know
    • saying do u know why u are taking this meds- do u know why u need to take water with the med