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INTRODUCTION TO PHARMACOLOGY > pharmacodynamics > Flashcards

pharmacodynamics Flashcards

1
Q

definition of pharmacodynamics

A

is the study of the mechanism of action of a specific drug

it is the relationship between drug concentration and responses that occur in the body due to the drug

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2
Q

why be concerned about how drug work?

A

knowledge of how a drug works increases the nurse’s confidence and it ensures that the drug is being used appropriately to prevent medication error.

improves the ability to educate, assess and evaluate patients

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3
Q

definition of mechanism of action

A

means the way a drug produces a therapeutic effect. once the drug hits its site of action it can modify the way a cell of tissue functions . mechanism of action of most drugs involve the interaction of the drugs with receptors or enzymes.

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4
Q

what is a drug-receptor

A

it is a specialised macromolecule to which a specific group of drugs or naturally occuring substances can bind

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5
Q

once the substance binds to and interacts with the receptor, a __________ is produced

A

pharmacologic response / therapeutic effect

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6
Q

what is the receptor theory?

A

it is when a drug molecule binds to a reactive site on the cell which is the receptor. once the substance binds to and interacts with the receptor a pharmacologic response/therapeutic effect is produced

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7
Q

_____+__________= drug affect

A

drug and receptor

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8
Q

what are the structures of receptors

A

most receptors are proteins found on the plasma membrane of a cell or tissue

some receptors are intracellular molecules such as DNA or enzymes in the cytoplasm

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9
Q

what is the function of receptors?

A

is to bind endogenous molecules

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10
Q

what are some examples of endogenous molecules?

A

hormones and neurotransmitters

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11
Q

when a drug binds to a receptor is can be classified as either :

A

agonist or antagonist

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12
Q

what is agonist?

A

agonist mimics the effect of the endogenous substance that normally binds to the receptor and produces the response

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13
Q

examples of agonist

A

epinephrine (adrenaline) neurotransmitter

the epinephrine neurotransmitter, at the adrenergic synapses, is an agonist. it is produced by the adrenals, it binds to the receptor and there is a response for our fight and flight

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14
Q

what is the antagonist?

A

drug occupies the receptor and prevents the endogenous substance from binding.

The drug binds to receptor prevents binding of agonist.

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15
Q

example of antagonist

A

alpha and beta adrenergic blockers

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16
Q

blockage of myocardial beta 1 receptors may

A

decrease force and rate of. contraction

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17
Q

what is affinity

A

affinity is the degree to which a drug binds with a receptor

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18
Q

the drug with the best ________ or _______ will elicit the best response

A

best fit or affinity

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19
Q

what are enzymes

A

enzymes are substances that catalyze nearly every biochemical reaction in a cell

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20
Q

drugs can interact with enzyme systems to

A

alter a response

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21
Q

Enzyme inhibitors _______ action of enzymes

A

inhibits

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22
Q

what is the function of enzyme inhibitors

A

it inhibits action of enzymes. the enzyme is fooled into binding to a drug instead of a target cell. it protects target cell from enzyme’s action.

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23
Q

what do ACE ( angiotensin-converting enzyme inhibitors) inhibitors do?

A

it reduced blood pressure

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24
Q

how does an enzyme system work?

A

1) substrate enters the active site of the enzyme
2) enzyme-substrate complex forms
3) substrate is converted to products
4) products leave the active site of the enzyme

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25
Q

what are non-specific interactions?

A

some drugs bypass the enzyme system. MOA of some drugs is that they do not go to a receptor site or alter an enzyme function.
main site of action is cell membrane or cellular process. these drugs will physically interfere or chemically alter cell process. final product is altered causing defect or cell death.

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26
Q

where is the main site of action of non-specific interaction drugs?

A

cell membrane

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27
Q

examples of non-specific interaction drugs

A

cancer drugs, antibiotics

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28
Q

what is a therapeutic index

A

it is the measure of the safety of a drug

it is the ratio between a drug’s therapeutic benefits and its toxic effects.

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29
Q

therapeutic index formula

A

median lethal dose LD50/ median effective dose ED50

30
Q

what is a median lethal dose (LD50)

A

the amount of drug that will be lethal in 50% of a group of animals

31
Q

what is a median effective dose (ED50)?

A

the amount of a drug required to produce a response in 50% of the subjects to whom the drug is given

32
Q

low therapeutic index =

A

not good because it means the safety margin is small

33
Q

what is the relationship between the therapeutic index and safety of a drug

A

the higher the TI, the safer the medication

34
Q

larger the TI, the _____ the drug

A

safer

35
Q

must be > ___ for the drug to be usable

A

1

36
Q

when a drug is given to a single patient, the intensity of the response can be seen in a ____________

A

drug-response curve

37
Q

how many phases in drug-response curve?

A

3

38
Q

what happens during phase 1

A

occurs at lowest dose . few target cells affected by drug

39
Q

what happens during phase 2

A

linear relationship. linear relationship between amount of drug administered and degree of client response. i.e doubling the dose doubles the drug response

40
Q

which phase is the most desirable

A

phase 2

41
Q

what happens during phase 3

A

increasing dose has no therapeutic effect

the increased dose may produce adverse effects

42
Q

what is potency

A

refers to the measure of how much a drug is required in order to produce a particular effect.

43
Q

what is efficacy

A

refers to the magnitude of the maximal response that can be produced by the drugs

44
Q

drug interaction may occur with either

A

with either drugs or food

45
Q

what are drug-drug interactions

A

changes in a drug’s effect caused by the presence of another drug taken during the same period

46
Q

type of drugs which are at risk of drug interaction

A
  • narrow TI (low safety drug)
  • steep dose-response curves
  • drugs where a loss of effect may lead to disease breakthrough
47
Q

why do drugs with steep dose-response curves at risk of drug interaction

A

a minor change in plasma concentration may take a major change in effect example warfarin

48
Q

patients who are at risk of drug interaction

A
  • elderly, polypharmcy, poor homeostatic mechanism
  • severely ill patients
  • patients who depend on prophylactic therapy for disease suppression
49
Q

those who are at risk of drug interaction

A

patient with renal of liver disease

patient with more than one physician

50
Q

types of drug-drug interactions

A

duplication
opposition (antagonism)
alteration

51
Q

describe and explain what happens during duplication

A

duplication may occur when a person inadvertently takes two drugs, that have the same active ingredient.

when two drugs with the same effect are taken, their therapeutic effects and their side effects may be intensified.

52
Q

what is opposition

A

when two drugs with opposing actions interact, reducing the effectiveness of one or both

53
Q

what is alterations

A

one drug may alter how the body absorb, distributes, metabolizes, or excretes another drug

54
Q

what are drug-food interactions

A

changes in a drug’s effects caused by food consumed in the same period of time

55
Q

presence of food in the digestive tract may _____________ of a drug

A

reduce absorption

56
Q

what happens when warfarin interact with foods rich in vitamin k such as broccoli, spinach

A

reduce the effectiveness of anticoagulants (warfarin) increasing the risk of clotting. intake of such foods should be limited and the amount consumed daily should remain constant

57
Q

what happens when tetracycline interact with calcium foods

A

these foods can reduce the absorption of tetracycline, which should be taken 1 hour before or 2 hours after eating

58
Q

what happens when statins interact with grapefruit

A

grapefruit contains substance that affects the intestinal absorption of drugs such as statins

59
Q

what is drug-medicinal herb interactions

A

drugs interact with certain medicinal herb or supplement taken by patients at the same time

60
Q

what is an adverse drug reaction

A

is an adverse outcome of drug therapy in which a patient is harmed in some way

61
Q

causes of ADR

A

pharmacologic reactions

hypersensitivity reactions

idiosyncratic reactions

62
Q

Pharmacologic reactions are ________, ______ -related, , occurs due to _________

A

predictable, dose, action of drug

63
Q

hypersensitivity reactions are _______-related , requires _____________, _______ develop when drug acts as antigen or allergen , ______________ produces hypersensitiy reaction

A

not dose, prior exposure, allergies, subsequent exposure

64
Q

idiosyncratic reactions are ___________, ______-realted or allergic, occurs in __________ percentage of people

A

unexpected, not dose-related, small

65
Q

ADRS is also known as

A

side effects

66
Q

if a drug is teratogenic

A

it causes fetal malformation

67
Q

if a drug is mutagenic

A

it causes mutations of DNA

68
Q

if a drug is carcinogenic

A

it causes cancer

69
Q

if a drug causes tolerance

A

there is a decreasing response when repeated doses are given

70
Q

if a drug causes dependence

A

patients have a physiologic or psychological need to a drug

INTRODUCTION TO PHARMACOLOGY (5 decks)

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