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Pharmacotheraputics > Intro to Pharm > Flashcards

Intro to Pharm Flashcards

1
Q

pharmacokinetics

four parts

A

the study of what the body does to a drug

absorption, distribution, metabolism, excretion

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2
Q

absorption

A

how fast a drug is absorbed into the blood

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3
Q

distribution

A

how a drug is disseminated through out the body

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4
Q

metabolism

A

to what extent a drug is modified by enzymes in the body

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5
Q

excretion

A

how rapidly the drug is eliminated from the body usually through urine, feces

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6
Q

clinical pharmacokinetics

A

the application of PK princiles to the management of drug therapy in an individual patient

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7
Q

theraputic drug monitoring

A

using an assay to determine drug concentrations in plasma then using that concentration to develop safe and effective drug protocols

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8
Q

kinetic homogeneity

A

a predictable relationship between plasma drug concentration and concentration at the receptor site where the drug produces its pharmacologic effect

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9
Q

theraputic drug monitoring assumes what?

A

that decreasing the amount of a drug in the blood will decrease the amount at the receptor site and therefore decrease the effect of the drug

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10
Q

pharmacodynamics

A

the study of what the drug does to the body

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11
Q

what determines the pharmacodynamic effect of a drug

A

the relationship between drug concentration and at the site of action and the effect

time course and intensity of theraputic and adverse effects

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12
Q

how is the pharmacodynamic effect of a drug measured

A

physiologic (HR, RR, LOC, analgesia)

laboratory (change in cholesterol)

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13
Q

Emax

A

the concentration of a drug which will fully bind to all the available receptors and increasing dose will not increase effect

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14
Q

Emin

A

the minimum concentration below which no effect is observed

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15
Q

EC100

A

the concentration at which Emax is achieved

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16
Q

EC50

A

the concentration at which 50% concentration is achieved

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17
Q

how is potency determined

A

testing two drugs in the same patient or pool of patients and comparing their EC50 to find which requires a lower concentration

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18
Q

what determines the EC50/potency of a drug

A

affinity for receptors and the number of receptors available

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19
Q

T/F a more potent drug (lower EC50) will have a longer effect

A

false

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20
Q

drug efficacy

A

the relationship between concentration and dose that takes into account the maximum effect that a drug can have regardless of dose

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21
Q

efficacy is dependant on what

what is the assumption made when determining efficacy

A

the number of drug receptor complexes formed and the intrinsic activity of the drug

it assumes that all receptors are occupied and the drug is at Emax

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22
Q

Drug A and Drug B both occupy 100% of receptors but Drug B has less intrinsic activity

which will have a higher efficacy

A

Drug A

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23
Q

drug tolerance

A

reduced effect from repeated exposure to the same concentration of a drug

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24
Q

theraputic range

A

the concentration of a drug, typically in plasma, where efficacy is maximized and the risk of toxicity is low

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25
Q

T/F the boundaries for the theraputic range of a drug are absolulte

A

false

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26
Q

four basic criteria for theraputic drug monitoring

A

good correlation between concentration and effect

drug posses a narrow theraputic range

there is a defined theraputic range

significant interpatient variabilty in plasma concentration

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27
Q

four factors that can alter drug absorption

A

sugery, food, drugs, disease

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28
Q

four factors that can alter drug distribution

A

genetic differences in transport proteins

body composition

drugs

disease

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29
Q

three factors that can alter metabolism or elimination of a drug

A

genetic differences in the number and/or function of phase 1 and/or 2 enzymes

drugs or xenobiotics

diesese

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30
Q

eight indications for theraputic drug monitoring

A

low theraputic index

poorly defined clinical end point

non-adherence

theraputic failure

drugs with saturable metabolism

wide variation in drug metabolism

major organ failure

prevention of ADE

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31
Q

five examples of times when theraputic drug monitoring is not needed

A

clinical outcome is unrelated to dose or plasma concentration

dosage does not need to individual

the pharmacological effects can be clinically quantified

the relationship between concentration and effect remains unestablished

drugs with a wide theraputic range

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32
Q

seven classes of drugs that are common candidates for theraputic drug monitoring

A

cardiovasculars

antibacterials

anti-depressants or psychotics

antiepileptics

antifungals

antineoplastics

immunosuppresives

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33
Q

theraputic index

A

the range of doses at which a medication was effective in clinical trials for a median of participants

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34
Q

how is the theraputic index expressed

A

as the range between the median effective dose (ED50) and the median toxic dose (TD50)

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35
Q

what is the risk of putting patients on a drug regimine that is at the low end of the theraputic window

the high end

A

there won’t be an appreciable effect

they are at risk for complications

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36
Q

what constitutes a narrow theraputic window

A

if the difference between ED50 and TD50 is 2x or less

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37
Q

five drugs with narrow theraputic windows

A

warfarin

lithium

digoxin

phenytoin

zidovudine

38
Q

factors affecting absorption

A

pH

gastric emptying

blood flow

intestinal surface area

intestinal transport

transport proteins

intestinal CYP

39
Q

why does pH effect absorption

A

most drugs are weak bases

40
Q

where does most absorption happen

does pH affect this

A

in the small intestine because of large surface area and permeable membranes

41
Q

physologic factors that impact gastric emptying time

physiochemical factors

A

pH, baroreceptors

particle size

42
Q

how do dietary factors influence gastric emptying

A

changing gastric pH and the caloric load

43
Q

what is the effect of blood flow on instestinal absorption

A

more absorption happens because there is more blood flow, specifically in lipoholic drugs

44
Q

five determinants of distribution

A

chemical polarity

affinty for transport proteins

binding to tissue components or proteins

binding to blood components

volume of disstribution

45
Q

two factors that effect the chemical polarity and partitioning of a drug as it relates to distribution

A

lipophilicity (increases permability through lipid bilayers)

particle size (influences how the body handles the drug)

46
Q

metabolic elimination of a drug

A

the chemical modification of a drug to a more polar compound and facilitate clearance

47
Q

enzymes that peform metabolic elimination

A

blood esterases

phase I enzymes (oxidative, reduction, hydrolysis)

phase II (conjugative enzymes)

48
Q

sites of metabolic elimination

A

liver, GI, lungs, kidneys, skin

49
Q

excretion

A

the process by which a body ultimately eliminates a partent drug

50
Q

what are the most common routes for excretion of drugs

other routes

how are most polar drugs eliminated

A

biliary and renal

lungs, skin

through the kidneys

51
Q

how are lipophilic drugs typically exlcuded

A

they and their metabolites are eliminated through biliary, renal, or both after biotransformation

52
Q

bioavailability (f)

A

the fraction of an adminstered dose of unchanged drugs that reaches the systemic circulation that characterizes the extent of absorption

53
Q

what is the bioavailibilty (f) of IV drugs

oral

how is this determined

A

100%

1-f

determined by comparing the AUC of oral to iv administration

54
Q

factors that impact bioavailiblity

A

diet, physiology, first pass, genetics, age

55
Q

Tmax

A

time to max concentration, the time after adminstration when the maximum plasma concentration is reached

56
Q

what two values are equal at Tmax

what pharmacokinetic concept is characterized by this

A

when the rate of absorption = rate of elimination

the rate of absorption

57
Q

Cmax

what pharmacokinetic concept is characterized byt his

A

maximum concentration, the max serum concentration the drug achieves in a specific test area after the drug has been administered

extent of absorption

58
Q

Cmin

A

the minimum plasma concentration that a drug achieves in a tested area after the drug has been adminstered and prior to the adminstration of a subsequent does

59
Q

AUC (area under the curve)

what drugs will have a lower AUC

A

the area under a plasma concentration/time curve that reflect actually exposure to the drug

ones that are cleared rapidly

60
Q

half-life (T1/2Beta)

what does this assume

A

the time required for a drug to fall to 50% of its current value

that the drug is eliminated linearly

61
Q

clinical causes of increased half life (reason to reduce dose)

A

decreased blood flow to liver and kidneys

decreased renal function that lowers elimination

decreased metabolism

62
Q

clincal causes of decreased half life (reasons to increase dose)

A

increased hepatic blood flow

decreased protein binding

increased metabolism

63
Q

Ke (elimation rate constant)

A

a secondary parameter that is mathmatically derived value describing the rate at which a drug is eliminated from the body

64
Q

volume of distribtion (Vd)

equation

A

the theoretical volume that would be necessary the contain the total amount of an adminstered drug at the same concentration observed in blood plasma

Vd = (amount of drug in body)/(concentration at time zero)

65
Q

what types of drugs will tend to stay dissolved in plasma

what will be the effect on Vd? why

A

drugs witha high molecular weight and/or have a high affinity for transport proteins

it will have a high concentration in blood so Vd will be low, about 4L

66
Q

what type of drugs will stay dissolved in the extracellluar fluid

how will this effect Vd

A

drugs with low molecular weight that can pass through the capillary junctions into interstitial fluid but are too polar to cross the cell mambrane

Vd will be high, about the sum of the interstitial fluid (20% of body weight(

67
Q

what type of drugs will pass into the ICF

how will it effect Vd

A

low molecular weight and lipophilic drugs

the Vd will equal about 60% of body weight

68
Q

what type of drugs can have a Vd in excess of total body water

how is that possible

A

non-polar, unionized drugs

suggests tissue distribution

69
Q

clearnace (CL, Cl, Cl/f)

A

a measure of the volume of plasma from which drug is removed per time

70
Q

total clearance

A

the exponential effect of hepatic, biliary, and urinary elimination to decrease plasma concentration

71
Q

what determines a drugs half life

A

clearance and Vd

72
Q

linear kinetics

what is the proportion of concentration to eliminate in linear kinetics

A

first order kinetics, where a constant fraction of drug is cleared per unit of time

1:1, increase concentration increase elimination

73
Q

non linear kinetics

A

drug elimination is disproportionate to dose (2x concentration leads +/- 2x change in concentration)

74
Q

what is responsible to non-linear kinetics

A

phase I CYP enzymes

75
Q

advantages of continuous infusion

A

rate of entry is constant

results of drug accumulation until steady state is reached

76
Q

rate of IV infusion adminstration equation

A

rate of drug adminstration = steady state - rate of drug elimination

77
Q

concentration at steady state for continuous infusion is proportional to what

A

the rate of infusion

78
Q

concentration at steady is inversely proportional to what

A

clearance

79
Q

in drugs with first order elimination time required to reach concentration at steady state is dependent on what

A

half life

80
Q

what is the advantage of fixed time and dose regimens

what is the disadvantge

A

more convenient

results in fluctuating concentration

81
Q

what happens to drug concetration with muliple drug injections

A

plasam concentration increases until Css is reached

some of the drug will be eliminated

some will remain leading to accumulation

82
Q

why are most fixed dose/time drugs administered less than 5 half lives

A

so exponential elimination can’t eliminate all the drug so it will accumulate on the next dose

83
Q

disadvantages of oral administration

A

lag time to reach plasma

plasma concentration is influenced by absorption and elimination

84
Q

what is one method to reach steady state concentration faster

A

adminster a loading dose

85
Q

autoinduction

A

adminsration of a drug causes a increase in metabolism that requires an increased amount of the drug to get the same effect

86
Q

absorption is characterized by what two things

A

rate and extent (how much)

87
Q

absolute vs relative bioavailbility

A

absolute is compared to IV

relative is set to an imaginary number because there is no IV formulation

88
Q

T/F many drugs have pH dependant absorption

A

false, many are altered by pH but not many are absorbed into the blood stream

89
Q

first pass metabolism

A

when the drug is metabolized in the intestine before going into the blood

90
Q

what is the main phase I enzyme

A

cytochrome P450

91
Q

how do phase II enzymes create polor compounds

A

add a functional group

92
Q

why do we have phase I and phase II of elimination

A

because often phase one will produce a metabolite that will be processes against in phase II

Pharmacotheraputics (10 decks)

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