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FMS > FMS Week 4 > Flashcards

FMS Week 4 Flashcards

Pharmacology

1
Q

albumin

A

plasma protein binding agent for mostly neutral/acidic drugs

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2
Q

Significance of gefitinib and EGFR mutations

A

only 10% of patients respond to gefitinib due to somatic mutations around the ATP-binding pocket of the EGFR tyrosine kinase domain

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3
Q

DR = ([Rt][D]/(Kd + [D]))

A

Version of Michaelis-Menten that relates drug receptor binding to affinity, total number of receptors, and body concentration

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4
Q

what physiochemical properties of drugs affect distribution out of the plasma?

A

lipid solubility (partition coefficient) and pKa of the drug

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5
Q

β2AR polymorphisms and albuterol response

A

Homozygotes for Arg-16 in β2AR gene are 5.3x (and heterozygotes 2.3x) more likely to respond to albuterol

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6
Q

what is an example of a covalent bonding drug?

A

aspirin

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7
Q

what is the therapeutic window of a drug?

A

the range of concentrations between the minimum therapeutic concentration and the toxic concentration

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8
Q

what factors affect clearance of a drug?

A

greater volume of distribution and higher elimination constants increase clearance

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9
Q

TPMT

A

enzyme associated with thiopurine inactivation, overactive in over-metabolizers leading to decreased active (cytotoxic) products

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10
Q

structural changes of hydroxylation

A

RCH2CH3 to RCH2CH2OH

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11
Q

t{1/2} = 0.693(Vd)/CL

A

formula for the half-life of a drug based on the clearance (which is a function of the elimination constant)

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12
Q

what is the latency of a drug?

A

the time from administration to therapeutic concentration

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13
Q

what are spare receptor agonists?

A

when maximal response is achieved without using all of the receptors (intrinsic activity greater than 1)

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14
Q

what factors affect GI absorption?

A

surface area, GI pH, GI motility/gastric emptying, blood flow

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15
Q

how much non-interstitial, extracellular water is there in the body?

A

3L in a 70kg man (20% of extracellular water) in the plasma

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16
Q

what is the duration of a drug?

A

the time that blood concentrations stay in the therapeutic window

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17
Q

how would you calculate the desired dose of a medication?

A

Dose= Volume of distribution X therapeutic concentration

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18
Q

what form of bases can pass through lipid membranes?

A

unprotonated weak bases

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19
Q

most common phase II mechanism?

A

glucuronidation

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20
Q

what is the intrinsic activity of an antagonist?

A

zero

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21
Q

t{1/2} = 0.693/k

A

Formula for the half-life of a drug based on the elimination constant

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22
Q

define volume of distribution

A

the volume of fluid needed to contain the administered amount of drug at the concentration measured in blood or plasma (V=amount administered/concentration measured)

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23
Q

what factors decrease the rate of passive diffusion?

A

thickness of the membrane, concentration on “inner” side of the membrane

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24
Q

inhibitors of CYP

A

cimetidine, erythromycin, ketoconazole, chloramphenicol, acute alcohol, grapefruit juice

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25
Q

what is true of the drug concentration [D] in first-order drug metabolism?

A

It is small; less than the metabolism constant (Km)

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26
Q

D = D{0}^e-kt

A

Rate equation for the AMOUNT of drug present in the body at a given time after administration

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27
Q

how do drugs permeate across placental barrier?

A

the placenta is highly permeable via simple diffusion

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28
Q

what type of transport is involved with endogenous compounds?

A

facilitated diffusion

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29
Q

how would the plasma concentration and half-life of a drug compare for an undermetabolizer vs a hypermetabolizer?

A

the plasma concentration would be higher and the half-life would be longer for an undermetabolizer

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30
Q

what are the 2 key microsomal enzymes?

A

NADPH-cytochrome p450 reductase and cytochrome P450

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31
Q

define pharmacokinetics

A

actions of the body on drugs

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32
Q

what are the types of microsomal metabolism induction?

A

phenobarbital-like (more enzyme) and Polycyclic hydrocarbon-like (decreasing metabolism)

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33
Q

What is ED50?

A

the dose at which 50% of the population reaches the desired effect

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34
Q

what form of acids can pass through lipid membranes?

A

protonated weak acids

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35
Q

what is the quantitative definition of affinity?

A

the concentration of drug (Kd) at which ONE-HALF of total receptors are bound by the drug; molar qty, (lower value = greater affinity)

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36
Q

margin of safety

A

the 1% toxic dose/ 99% effective dose

less than 1 would be less safe, greater than 1 would be more safe

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37
Q

TI = TD50/ED50

A

Formula relating therapeutic index to the 50% toxic and effective doses

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38
Q

C = (Q/kVd) * (1- e^kt)

A

formula for concentration of a drug in the body following infusion for an amount of time

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39
Q

what is the role of intestinal enzymes in free drug action?

A

glucuronides may be hydrolyzed by intestinal or bacterial β-glucuronidase to be reabsorbed

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40
Q

how does blood/urine acidity affect excretion?

A

acidic urine (relative to blood) will take in basic drugs for excretion and relatively basic urine will take on acidic drugs

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41
Q

what is true of the of the drug concentration [D] in zero-order drug metabolism?

A

it is relatively high; often unpredictable

42
Q

how do drugs permeate across the blood-brain barrier?

A

primarily through ATP-driven drug efflux pumps on the luminal plasma membrane

43
Q

what mechanisms contribute to extrarenal clearance?

A

hepatic metabolism and biliary excretion

44
Q

characteristics of plasma protein binding

A

reversible, nonselective, & competetive

45
Q

how much body water belongs to erythrocytes?

A

3L (about 10% of intracellular water)

46
Q

what are the cardiovascular factors of drug distribution?

A

cardiac output and regional blood flow

47
Q

globulins

A

plasma protein binding agent for basic drugs

48
Q

MD = LD - (LD)e^-kt

A

Formula for calculating the maintenance dose needed based on the size of the loading dose and time since administration

49
Q

inducers of CYP

A

phenobarbital, phenytoin, polycyclic hydrocarbons, chronic alcohol, St. John’s wort

50
Q

what is the ratio of extracellular water to intracellular water in the body?

A

1:2 (14L to 28L in a 70kg man)

51
Q

what are the characteristics of carrier-mediated transport?

A

can occur against concentration gradient, has competitive inhibition for similar substrates

52
Q

formula for loading dose for a given route of administration?

A

loading dose=
(V(d) * C)/F

F=bioavailability

53
Q

structural changes of sulfoxide formation

A

R1SR2 to RSOR2

54
Q

what is the intrinsic activity of an agonist?

A

greater than zero

55
Q

what is an antagonist?

A

has no intrinsic activity itself, but interferes with the binding of a ligand (endogenous or agonist)

56
Q

describe the biotransformation effects of the liver

A

products have generally lower biological activity, and are more polar (facilitating excretion)

57
Q

Difference between desensitization and down-regulation

A

Desensitization is rapid, the result of receptor phosporylation, and results in decreased affinity

Down-regulation is slower, is the result of receptor turnover, and results in decreased receptor numbers

58
Q

list the routes of drug administration

A

PO, IV, IM, SC, rectal, inhalation, sublingual, intrathecal, transdermal

59
Q

Re = γ([Rt][D])/{Kd + [D])

A

version of michaelis-menten that relates receptor response to intrinsic activity, receptor concentration, body concentration, and affinity

60
Q

what factors affect affinity of a ligand to its receptor?

A

number of interacting sites, types of forces involved

61
Q

structural changes of desulfuration

A

R1CSR2 to R1COR2

62
Q

how much body water does a normal 70kg man have?

A

42L (60% of body weight)

63
Q

G6PD deficiency results in what? by what mechanism?

A

hemolysis, inability to process oxidative stressors

64
Q

where does first-pass metabolism occur?

A

the liver, and to a lesser extent the intestinal epithelium

65
Q

what is the difference between noncompetetive antagonists and inverse agonists?

A

Noncompetetive antagonists bind to ligand-dependent receptors away from the ligand binding site to inhibit

Inverse agonists bind to ligand-independent receptors to inhibit their constitutive activity

66
Q

what classes of drugs are metabolized by CYP2D6?

A

antidepressants, antiarrhythmics, beta blockers, and analgesics

67
Q

ATP-binding cassette (ABC)

A

3 families (B,C, &G) of P-gp transporters involved in carrier-mediated transport

68
Q

components of Glucuronidation

A

Phase II metabolism; microsomal enzyme UDP glucuronosyl transferase and donor uridine 5’-disphosphate (UDP) glucoronic acid

69
Q

rasburicase

A

drug that leads to increased peroxides from uric acid breakdown, which causes hemolysis in people with G6DP deficiency

70
Q

what types of drugs are associated with facilitated diffusion?

A

analogs of endogenous compounds

71
Q

what is an agonist?

A

a drug that mimics the effects of the endogenous ligand for a receptor (has intrinsic activity)

72
Q

what is the significance of fat reservoirs on drugs?

A

may affect onset and duration of action

73
Q

what types of permeation is associated with lipid-soluble drugs?

A

passive diffusion

74
Q

what is the relationship between renal function and plasma half-life of a drug?

A

plasma half-life increases exponentially with decreasing renal function

75
Q

what factors increase the rate of passive diffusion?

A

area of the membrane, concentration on “outer” side of the membrane

76
Q

what factors determine bioavailability of a drug?

A

Physiological (first pass metabolism, blood flow), Physiochemical (drug solubility), Biopharmaceutical (tablet dissolution, particle size)

77
Q

V = Vmax[D]/(Km+[D])

A

Michaelis-Menten equation for determining the RATE of drug concentration at a given body concentration

78
Q

MD = (CL * Css)/F

A

Formula for calculating the maintenance dose needed based on clearance, steady-state concentration, and bioavailability

79
Q

how much of the extracellular water in the body is interstitial?

A

about 80% (11L in a 70kg man)

80
Q

what is the usefulness of partial agonists?

A

tend to be safer (does not elicit maximal response even at maximum receptor binding); intrinsic activity is less than 1

81
Q

what disease factors might affect drug metabolism?

A

chronic liver disease (hepatitis, cirrhosis, cancer), decreased hepatic blood flow (cardiac dysfunction), pulmonary/thyroid disease

82
Q

C = C{0}^e-kt

A

Rate equation for determining CONCENTRATION of a drug at a given time after administration

83
Q

define the effect of partition coefficient on absorbtion

A

greater partition coefficient indicates faster absorbtion (function of lipid solubility)

84
Q

structural changes of deamination

A

RC(NH2)HCH3 to RCOCH3 +NH3

85
Q

what types of drugs are associated with endocytosis/exocytosis?

A

a few very large or impermeant substances

86
Q

typically how long does it take for plasma concentration to plateau after first dose?

A

about 4 half lives

87
Q

what are thiopurines used for?

A

autoimmune conditions, leukemias, and organ transplant rejection prevention

88
Q

define pharmacodynamics

A

actions of drugs on the body

89
Q

what is the role of P-glycoproteins?

A

they oppose absorption of certain molecules. Found in GI tract, liver, kidney, blood/barrier etc.

90
Q

what is typically true of the rate of metabolism (V) in first-order drug metabolism?

A

it is generally less than 10% of the Vmax, and it is directly proportional to the concentration [D]

91
Q

TPMT

A

Enzyme that leads to inactive metabolites of thiopurines

92
Q

enterohepatic cycling

A

water-soluble drugs are eliminated in feces (via bile), lipid-soluble drugs are reabsorbed

93
Q

what is true of the rate of drug metabolism (V) in zero-order drug metabolism?

A

V= Vmax; the rate cannot go any faster

94
Q

structural changes of dealkylation

A

RNHCH3 to CNH2O

95
Q

rank the types of bonding from strongest to weakest

A

Covalent, Ionic, Hydrogen, Hydrophobic, Van der Walls

96
Q

what receptor is associated with codeine?

A

mu-opioid receptor

97
Q

Define bioavailability

A

fraction of unchanged drug that reaches systemic circulation (AUC of administration route/ AUC of IV)

98
Q

how are glucuronides eliminated?

A

in the bile

99
Q

Describe tamoxifen metabolism

A

Prodrug for endoxifen, metabolized by CYP2D6, higher metabolism leads to better disease-free survival in breast cancer

100
Q

what type of drugs are associated with passive diffusion through aqueous filled pores?

A

very small molecules

101
Q

G6PD deficiency?

A

assoated with haemolytic anaemia due to decreased antioxidant capacity (less than 60% enzyme activity), somewhat x-linked recessive expressivity (many genetic variants)

102
Q

what are the 4 pharmacokinetic processes?

A

ADME; absorption, distribution, metabolism, elimination

FMS (10 decks)

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