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Baby Pharm > Week 3 > Flashcards

Week 3 Flashcards

1
Q

T/F
One compartment model is used when drugs are handled at different rates in the tissue and plasma.

A

False
Two or more compartment models: seen when drug moves into tissues and is handled at different rates than central plasma compartment.

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2
Q

T/F
ADME is considered pharmacodynamics.

A

False
ADME is part of the pharmacokinetics lecture.

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3
Q

Most drug molecules cross tissue membranes by

A

simple lipid diffusion

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3
Q

blood-to-gas partition coefficient

A

partial pressure of the gas or volatile agent in the blood divided by the partial pressure of the gas or volatile agent in the gas at the alveoli (PA) once equilibrium has been reached.

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4
Q

T/F
tissue-to-blood partition coefficient can be used to determine effect

A

False
Some drugs may only enter a tissue to a small extent compared with other agents but may still produce greater effects.

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4
Q

T/F
Partial pressures of the
gases and volatile agents is equal to concentrations of nongaseous molecules.

A

False
Partial pressures of the
gases and volatile agents is similar (although not exactly
the same) to concentrations of nongaseous molecules.

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4
Q

pH where an acid or base
exists 50% in the ionized form and 50% in the un-ionized
form is known as

A

pKa, or –log (Ka)

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5
Q

acid dissociation constant

A

Ka

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6
Q

Lidocaine is a (weak/strong) (acid/base). With a pKa of….

A

weak base; 7.9

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7
Q

Which has a higher pKa? Procaine or Lidocaine?

A

Procaine 8.9

Lidocaine 7.9

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8
Q

Absorption

A

drug moves across membrane into bloodstream

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9
Q

Fick’s Law

A
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10
Q

T/F
Warfarin is highly protein bound.

A

True
warfarin is approximately 99% bound to plasma proteins

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11
Q

What percent of the cardiac output does the brain receive?

A

15%
allows a large percentage of
the anesthetic molecules in the plasma to be presented to
the brain for absorption

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12
Q

Biotransformation

A

is metabolism!

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13
Q

T/F
All administration methods require drug molecules to cross cellular membranes to gain access to the central compartment and
then be transported throughout the body.

A

False
IV and arterial admin do not require this

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14
Q

(One-compartment model)
Once equilibrium is reached, the drug [ ] at the site of action is…..

A

approximately the
same as in the plasma.

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15
Q

A plasma sample shows a drug [ ] equal to the drug [ ] at the site of action. This follows the ____ compartment model.

A

one

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16
Q

One-compartment model

A

-entire body is viewed as one compartment
-the drug is freely and evenly distributes to all tissues

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17
Q

T/F: when drugs are given intravenously, every molecule reaches the systemic circulation

A

True

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18
Q

what kind of model are anesthesia drugs characterized by?

A

two compartment models bc anesthetic drugs distribute extensively into peripheral tissues

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19
Q

Rate at any time is proportional to

A

the concentration of the drug

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20
Q

elimination is always out of the

A

central compartment

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21
Q

what phases are involved in the two compartment model?

A

distributive and elimination

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22
Q

what is bioavailability?

A

% of a drug or drug product that enters the general systemic circulation

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23
Q

IV administration has no _____ phase.

A

absorptive

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24
Q

T/F
IV drugs are eliminated faster than PO.

A

False

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25
Q

2 ways elimination can occur

A

metabolism
excretion

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26
Q

Elimination of drugs is usually a ____ order rate process.

A

First

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27
Q

Which rate of kinetics is dependent on the concentration of the drug?

A

First-order rate kinetics
as drug [ ] decreases, elimination rate decreases

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28
Q

Elimination of a drug following ____ kinetics is a logarithmic rate.

A

first-order

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29
Q

Which rate-order kinetics occur when metabolism of excretion processes become saturated?

A

Zero

saturation = zero order

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30
Q

In zero order kinetics, the drug [ ] (is/isn’t) related to the amount being eliminated.

A

is not

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31
Q

T/F
In zero-order kinetics, we can change the drug [ ] to increase elimination.

A

False
altering the drug [ ] does not change how many molecules can be eliminated per unit time

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32
Q

Linear elimination is seen in ____ order kinetics.

A

Zero

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33
Q

Which order kinetics shows a constant amount/number of drug molecules being eliminated per unit time?

A

Zero

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34
Q

Before reaching saturation (zero order kinetics) most drugs get eliminated by….

A

first order kinetics

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35
Q

If elimination rate of the same drug differs with each patient, how do we determine the average elimination rate?

A

Drugs that have a fairly consistent elimination rate among individuals can be used to find an average

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36
Q

The one compartment model

A

entire body = single compartment
drug evenly & freely distributes to all tissues

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37
Q

in which compartment model does the plasma drug [ ] = tissue drug [ ]

A

one

38
Q

T/F
Drug molecules must cross cellular membranes in order to gain access to the central compartment and be transported throughout the body.

A

False
IV and intra-arterial do not have to do this

39
Q

Ka
(capital K, subscript lowercase a)

A

rate of absorption (drug moves from admin site to central compartment)

40
Q

What happens in the one-compartment model once equilibrium is reached?

A

Drug [ ] at site of action is approximately the same as in the plasma

41
Q

T/F
Depending on how the drug was administered, elimination may not be necessary.

A

False
All drugs must be eliminated

42
Q

Drugs well characterized by the one-compartment model are often…

A

small molecules
highly water-soluble
distribute following total body water

43
Q

The only rate processes demonstrated by IV injection are …

A

distribution and elimination

44
Q

In the two compartment model, drugs (do/do not) demonstrate similar concentrations between the central compartment and the site of drug action at ____.

A

do not
steady state

45
Q

K12

A

rate of the drug moving into the tissue compartment from the central compartment

46
Q

K21

A

rate of back movement from the tissue to the central compartment

47
Q

T/F
a two-compartment model can be used to approximate three or four compartment models.

A

True

48
Q

rates of drug movement for compartment models are determined…

A

experimentally from serial plasma samples

49
Q

When dose the elimination process begin?

A

as soon as the first drug molecule enters the central compartment

50
Q

What is present during all phases of the plasma concentration curve?

A

elimination (Ke)

51
Q

What is responsible for the steady decrease in plasma [ ] once a drug is fully absorbed & steady state is achieved between the central and tissue compartments?

A

It is entirely due to elimination

52
Q

t1/2

A

elimination half-life

53
Q

In order to use this equation, the drug must…

A

follow first-order elimination

note the ln
first-order shows logarithmic decline

54
Q

What does the 2 represent?
What does the ln represent?

A

“2” refers to the change in the concentration by a factor of two (one-half )

ln is the natural log required due to the logarithmic nature of first-order elimination kinetics

55
Q

simplified elimination half-life equation

A
56
Q

Can we rely on the manufacturer’s elimination half-life data?

A

not entirely

wide range of half-lives due to patient variability

(ie: hepatic or renal Dz)

57
Q

Drug interactions can alter half-life by…

A

-induce liver metabolic enzymes (e.g., phenobarbital, rifampin, carbamazepine)

-inhibit the metabolic enzymes (e.g., cimetidine, ciprofloxacin, isoniazid)

58
Q

drugs that induce liver metabolic enzymes

A

phenobarbital
rifampin
carbamazepine

59
Q

drugs that inhibit the metabolic enzymes

A

cimetidine
ciprofloxacin
isoniazid

60
Q

half-life of effect

A

accounts for possible active metabolites that may prolong duration

provide a more accurate handle of the half- life of the expected effects, not just of the parent drug

61
Q

Which measurement better predicts how long a drug’s effects will last?
-elimination half-life
-half life of effect

A

-half life of effect

accounts for active metabolites

62
Q

T/F
Metabolism of Diazepam produces metabolites with the same effect as the original drug.

A

True

63
Q

Vd

A

volume distribution

volume of plasma in which the drug is dissolved

tells us whether the drug:
-stays in the plasma
-follows total body water
-concentrates in body tissues

64
Q

T/F
Volume of distribution is an concrete measurement.

A

False
it is a theoretical/apparent volume

65
Q

T/F
Heparin easily travels into tissue.

A

False
stays in the plasma compartment

66
Q

When does the volume of distribution directly related to the plasma volume?

A

if the drug stays in the plasma (ie: heparin)

67
Q

If the Vd is very large, what does this tell us about the drug? Why does this happen?

A

it leaves the plasma compartment & concentrates in tissue

only small amount of drug remains in the plasma –> low concentration –> apparent volume of distribution to appear very large

68
Q

The Vd of propanolol tells us…

A

it can reach 100’s of L

it leaves the plasma compartment & concentrates in tissue

69
Q

How much time is needed for initial drug mixing in the plasma compartment?

A

5 min

70
Q

How would we calculate Cp0?

A

impossible to sample plasma at time zero as drug needs to mix

  1. serial plasma sample curve of drug [ ] vs. time
  2. start at ~ 5 minutes to allow mixing
  3. back-extrapolate to time 0 to obtain the value
71
Q

Vd can be obtained from the ___ of a drug.

A

clearance

72
Q

clearance
vs.
plasma clearance (Cl)

A

clearance: rate by which a drug is removed

plasma clearance (Cl): volume of plasma that is entirely cleared of the drug per unit time

73
Q

T/F
Clearance is represented by (Cl)

A

False
Cl is PLASMA clearance

clearance: rate by which a drug is removed

plasma clearance (Cl): volume of plasma that is entirely cleared of the drug per unit time

74
Q

clearance is expressed in…

A

units of volume/time

75
Q

If 50% of a drug was removed from hepatic plasma, this means that….

A

half of its plasma is now 100% cleared of drug

clearance measures the volume of plasma cleared of the drug, now how much of the drug itself

76
Q

T/F
The sites of desired action and undesired action are different.

A

False
they may or may not be the same

77
Q

Side effects and toxicity are (pharmacokinetic/pharmacodynamic) principles.

A

pharmacodynamic

shows how drug affects body

78
Q

side effects vs. toxicities

A

differ in severity of undesired effects

tolerable = side effects

intolerable/life-threatening = toxicities

79
Q

only drug concentration readily accessible in the body

A

plasma [ ]

80
Q

T/F
Tissue effects are based directly on tissue concentration.

A

False
not all drugs follow this

81
Q

T/F
We can use Lithium plasma levels to determine if a patient is receiving proper dosing.

A

True
Lithium has a well-defined therapeutic window; strong relationships between plasma [ ] and therapeutic & toxic [ ]’s

82
Q

(In drugs where plasma [ ] correlates with its effects) what is the goal when dosing?

A

keep plasma drug concentration
ABOVE the minimum therapeutic concentration (Cpther)
BELOW the plasma concentration associated with toxicity (Cptox)

83
Q

(large/small) therapeutic index (TI) drugs are safer

A

Large
ie: diazepam (TI>100)
vs Digoxin (TI~2)

84
Q

Changing the infusion rate only alters ___ as long as the drug concentration stays within ___ order kinetics

A

maintained plasma [ ]
first order

85
Q

Goal of IV infusion/steady state

A

give drug at the same rate it is being eliminated

86
Q

as the plasma concentration increases, a larger amount of the drug is removed per unit time

A

first order elimination

87
Q

Without a loading dose, how long could it take to reach 95% of the steady state plasma [ ] via IV infusion?

A

5 half lives

88
Q

What is the purpose of a loading dose?

A

to reach steady state plasma concentration more rapidly

89
Q

T/F
If you give a proper loading dose before starting an infusion, no other loading dose is needed.

A

True
When IV infusion is preceded with a properly calculated loading dose, the desired steady-
state plasma concentration will be reached immediately & maintained for as long as the IV infusion is continued

90
Q

T/F
If a new plasma steady state is desired, changing the infusion rate is enough to achieve it quickly.

A

False
it will again take approximately five drug half-lives to reach the new steady state

91
Q

Intermittent dosing requires reasonably long half-life, usually…

A

6+ hours
to be given every 12 or 24 hours

92
Q

Therapeutic window in intermittent dosing

A

must be wide enough that the plasma [ ] does not fall below minimum therap. [ ] during the period between doses

93
Q

Most common form of intermittent dosing

A

PO

94
Q

Steady state in IV infusion vs. intermittent dosing

A

Both: need loading dose or we wait 5 1/2 lives to reach 95% of steady-state plasma levels

intermittent: no single steady-state concentration is reached; peaks and troughs in plasma [ ] curve

95
Q

average steady state

A

average between peak and trough concentrations
(intermittent dosing especially)

96
Q

In intermittent dosing, what happens if we do not change the dose or dosing interval?

A

the peaks and troughs
in the plasma concentration curve will occur at equal plasma concentrations

Baby Pharm (4 decks)

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