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Pharmacology > Lecture 4: Overview of Pharmacokinetics and Time Course of Drugs > Flashcards

Lecture 4: Overview of Pharmacokinetics and Time Course of Drugs Flashcards

1
Q

the 4 key pharmacological processes

A

absorption, distribution, metabolism & excretion

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2
Q

ADME is able to significantly impact how much drug reaches the target, which influences the ___ of the drug

A

magnitude

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3
Q

if a drug is given by the oral route, it must first be absorbed by the ___ before reaching systemic circulation

A

GI tract

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4
Q

t/f protein binding can influence how drugs move through the body

A

true some drugs are moved through the body unchanged, however, most are ___

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5
Q

ome drugs are moved through the body unchanged, however, most are ___

A

metabolized

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6
Q

what is the primary site of metabolism in the body?

A

liver

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7
Q

in the liver, drugs are converted to ____. what is the purpose of this?

A

more soluble compounds; for easier removal (excretion) from the body

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8
Q

considering pharmacokinetics processes, various __ and ___ have been developed to facilitate different therapeutic outcomes

A

routes of administration and formulations

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9
Q

many drugs are available in many formulations to allow__

A

wider use of agent

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10
Q

some drugs may have various formulations that are used for different __ and __

A

indications and purposes

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11
Q

if a drug is applied directly to the site where we want it to act, it is called ___ administration

A

local

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12
Q

when is local administration appropriate?

A

when target tissue is easily accessed

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13
Q

give 2 examples of organs that are typically receive local administration

A

skin and lungs

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14
Q

inhaled dosage forms for conditions such as asthma are unique because the drug concentration is highest in the ___, which is ideal

A

lungs

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15
Q

t/f inhaled drugs used for asthma are typically not easily absorbed through lung tissue and therefore have limited systemic effects

A

true

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16
Q

why is it ideal that asthma drugs don’t easily cross the membranes of the lungs?

A

reduces risk of off-target drug effects

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17
Q

t/f the trend of targeted drug therapy with limited systemic effects is applicable to topical treatments used for dermatologic conditions

A

true

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18
Q

the local administration route is designed to deliver drug to ___

A

where drug action is desired

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19
Q

give 2 examples of topical that are delivered locally

A

steroids and antibiotics

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20
Q

what is systemic delivery?

A

when drug is given and circulates around the body fairly extensively

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21
Q

give two routes of systemic administration

A
  1. enteral

2. parenteral

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22
Q

in enteral administration, drug is absorbed into the body through the ___

A

GI trcat

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23
Q

give 2 examples of enteral administration

A

oral and rectal

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24
Q

describe the path of Tylenol in the body

A

swallowed whole, dissolves in the stomach and absorbed in the small intestine

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25
Q

enteral administration involves the drug interacting with the ___ in some way before entering systemic circulation

A

GI tract

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26
Q

what is the most common enteral route?

A

oral

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27
Q

what makes the parenteral administration different from the enteral route?

A

skips the GI tract

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28
Q

in parenteral administration, drugs are delivered directly to the __

A

systemic circuit

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29
Q

give examples parenteral routes (7)

A

IV, SC, IM, epidural, transdermal, inhaled, intranasally

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30
Q

what is the most straight forward, fastest parenteral route? why?

A

IV; skips multiple steps / barriers, delivering straight to systemic circuit

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31
Q

give an example of drug that can be absorbed by inhalation and delivered systemically

A

nicotine

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32
Q

give an example of drug that can be delivered transdermally for systemic effects

A

nicotine patch

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33
Q

the drug formulation of a nicotine patch allows for what sort of drug delivery?

A

slow release to systemic circuit via skin

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34
Q

drugs must cross ___ to gain access to the systemic circuit

A

membranes

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35
Q

give 2 examples of exceptions to the “must cross membrane to reach target” rule

A
  1. Iv because directly systemic

2. local application bc already delivered to action site

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36
Q

what is the blood brain barrier?

A

extra barrier to limit of substances to the CNS

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37
Q

what membrane must be crossed in oral administration?

A

GI mucousal lining

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38
Q

what membrane must be crossed in transdermal administration?

A

skin

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39
Q

what membrane must be crossed in inhaled administration?

A

lung epithelium

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40
Q

in most cases, ___ is the first necessary step after administration

A

absorption

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41
Q

if you are designing a drug to target the CNS, what is an extra consideration?

A

it will also need to cross the blood brain barrier

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42
Q

lipophilic drugs can easily cross _____ membranes

A

epithelial

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43
Q

highly lipophilic drugs are no water soluble, therefore may ___ and end up not __

A

aggregate ; absorbing

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44
Q

hydrophilic drugs cross membranes by ____ or ___

A

passive difusión or transporters

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45
Q

t/f ionized molecules are not likely to cross the membrane passively

A

true

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46
Q

many drugs are weak __ /___

A

acids / bases

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47
Q

extent of ionization of weak acids/bases is determined by ___ of the compartment

A

pH

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48
Q

the __ properties are often the most important determinant of whether an agent will reach systemic circulation and its target

A

chemical

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49
Q

the __ changes along the length of the GI tract

A

intraluminal pH

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50
Q

t/f compounds that may be ionized in the stomach pH may be neural in the small intestine

A

true

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51
Q

what 2 components of the small intestine makes it the primary site of absorption?

A
  1. large surface area

2. neutral pH

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52
Q

what is a risk of the low pH of the stomach?

A

many drugs can be destroyed

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53
Q

once absorbed in the GI tract, drugs travel via the ___ before reaching the systemic circuit

A

hepatic portal vein

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54
Q

hepatic enzymes ___ drugs

A

metabolize

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55
Q

t/f only a fraction of orally administered drug reaches systemic circulation, reducing the bioavailability of the drug

A

true

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56
Q

the fraction of orally administered drug that reaches the systemic circuit is a property of the drug formulation called __

A

bioavailability

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57
Q

list 6 factors that reduce bioavailability

A
  1. first-pass metabolism
  2. metabolism by epithelial enzymes
  3. poor absorption of drug
  4. breakdown of drug in stomach
  5. P-glycoprotein pumps remove drugs from cells
  6. sequestration of drug in bile or tissue @ site of administration
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58
Q

drugs that inhaled are at risk of being metabolized by __

A

enzymes of the lung epithelial cells

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59
Q

bioavailability Is defined as

A

the fraction of administered drug reaching the systemic circuit

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60
Q

once the drug is absorbed into the blood, what is the next step?

A

distribution

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61
Q

what is distribution?

A

movement of drug from the blood to the tissues & extracellular spaces

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62
Q

what is a common tissue where drugs are distributed to?

A

adipose tissue

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63
Q

the extent of tissue distribution determines how much drug is available to ___

A

act on its target

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64
Q

define volume of distribution (Vd)

A

theoretical value used to describe the tissue distribution of drugs

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65
Q

what are 2 issues with drugs that preferentially distribute to accumulate in tissues like adipose?

A
  1. leads drug away from target

2. storage of drug in this region can have long-term effects as drug diffuses back to circulation

66
Q

the volume of distribution is calculated as the ratio of ___ over __

A

total amount of drug in body (mg) over blood concentration of drug (mg/L)

67
Q

the “apparent” volume of distribution gives an indication as to ___

A

whether the drug distributes extensively into the tissues

68
Q

why is the volume of distribution commonly called the “apparent” volume of distribution?

A

Vd does not correspond to real volume of body fluid

69
Q

the Vd can be experimentally determined by characterizing the ___ phase of a ___ graph

A

early distribution; drug concentration /time

70
Q

can Vd of a drug change based on alterations in other pharmacokinetic properties?

A

no

71
Q

can changes of body composition affect Vd?

A

yes

72
Q

drugs that can distribute through total body water have a Vd of ~__L

A

42

73
Q

give an example of a compound that can distribute through total body water and its Vd

A

ethanol, 40L

74
Q

drugs that accumulate in the tissues typically have a Vd of ___

A

much greater than 42L

75
Q

give an example of. drug that accumulates in the tissues and its Vd

A

propranolol, 400L

76
Q

drugs that are restricted to the plasma volume have a Vd of __

A

much less than 42

77
Q

give an example of a drug restricted to plasma volume and its Vd

A

biologics, 3L

78
Q

the utility of apparent Vd is that we can predict___

A

where a drug may be going in the body

79
Q

a 70Kg adult male has about ___L of total body fluid

A

42

80
Q

___L is used as a benchmark to compare the distribution of drugs in different compartments of the body

A

42

81
Q

drugs that bind excessively to plasma proteins have Vds of ___

A

much less than 42

82
Q

give an example of a plasma protein that drugs often bind to

A

albumin

83
Q

give an example of a drug that binds extensively to plasma proteins

A

warfarin

84
Q

explain why the Vd is so low when drug is extensively bound to plasma proteins

A

its trapped in the vascular space, unable to freely distribute

85
Q

t/f protein binding is freely reversible

A

true

86
Q

if a patient is stable on a Warfarin dose, adding another medication may result in ___

A

displacement of warfarin from the plasma protein, resulting in more free drug, which can lead to adverse effects as warfarin is a very potent drug

87
Q

some drugs may ____ distribute to specific tissues

A

preferentially

88
Q

biphosphonates preferentially distribute to ___ through ___ interactions

A

bone marrow through ionic interaction

89
Q

99% of total body fluoride is found in the ___ and ___

A

bones and teeth

90
Q

fluorine integrates into the ___ of bones and teeth

A

enamel matrix

91
Q

Amiodarone is an antiarrhythmic drug that contains a ___group that is unrelated to its activity, but because os it, accumulation in the ___ may cause adverse effects

A

iodine; thyroid

92
Q

biphosphates and fluorine preferentially bind what mineral?

A

calcium

93
Q

amiodarone is selectively taken up by the thyroid gland for the biosynthesis of ___

A

thyroid hormones

94
Q

what are the characteristic of drugs that are filtered out of the blood into the urine?

A

small, polar, water-soluble

95
Q

t/f small, polar, water-soluble drugs may be detected in urine sample “unchanged”

A

true

96
Q

many drugs need to be ___ for effective excretion

A

modified

97
Q

metabolism tends to make compounds more __

A

polar

98
Q

the processes of drug excretion from the body are defined as drug ___

A

clearance

99
Q

t/f depending on the properties of the drug, clearance may have several components and contributions from different organs

A

true

100
Q

elimination is another term used to describe the process of removing drugs from the systemic circulation, where clearance is described as a ___ for a particular drug and elimination is described as the ___

A

constant parameter; rate of drug removal

101
Q

for the most part, drugs in this course follow ___order kinetics where elimination is dependent on ___

A

first; concentration

102
Q

what is the primary means to remove drug>?

A

urine

103
Q

the process of the kidneys filtering drugs for excretion is called

A

renal excretion

104
Q

t/f most drugs need to be modified in order to be more easily excreted

A

true

105
Q

create/unmask polar functional groups by oxidation, hydrolysis, reduction are all characteristic of what phase of metabolism?

A

phase 1

106
Q

conjugation, adding polar groups by glucoronidation or methylation are all characteristics of what phase of metabolism?

A

phase 2

107
Q

biotransformation occurs most often in the ___ and uses a variety of ____ recations to make drugs more polar

A

liver; biotransformation

108
Q

t/f drugs can undergo Phase 1 or Phase 2 metabolism, or both and not necessarily in order

A

true

109
Q

what type of drug needs to be activated by biotransformation(metabolism?

A

pro-drugs

110
Q

give an example of a pro-drug and the active form once biotransformed in the body

A

codeine; morphine

111
Q

t/f the metabolites of a metabolite may also have activity, so it is important to consider all the active forms

A

true

112
Q

phase 1 metabolism is largely carried out by the __ enzymes

A

cytochrome P450

113
Q

phase 1 metabolism also involves CYP metabolism by isoenzymes such as ___, ___, ___ and ___

A

3A4, 2C9, 2C19, 2D6

114
Q

what are the 2 key enzymes in phase 2 metabolism and what are they each responsible for?

A
  1. glucuronosyl transferases : create glucuronide conjugates
  2. glutathione transferases : make glutathione conjugates
115
Q

other enzymes such as __ and ___ have important metabolic roles in the actions of drugs

A

oxidases and hydrogenases

116
Q

what are neprhronns?

A

individual filtering units in the kidneys

117
Q

nephrons use ___ and ___ to remove substance from the blood

A

passive discussion and transporters

118
Q

give an example of a compound that is reabsorbed into the blood in the nephron

A

glucose

119
Q

rate of renal excretion is determined by ____ and ___

A

glomerular filtration rate and drug concentration

120
Q

t/f drugs bound to proteins are more easily filtered

A

false

121
Q

what is renal excretion>

A

the passive or active transport of molecules from the blood to the urine

122
Q

while renal excretion is the primary site of elimination, drugs can also be lost by __, ___, ___, and ___

A

bile, sweat, feces, expiration

123
Q

___ is used to model the plasma concentrations of drugs and design their dosing regimen

A

quantitative pharmacokinetics

124
Q

what are the 5 key parameters of quantitative pharmacokinetics?

A
  1. half life (t 1/2)
  2. Vd
  3. clearance Cl
  4. steady-state concentration (Css)
  5. bioavailability (F)
125
Q

what is the half life?

A

time required for the concentration of the drug to drop by 50%

126
Q

in first order kinetics, the proportion of drug ___ remains constant

A

cleared

127
Q

with a single dose IV, the ___ increases rapidly, but begins to drop as the drug is __ and __

A

blood concentration; metabolized and excreted

128
Q

what are the risks of administering a single dose IV?

A

in the beginning the dose can be in the toxic range and can quickly drop below therapeutic levels

129
Q

administration by continuous IV prevents peaks and valleys in drug concentration by matching ____ to achieve steady state concentration within therapeutic range

A

drug clearance rate

130
Q

the key to achieving steady state level is matching ___ to __

A

amount of drug in to amount of drug out

131
Q

the drug ___ and ___ determine the steady state concentration that is achieved

A

dose administered and the half life

132
Q

in single dose IV duration of effect is determined by __ and ___

A

therapeutic range and half life

133
Q

in continuous IV, the ____ rate is determined to achieve equal drug in to drug out

A

infusion

134
Q

____ dosing is the most common at-home dosing regimen

A

repeated oral

135
Q

repeated oral dosing can achieve similar steady state blood concentrations to that of ___

A

continuous IV

136
Q

oral dosing is delayed compared to IV due to __

A

time to be absorbed by intestine

137
Q

duration of effect for oral dosing depends on __ and __

A

therapeutic range and half life

138
Q

general rule of thumb is that steady state concentration isn’t achieved until after ___ half lives of the drug

A

5

139
Q

if the dose is too high, or the interval is too short, drug blood levels may be __

A

toxic

140
Q

if the dose is too low or the interval is too long , the drug blood levels may be ___

A

too low have an effect

141
Q

____ doses “fill up” the volume of distribution

A

loading

142
Q

a loading dose followed by ____ will get the blood concentrations into the therapeutic range faster

A

multiple maintenance

143
Q

t/f even with a loading dose, it will still take about 5 half lives to reach steady state

A

true

144
Q

define drug interaction

A

change in pharmacologic effect of a drug that results when given concurrently with another drug or food

145
Q

the most known drug interactions are related to altered ___

A

pharmacokinetic parameters (ADME)

146
Q

non-pharmacokinetic drug interactions include ___ and ___ type interactions

A

chemical incompatibility and pharmacodynamic

147
Q

provide 2 causes of modulation of CYP enzymes

A
  1. drug / other compounds such as toxins, chemicals, and natural products
  2. altered expression of CYP, change in lifespan, or antagonism of binding sites
148
Q

most drug interactions have been found to occur due to changes in drug ___

A

metabolism

149
Q

drugs can influence the ___ capacity of CYP by acting as either ___ or ___

A

metabolic, inducers or inhibitors

150
Q

what are the effects of CYP inducers?

A

increase metabolism resulting in faster excretion and lower blood concentration

151
Q

CYP inducers can result in what adverse effects?

A

treatment failure and reoccurrence of symptoms

152
Q

what are the effects CYP inhibitors?

A

prevent drug metabolism

153
Q

what are the adverse effects of CYP inhibitors?

A

may cause drug to accumulate at toxic levels

154
Q

give 2 examples of CYP inducers

A

St. John’s wort, and phenobarbital

155
Q

give 2 examples of CYP inhibitors

A

ketoconazole and grapefruit juice

156
Q

pharmacodynamic drug interactions occur when the ___ of different drugs interact

A

pharmacologic effects

157
Q

t/f the synergistic effect of using multiple antihypertensives can be beneficial

A

true

158
Q

t/f the combined effect of increasing NT levels with two different anti-depressants can be dangerous

A

true

159
Q

using drug with opposite effects at the same receptor can result in ___ or ___

A

inadequate therapeutic response or worsening symptoms

160
Q

chemical incompatibilities result when two drugs interact making one or both ___

A

inactive

161
Q

give an example of two drugs with chemical incompatibilities

A

penicillin and amino glycoside antibiotics

Pharmacology (49 decks)

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