Pharmacology - Drug Administration, Absorption & Distribution (Exam 1) Flashcards

1
Q

drug enters the plasma

A

absorption

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2
Q

drug transported to and from sites of action

A

distribution

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3
Q

Chemical structure of drug changed

A

biotransformation (metabolism)

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4
Q

irreversible loss of drug

A

excretion

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5
Q

loss of drug concentration or effect through distribution, biotransformation, excretion

A

elimination

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6
Q

routes for drug entry

A
  1. enteral
  2. paraenteral
  3. inhalation
  4. local
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7
Q

The delivery of any medication that is absorbed through the GI Tract

A

enteral

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8
Q

enteral routes

A
  1. oral
  2. sublingual
  3. rectal
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9
Q

occurs via injection

A

parenteral

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10
Q

parenteral routes

A
  1. intravenous
  2. intramuscular
  3. subcutaneous (under skin)
  4. intrathecal (intraspinal)
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11
Q

direct application of drug to its site of action

A

local

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12
Q

local routes

A
  1. topical
  2. intradermal (into skin)
  3. intrasynovial (into joint space)
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13
Q

what is the most common route of drug administration?

A

oral

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14
Q

general traits for oral route

A
  1. convenient and economical
  2. requires pt compliance
  3. variable absorption (generally slower)
  4. safest (can be reversed by emesis if needed)
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15
Q

When a drug is delivered orally, greater absorption occurs in the small intestine because?

A

Small intestine has a greater surface area

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16
Q

factors that affect oral drug absorption

A
  1. gastric emptying time
  2. gastric acidity/presence of food
  3. first-pass effect
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17
Q

where does the primary site for drug metabolism occur at

A

liver

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18
Q

how does first pass effect occur? (enterohepatic cycling)

A
  1. drug taken orally
  2. drug dissolved in stomach
  3. drug is emptied in the small intestine
  4. drug absorbed through portal vein to the liver
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19
Q

Some drugs cannot be given orally, and some can be given orally but at a higher dose because _____

A

it has to compensate for the 1st pass effect

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20
Q

drugs administered via Intravenous (IV) are placed

A

into the vein (not artery)

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21
Q

Absorption is ______ potentially causing immediate effects

A

circumvented

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22
Q

when is intravenous useful

A

in emergencies

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23
Q

intravenous permits

A

titration of dose
(exact amount of drug over time period)

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24
Q

intravenous is suitable for ______ or ______

A

large volumes or irritating substances if diluted

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25
Q

intravenous is not suitable for ______ or ______

A

oily solutions or insoluble substances
(can produce embolism)

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26
Q

Intravenous must be injected slowly and is also _______ and _____

A

dangerous and expensive

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27
Q

What type of drugs are required for intravenous (2

A

high molecular weight protein or peptide drugs (cannot be given orally)

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28
Q

angle in subcutaneous parenteral route

A

45 degree

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29
Q

angle in intramuscular parenteral route

A

90 degree

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30
Q

angle in intradermal parenteral route

A

10 to 15 degree

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31
Q

where is an intramuscular injection placed?

A

into the muscle (not vein)

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32
Q

Intramuscular injections can have a ______ absorption from aqueous solution or a _____ and _____ absorption from repository preparations

A

prompt absorption from aqueous solution (fast) or a slow and substained absorption from repository preparations (last longer)

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33
Q

Intramuscular injections are suitable for (2)

A
  1. moderate volumes
    -2. oily vehicles
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34
Q

intramuscular injection are _____ and can cause _______

A

painful and can cause tissue damage

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35
Q

where are subcutaneous injections placed

A

beneath the skin

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36
Q

At rest, absorption of subcutaneous injections is similar to

A

intramuscular injections

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37
Q

Subcutaneous injections are useful for _____ or _____

A

insoluble suspensions or solid pellets
(gives very long and sustained administration w/o having to reinject)

38
Q

subcutaneous injection are _____ and can cause _______

A

painful and can cause tissue damage

39
Q

vasoconstrictors can __________ when a subcutaneous injection is given

A

slow absorption

40
Q

Very rapid distribution to CNS; no drug depot (need to keep administering since rapid)

A

inhalation traits

41
Q

designed for local actions

A

Topical

42
Q

designed for systemic actions

A

transdermal (skin patch)

43
Q

List the drug movement (3)

A
  1. Drug
  2. Membrane
  3. Transport Mechanisms
44
Q

how does drugs move through a membrane

A
  1. lipid
  2. pores
  3. channels
  4. transporter and carrier proteins
45
Q

transport mechanisms for a drug (2)

A
  1. active
  2. facilitated
46
Q

filtration transport mechanism

A

moves through aqueous channels

47
Q

facilitated diffusion transport mechanism

A

carrier mediated transport w/o energy

48
Q

active transport requires

A

energy (ATP)

49
Q

what are the 2 types of active transporters

A
  1. ATP binding cassette (ABC)
  2. solute carrier (SLC)
50
Q

most common route for drug transport

A

passive diffusion

51
Q

movement of molecules in passive diffusion

A

high to low concentration

52
Q

Passive diffusion is proportional to

A
  • concentration gradient of the unionized drug (ionized cannot cross)
  • lipid-water partition coefficient
  • membrane surface area (more absorption with more SA)
  • pH gradient
53
Q

separation of water and oil in a beaker, add a drug in and some will dissolve in the oil, some in the water. The more drug placed into the liquid phase, the more lipophilic & non polar

A

lipid water partition coefficient

54
Q

Drugs are weak acid/bases & exist in ionized and non-ionized forms; the percentage of the drug that exists in an ionize and non-ionized form is related to

A

environmental pH

55
Q

Ability of a drug to cross a membrane is related to _________ but only related to non-ionized portions of the drug
(Ionized cannot cross the membrane)

A

concentration gradient

56
Q

weak acids (HA) and weak bases (BOH) ____

A

Dissociate

57
Q

what is a weak acid

A

anion + hydrogen ion

58
Q

what is a weak base

A

cation and hydroxide ion

59
Q

weak acids absorbed more at ___ pH

A

low

60
Q

weak bases absorbed more at ___ pH

A

high

61
Q

How is pH effect on drug movement measured

A

Henderson-Hasselbalch equation

62
Q

According to Le Chatelier’s Principle, adding additional reactant to a system or reducing concentration of any product will shift equilibrium to the ______

A

right

63
Q

According to Le Chatelier’s Principle, adding additional product to a system or removing reactant from system equilibrium will shift to the _______

A

left

64
Q

Another term for Le Chatelier’s principle is

A

Common Ion Effect

65
Q

weak acids under go greater absorption in an

A

acidic environment

66
Q

HA <-> H⁺ + A⁻
Increasing [H⁺] shifts equilibrium to the ________ (non-ionized form is the form that is absorbed)

A

left

67
Q

Weak bases undergo greater absorption in a relatively more _______

A

alkaline environment

68
Q

BOH <-> B⁺ + OH⁻
Increasing [OH⁻] shifts equilibrium to the ______ (non-ionized form is the form that is absorbed)

A

left

69
Q

What is the pKa of a drug?

A

The pH at which the molecule is 50% ionized and 50% unionized
pH = pKa + log(A-)/(HA)

70
Q

process by which drug absorbed in plasma gains access to sites of action

A

drug distribution

71
Q

List the factors that affect drug distribution

A
  • Blood perfusion rate
  • Membrane characteristics
  • Intracellular/extracellular pH
  • Sequestration in fat (many drugs are highly lipophyllic)
  • Protein binding (plasma and tissues)
72
Q

what happens when a drug is sequestered in fat?

A

Drug cannot be metabolized or excreted so it won’t be distributed quickly

73
Q

weak acids bind to

A

serum albumin

74
Q

weak base bind to

A

glycoprotein

75
Q

plasma protein binding is _____

A

non-specific

76
Q

Plasma protein levels change with ____ and ______

A

age and disease

77
Q

consequences of plasma protein binding

A
  • longer duration of action (less susceptible to metabolism, distribution, or excretion. Can also be a reason for toxicity due to drug displacement)
  • drug-drug interactions and displacement
  • misinterpretation of drug levels
78
Q

displacement of bilirubin by sulfonamides will causes

A

kernicterus

79
Q

drug distributions that are restricted by the blood brain barrier

A
  1. drugs with low lipid/water partition coefficients
  2. ionized drugs
  3. protein bound drugs
80
Q

how does the BBB limit drug distribution?

A
  1. tight connections limit filtration
  2. perivascular sheet of glial cells (thick sheet precludes all but highly lipophilic substances)
  3. extensive collection of membrane transporters expel drugs
81
Q

In order for drugs to cross the BBB, they must be _______

A

very lipid soluble

82
Q

increased permeability of BBB may be caused by

A

inflammation

83
Q

drugs must be ___ to cross BBB

A

lipid soluble

84
Q

many drugs under 1000 MW (not many drugs are actually this big) passively diffuse across the ________ between maternal and fetal circulation

A

placental barrier

85
Q

tissue layers between __________ and ________ become progressively thinner during gestation

A

fetal capillaries and maternal blood

86
Q

Distribution of a drug to a baby increases as ______

A

term approaches

87
Q

Apparent volume of distribution (Vd)

A

concentration in plasma = drug/volume
Co = D/Vd

  • drug binding to tissues elevates apparent volume of distribution
  • drug binding to plasma proteins depresses apparent volume of distribution
88
Q

body volume of distribution amounts

A

plasma water 3L
interstitial fluid 9L
intracellular fluid 29L
total body water 41L

89
Q

in redistribution, lipophilic drugs administered intravenously may initially distribute to…

A

vessel-rich organs (brain, heart, kidneys, liver, and lungs), and then redistribute to less highly vascularized tissues (muscle, skin, fat).

90
Q

If the site of drug action is highly vascularized then redistribution serves as a

A

drug elimination mechanism

91
Q

mechanism of drug elimination for highly lipophilic drugs

A

redistribution ex. thiopental

92
Q

describe the increased depth of anesthesia that occurs with metabolic acidosis and thiopental

A
  • thiopental is a weak acid, so nonionized form crosses the BBB
  • metabolic acidosis increases the plasma [H+], therefore [HA] increases in plasma- more [HA - nonionized form] crosses the BBB