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Pharmacology > ADME > Flashcards

ADME Flashcards

1
Q

 A:
 D:
 M:
 E:

A

 Absorption
 Distribution
 Metabolism
 Excretion

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2
Q

 Absorption

A

How a drug moves from its site of
administration into the bloodstream

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3
Q

 Distribution

A

Movement of the drug between blood and
tissues

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4
Q

 Metabolism

A

Conversion of drugs into more hydrophilic
metabolites

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5
Q

 Excretion

A

Removal of drugs and/or metabolites from
the body

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6
Q

Features that predict
movement
(4)

A

 Molecular size
 Degree of ionization
 Lipid solubility
 Protein binding

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7
Q

Rule 1
 To pass through lipid membranes, drugs
have to be
 To be water soluble, drugs need to be

A

non-ionized (aka: uncharged)
ionized (aka: charged)

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8
Q

**Most drugs are either

A

weak acids or weak bases**

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9
Q

Weak acid
Occurs more in a — environment

A

basic

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10
Q

Weak base
Occurs more in a — environment

A

acidic

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11
Q

Remember: Acids are non-ionized (fat soluble)
when —, ionized (water soluble) when
—

A

protonated, deprotonated

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12
Q

Bases are non-ionized when —,
ionized when —

A

deprotonated, protonated

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13
Q

The pKa is the pH at which

A

there are
equal amounts of protonated and
nonprotonated

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14
Q

 pH = pKa
 pH < pKa
 pH > pKa

A

Protonated equals non-
protonated
Protonated form predominates
Non-protonated form predominates

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15
Q

Only the — of a drug can
readily cross the lipid membrane

A

non-ionized form

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16
Q

Ratio of ionized and non-ionized
influences rate of —

A

absorption

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17
Q

Henderson-Hasselbalch equation

A

pH = pKa + log [Ionized]/[Non-ionized]

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18
Q

Ion Trapping

A

 Because ionized
molecules (drugs)
can’t cross the
membrane, can
effectively trap them
and enhance
excretion
 Principle is very
useful in toxicology

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19
Q

Acidic environments of abscesses will affect ionization state of

A

local anesthetics

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20
Q

Acidic environments of abscesses will affect ionization state of local anesthetics
(3)

A

 Local anesthetics = basic, high pKA
 Abscess = low(er) pH
 When a basic drug is in an acidic pH, the protonated and ionized form predominates

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21
Q

Absorption
(3)

A

 Movement of a drug from its site of administration into the central compartment
 Process of dissolution and diffusion
 Bioavailability more important

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22
Q

Bioavailability (F)
(3)

A

 Fraction of drug that reaches the systemic
circulation intact
 Bioavailability of IV = 100%
 Affected by route of administration

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23
Q

First Pass and Hepatic Extraction
(2)

A

 Hepatic extraction ratio
 First pass clearance

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24
Q

 Hepatic extraction ratio

A

 Fraction of drug in blood that is irreversibly
removed during one pass through the liver

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25
Q

 First pass clearance

A

 Extent to which a drug is removed by the liver
during its first pass in the portal blood through
the liver to systemic circulation

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26
Q

First Pass and Hepatic Extraction
 Drugs with low hepatic extraction will have
– first pass clearance, and vice versa

A

low

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27
Q

First pass effect occurs due to metabolism
by/in
(4)

A

 Gut bacteria
 Intestinal brush border enzymes
 Portal blood
 Liver enzymes

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28
Q

Hepatic Extraction
 Low extraction
(2)

A

 Low first pass
clearance
 Change in hepatic
enzymes won’t have
significant effect on
first pass clearance

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29
Q

High extraction
(2)

A

 Hight first pass
clearance
 Changes in enzyme
function will have large
effect on first pass
effect

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30
Q

Enteral administration
ADVANTAGES
(4)

A

 Most common route
 Safest
 Easiest
 Most economical

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31
Q

Enteral administration
DISADVANTAGES
(5)

A

 Limited absorption
 Emetogenic potential
 Subject to first pass
 Absorption may be
affected by food or other
drugs
 Irregularities in
absorption or propulsion

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32
Q

Parenteral Administration
ADVANTAGES
(4)

A

 Not subject to first pass
 Most rapid onset
 Ability to titrate
 Doesn’t require cooperation

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33
Q

Parenteral Administration
DISADVANTAGES
(4)

A

 Greater patient discomfort
 Requires additional training
to administer
 Concern for bacterial
contamination
 Injection-associated risks

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34
Q

Injection-associated risks (3)

A

 Extravasation
 Intra-arterial injection
 Limb loss

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35
Q

Oral Administration
 Absorption governed by:
(5)

A

 Surface area for absorption
 Blood flow to site of absorption
 Dosage form administered
 Ionization status (lipo- vs. hydrophilic)
 Concentration at site of absorption

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36
Q

Oral Administration
 Enteric coating
(2)

A

 Drugs destroyed by
gastric secretions, low
pH, or that cause
gastric irritation
 Risk of bezoar
formation

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37
Q

Oral Administration
— Release

A

Delayed

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38
Q

►Intravenous (IV): F = 100%
(2)

A

● Immediate onset, Bypasses GI absorption
● Best for emergencies

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39
Q

Intramuscular (IM): 75-100%
(3)

A

● Irritating drugs given this route
● Not as rapid response as IV
● Depot preparations (sustained release) ie., suspensions, ethylene glycol,
peanut oil- all slow down absorption.

40
Q

►Subcutaneous (SQ): 75-100%
(3)

A

● Slower absorption than IV or IM
● Little risk of intravascular injection
● Examples: Insulin, Mechanical pumps, heparin (DVT prophylaxis)

41
Q

► Intradermal (ID):
(2)

A

● Small amounts of drug
● Tuberculosis skin test, Local anesthetics

42
Q

► Inhalation: 5-100%
(3)

A

● Almost as rapid as IV. (Method of abuse)
● Delivered directly to lung (good selectivity)- minimal systemic side-effects.
● Gases, aerosols of solutions & powders -good for respiratory conditions.

43
Q

► Intranasal: 5-100%
(2)

A

● Vasopressin for tx of diabetes insipidus, calcitonin (osteoporosis).
● Method of drug abuse.

44
Q

►Intrathecal/Epidural:
(1)

A

● Subarachnoid space of spinal cord – into CSF (Lumbar puncture- Baclofen
in MS, regional anesthetic in delivery, morphine drip)

45
Q

►Topical: Skin, oral mucosa, sublingual, rectal (avoids 50% of 1st pass metab)
((3)

A

● When local effect is desired-but can provide systemic effects.
● Sublingual (100%), rectal (50%) bypasses liver- good bioavailability.
● Transdermal Controlled Release- Scopolamine, nitroglycerin, nicotine,
estrogens (BCP), fentanyl.

46
Q

►Subgingival:

A

Perio specific uses: doxycycline(Atridox); minocycline(Arestin)

47
Q

Distribution
 The administered drug leaves the blood
stream and enters other “compartments”
 Dependent upon:
(3)

A

 Cardiac output
 Capillary permeability
 Blood flow

48
Q

Kidney: – mL/min/100gm
Liver: – mL/min/100gm
Heart: – mL/min/100gm
Brain: – mL/min/100gm

A

360
95
70
55

49
Q

 Central

A

 Well perfused organs and tissues (heart, blood, liver, brain, kidney). Drug equilibrates rapidly.

50
Q

 Peripheral

A

 Less well perfused organs/tissues (adipose, skeletal muscle, etc.)

51
Q

 Special compartments

A

 CSF, CNS, pericardial fluid, bronchial secretions, middle ear

52
Q

Protein binding
 Albumin –
 α-glycoprotein –

A

acidic drugs
basic

53
Q

SKIPPED
Distribution
(5)

A

 Protein binding
 Free vs. bound
 Competition
 Disease impact
 Drug levels

54
Q

Distribution
 Accumulation in tissue
(4)

A

 Organs
 Muscle
 Adipose
 Bone

55
Q

Distribution
 Redistribution
(2)

A

 From site of action into other
tissues or sites
 E.g. propofol

56
Q

CNS
(3)

A

 Blood brain barrier
 Efflux transporters
 Inflammatory
processes

57
Q

SKIPPED
 Blood brain barrier
(2)

A

 Lipid solubility
 Clinical effects

58
Q

Volume of Distribution (Vd)
(2)

A

 Volume of fluid in which a drug would
need to be dissolved to have the same
concentration in plasma. Doesn’t
represent “real” volume
 Relationship between dose and resulting
Cp

59
Q

 Lipophilic drugs tend to have a – Vd
 Protein bound drugs have — Vd

A

larger
lower

60
Q

Drugs with a Vd of:
 < 5L:
 5-15L:
 > 42L:

A

Confined to plasma
Distributed to extracellular fluid (RBCs + plasma)
Distributed to all tissues in the body, especially adipose

61
Q

 increase Vd =

A

increase likelihood that drug is in the tissue

62
Q

increase Vd =

A

decrease likelihood that drug is confined to the circulatory system

63
Q

Metabolism
 Removal
(2)

A

 Either metabolized/biotransformed and
eliminated or excreted unchanged
 Must be water-soluble to be removed

64
Q

Lipid solubility good for — and
—, bad for —

A

absorption, distribution
excretion

65
Q

Metabolism
 Process of biotransformation
(2)

A

 Converts drugs into polar metabolites
 Lipophilic into hydrophilic

66
Q

Liver does the heavy lifting

A

 P-450

67
Q

Cytochrome P-450 system
(2)

A

 70+ forms
 Liver, kidney, intestines

68
Q

Metabolism – Phase I
(4)

A

 Catabolic
 Exposes functional group on parent compound
 Usually results in loss of pharmacologic activity
 Activation of prodrugs

69
Q

Metabolism and P450 Interaction
(3)

A

 Substrates
 Inhibitors
 Inducers

70
Q

Genetic Polymorphisms

A

 Genetic variability in function of CYP
isoenzymes

71
Q

Genetic variability in function of CYP
isoenzymes
May be poor metabolizers (PM) or rapid
metabolizers (RM), leading to:
(2)

A

 Subtherapeutic effect: CYP2D6 PM – codeine,
tramadol
 Toxicity: CYP3A4 – diazepam, alprazolam
(insufficient activity in some Asian populations)

72
Q

Phase II
(3)

A

 Occurs after functional groups are exposed
 Anabolic: adds water soluble molecules to
structure
 Much less interpatient variability

73
Q

Phase II
 Major reactions
(4)

A

 Glucuronidation
 Glutathione conjugation
 Sulfate conjugation
 Acetylation

74
Q

Excretion
(3)

A

 Removal of unchanged drug
 Kidney, lung, feces – primary routes
 Polar compounds > lipid soluble
compounds

75
Q

Excretion kidney
 3 processes
(3)

A

 Glomerular filtration
 Active tubular secretion
 Passive tubular reabsorption

76
Q

Excretion- kidney
 Dependent upon
 Only — drug filtered
 Non-ionized weak acids and bases
 Alkaline urine “traps”

A

renal function
unbound
passively reabsorbed
ionized, acidic molecules, increases excretion

77
Q

Excretion- lungs
(2)

A

 Primarily inhaled
anesthesia or volatile
liquid
 Affected by
respiratory rate and
blood flow

78
Q

Excretion- feces
 Unabsorbed
 Metabolites excreted
in the
 Un-reabsorbed
metabolites secreted
into the

A

orally
administered meds
bile
intestinal
tract

79
Q

 Drugs have to cross

A

lipid membranes, can do this by passive (with the concentration gradient) or active (against the gradient) transport

80
Q

 — is main factor that determines rate of passive transport

A

Lipid solubility

81
Q

 Only — drugs can diffuse across lipid membrane

A

uncharged

82
Q

 Partition –

A

acids get trapped in basic environments, vice versa

83
Q

 — most prominent re: protein
binding; binds acidic drugs (~2
molecules/albumin)

A

Albumin

84
Q
A

elimination

85
Q

 Competition for protein binding can
sometimes lead to —

A

interactions

86
Q

 Drugs with low — are not well
absorbed from the gut

A

lipid solubility

87
Q

Gut absorption depends on factors such as:
(4)

A

GI motility,
GI pH,
particle size,
interaction w/ gut contents

88
Q

 — is fraction of dose that
makes it to systemic circulation to elicit an
effect

A

Bioavailability (F)

89
Q

 Phase I reactions are

A

catabolic; involves oxidation, reduction, and hydrolysis

90
Q

 Phase I prepares the drug for Phase II, can result in more active products; often involves

A

P450 system

91
Q

 Phase II reactions are

A

anabolic, conjugated, leaving inactive and polar product for excretion

92
Q

 — induction and inhibition are hugely important concepts regarding drug interaction

A

P450

93
Q

 Unless they’re protein bound, most drugs are
filtered through the —

A

glomerulus

94
Q

 Weak acids and bases are actively secreted
into the

A

renal tubule

95
Q

 Lipid soluble drugs are

A

passively reabsorbed,
not efficiently excreted

96
Q

 Can use pH partition concept to facilitate

A

excretion of certain drugs

Pharmacology (13 decks)

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