Flashcards in chapter 1 pharmacology Deck (94):
1
Body of knowledge concerned with the action
of chemicals on biologic systems, especially by
binding to regulatory molecules (receptors) and
activating or inhibiting normal body processe
pharmacology
2
Area of pharmacology concerned with the
use of chemicals in the prevention, diagnosis,
and treatment of disease, especially in humans
MEDICAL PHARMACOLOGY
3
Area of pharmacology concerned with the
undesirable effects of chemicals on
biologic systems
TOXICOLOGY
4
Identifies the exact mechanism of action
of one particular drug
Identifies the receptors
MOLECULAR BIOLOGY
5
Any substance that brings about a change
in biologic function through chemical actions
DRUG
6
Specific molecule in the biologic system that
plays a regulatory role
receptor
7
Drugs are given at a site ___________ from the
intended site of action
distant
8
general range of drug size
100 - 1000
9
MW For selective binding
100
10
MW For traversing to different barriers of the body
1000
11
MW
Cannot move within the body
Given directly at the site of action
>1000
12
Chemical forces or bonds through
which the drug interacts with the
receptors
Weaker bonds are more selective
bonds
DRUG RECEPTOR BONDS
13
DRUG RECEPTOR BONDS
Strongest
Irreversible
COVALENT
14
DRUG RECEPTOR BONDS
More common
Weaker
Eg, between cation and an anion
ELECTROSTATIC BONDS
15
DRUG RECEPTOR BONDS
Weakest
Highly lipid soluble drug
HYDROPHOBIC BONDS
16
To reach its receptors and bring about biologic
effect
A drug molecule (eg, sedative) must
travel from the site of __________
(eg, gastrointestinal tract) to the site
of ________ (eg, brain)
administration- action
17
Movement of drug molecules into and within
the biologic environment
PERMEATION
18
Movement of molecules through the watery
extracellular and intracellular spaces
AQUEOUS DIFFUSION
19
aqueous diffusion is a passive or active process?
passive
20
AQUEOUS DIFFUSION is governed by
Governed by Fick’s law
21
where does aqueous diffusion take place? (membranes of ....)
Membranes of capillaries with small waterfilled pores
22
Movement of molecules through membranes
and other lipid structures
lipid diffusion
23
type of diffusion
Most important factor for drug permeation
lipid diffusion
24
LIPID DIFFUSION is governed by
Governed by Fick’s law
25
LIPID diffusion is a passive or active process?
PASSIVE
26
TYPE OF PERMEATION
Drugs transported across barriers by
mechanisms that carry similar endogenous
substances
Capacity limited
TRANSPORT BY SPECIAL CARRIERS
27
IS TRANSPORT BY SPECIAL CARRIERS GOVERNED BY FICK'S LAW
NO
28
TRANSPORT BY SPECIAL CARRIERS
TYPES OF TRANSPORT
ACTIVE TRANSPORT
FACILITATED DIFFUSION
29
No energy required
Downhill
FACILITATED DIFFUSION
30
Needs energy
Against a concentration gradient
ACTIVE TRANSPORT
31
type of permeation
Binding to specialized components
(receptors) on cell membranes
Internalization by infolding of the area of
the membrane and contents of the vesicle
are subsequently released into the cytoplasm
endocytosis
32
type of permeation
Permits very large or very lipid-insoluble
chemicals to enter the cell
Eg, B12 with intrinsic factor and iron with
transferrin
endocytosis
33
Reverse process
Expulsion of membrane-encapsulated
material from the cell
EXOCYTOSIS
34
Predicts the movement of molecules across
a barrier
FICK’S LAW OF DIFFUSION
35
Drug absorption is faster in organs with
______ (eg, small intestine)
than from organs with ______________ (eg, stomach)
larger surface areas
smaller absorbing
areas
36
Drug absorption is faster from organs with
(eg, lungs) than
those with (eg, skin)
thin membrane barriers
thick barriers
37
fick's law
measure of the mobility
of the drug in medium of the diffusion path
Permeability coefficient
38
fick's law
(length of the diffusion path)
Thickness
39
a function of the electrostatic charge (degree of ionization,
polarity) of the molecule
Aqueous solubility
40
Water molecules are attracted to ------ forming an aqueous shell
around them
charged
drug molecules
41
------- solubility of a molecule is inversely proportional to its charge
lipid
42
lipid solubility of a molecule is ------ proportional to its charge
inversely
43
Many drugs are ---- bases or ---- acids
weak
44
determines the fraction of molecules charged (ionized) versus uncharged
(nonionized
pH of the medium
45
Fraction of molecules in the ionized state can
be predicted by means of the
H-H equation
46
Neutral molecule that can form a cation
(+ charged) by combining with a proton
(hydrogen ion)
WEAK BASE
47
Ionized, ----- polar, ---- water soluble
when they are protonated
more
48
Neutral molecule that can reversibly
dissociate into an anion (- charged) and
a proton ( hydrogen ion)
Not ionized, less polar, less water soluble
when they are protonated
WEAK ACID
49
base
charged,
more water-soluble
protonated weak base
50
base
uncharged,
more lipid soluble
unprotonated weak base
51
acid
uncharged,
more lipid soluble
protonated weak acid
52
acid
charged,
more water-soluble
unprotonated weak acid
53
Clinically important when it is necessary
to estimate or alter the partition of drugs
between compartments of different pH
Henderson-Hasselbach Equation
54
When a patient takes an overdose of a weak
acid drug, excretion maybe accelerated by
alkalinizing the urine
55
Weak acids dissociate to its
in alkaline urine and cannot readily diffuse back
from the renal tubule back to the blood
charged, polar form
56
amount absorbed into the systemic circulation /
amount of drug administered
BIOAVAILABILITY
57
ROUTES OF ADMINISTRATION
Maximum convenience
Absorption maybe slower, and less complete
1. ORAL (swallowed)
58
Some drugs have low bioavailability when
given
orally
59
Subject to first-pass effect
oral administration
60
(significant amount
of the agent is metabolized in the gut wall,
portal circulation, and liver before it reaches
the systemic circulation)
first pass effect
61
ROUTES OF ADMINISTRATION
Instantaneous and complete absorption
Bioavailability by definition is 100%
Potentially more dangerous, high blood
levels reached if administration is too rapid
2. INTRAVENOUS (IV)/PARENTERAL
62
ROUTES OF ADMINISTRATION
Absorption is often faster and more complete
(higher bioavailability) than oral
Large volumes (>5 ml into each buttock) if the
drug is not irritating
3. INTRAMUSCULAR (IM)
63
First-pass effect is avoided
Heparin cannot be given by this route,
causes bleeding in the ---
INTRAMUSCULAR (IM)
64
ROUTES OF ADMINISTRATION
Slower absorption than IM route
First-pass effect is avoided
Heparin can be given by this route, does
not cause hematoma
4. SUBCUTANEOUS
65
(in the pouch between gums
and cheeks or under the tongue)
Permits absorption direct into the systemic
circulation, bypassing hepatic portal circuit
and first-pass metabolism
BUCCAL AND SUBLINGUAL
66
ROUTES OF ADMINISTRATION
Slow or fast depending on formulation of
the product
BUCCAL AND SUBLINGUAL
67
ROUTES OF ADMINISTRATION
Partial avoidance of first-pass effect
(not completely as the sublingual route)
Suppositories tend to migrate upward in
the rectum where absorption is partially
into the portal circulation
6. RECTAL (suppository)
68
ROUTES OF ADMINISTRATION
Larger amounts of unpleasant drugs
are better administered -----
May cause significant irritation
6. RECTAL (suppository)
69
ROUTES OF ADMINISTRATION
For respiratory diseases
Delivery closest to the target tissue
Results into rapid absorption because of
the rapid and thin alveolar surface area
7. INHALATION
70
Drugs that are gases at room temperature
(eg, nitrous oxide), or easily volatilized
(anesthetics)
Drugs that are gases at room temperature
(eg, nitrous oxide), or easily volatilized
(anesthetics)
7. INHALATION
71
ROUTES OF ADMINISTRATION
Application to the skin or mucous membrane
of the eye, nose, throat, airway, or vagina
for local effect
8. TOPICAL
72
ROUTES OF ADMINISTRATION
Rate of absorption varies with the area
of application and drug’s formulation
Absorption is slower compared to other
routes
8. TOPICAL
73
ROUTES OF ADMINISTRATION
Application to the skin for systemic effect
Rate of absorption occurs very slowly
First-pass effect is avoided
9. TRANSDERMAL
74
Influences absorption from IM, subcutaneous,
and in shock
BLOOD FLOW
75
High blood flow maintains a --- drug depotto-blood concentration gradient
Maximizes absorption
high
76
Concentration gradient
Major determinant of the rate of absorption
(Fick’s law)
concentration
77
DETERMINANTS OF DISTRIBUTION
determines the concentration
gradient between blood and the organ
Eg, skeletal muscle and brain
1. Size of the organ
78
DETERMINANTS OF DISTRIBUTION
Important determinant of the rate of uptake
2. Blood flow
79
Well-perfused organs
Brain
Heart, kidneys
Splanchnic organs
80
If the drug is ____ in cells, the
concentration in the perivascular space
will be ______ and diffusion from the vessel
into the extravascular tissue will be facilitated
very soluble
lower
81
DETERMINANTS OF DISTRIBUTION
---- of drugs to macromolecules in
the blood or tissue compartment will tend
to increase the drug’s concentration in that
compartment
Binding
Binding
82
Amount of drug in the body to the
concentration in the plasma
APPARENT VOLUME OF DISTRIBUTION
83
METABOLISM OF DRUGS
Action of many drugs is terminated before they
are excreted
Metabolized to biologically inactive derivatives
Conversion to a metabolite is a form of
elimination
AS MECHANISM OF TERMINATION OF
DRUG ACTION
84
METABOLISM OF DRUGS
Inactive as administered and must be
metabolized in the body to become active
Eg, levodopa, minoxidil
Many drugs are active as administered
and have active metabolites as well
Some benzodiazepines
AS MECHANISM OF DRUG ACTIVATION
PRODRUGS
85
METABOLISM OF DRUGS
Drugs not modified by the body
Continue to act until they are excreted
Eg, lithium
DRUG ELIMINATION WITHOUT
METABOLISM
86
Determinants of the duration of action for most
drugs
Dosage
Rate of elimination following the last dose
Disappearance of the active molecules
from the bloodstream
87
Are Drug elimination and drug excretion similar
NO.
A drug maybe eliminated by metabolism
long before the modified molecules are
excreted from the body
88
For most drugs, excretion is by way of the ------
(except -------)
kidneys
anesthetic gases-lungs
89
For drugs with active metabolites
(eg, diazepam), elimination of the parent
molecule by metabolism is not synonymous
with
termination of action
90
For drugs that are not metabolized,----
is the mode of elimination
EXCRETION
91
Rate of elimination is proportionate to the
concentration (ie, the higher the concentration,
the greater the amount eliminated per unit
time)
Drug’s concentration in plasma decreases
exponentially with time
A. FIRST ORDER ELIMINATION
92
Half-life of elimination is constant regardless
of amount of drug in the body
Concentration of such drug in the blood will
decrease by 50% for every half-life
Most common process
Followed by most drugs
FIRST ORDER ELIMINATION
93
Rate of elimination is constant regardless
of concentration
Occurs with drugs that saturate their
elimination of mechanism at concentrations
of clinical interest
ZERO ORDER ELIMINATION
94