chapter 1 pharmacology Flashcards
(94 cards)
1
Q
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
A
pharmacology
2
Q
Area of pharmacology concerned with the
use of chemicals in the prevention, diagnosis,
and treatment of disease, especially in humans
A
MEDICAL PHARMACOLOGY
3
Q
Area of pharmacology concerned with the
undesirable effects of chemicals on
biologic systems
A
TOXICOLOGY
4
Q
Identifies the exact mechanism of action
of one particular drug
Identifies the receptors
A
MOLECULAR BIOLOGY
5
Q
Any substance that brings about a change
in biologic function through chemical actions
A
DRUG
6
Q
Specific molecule in the biologic system that
plays a regulatory role
A
receptor
7
Q
Drugs are given at a site ___________ from the
intended site of action
A
distant
8
Q
general range of drug size
A
100 - 1000
9
Q
MW For selective binding
A
100
10
Q
MW For traversing to different barriers of the body
A
1000
11
Q
MW
Cannot move within the body
Given directly at the site of action
A
> 1000
12
Q
Chemical forces or bonds through which the drug interacts with the receptors Weaker bonds are more selective bonds
A
DRUG RECEPTOR BONDS
13
Q
DRUG RECEPTOR BONDS
Strongest
Irreversible
A
COVALENT
14
Q
DRUG RECEPTOR BONDS
More common
Weaker
Eg, between cation and an anion
A
ELECTROSTATIC BONDS
15
Q
DRUG RECEPTOR BONDS
Weakest
Highly lipid soluble drug
A
HYDROPHOBIC BONDS
16
Q
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)
A
administration- action
17
Q
Movement of drug molecules into and within
the biologic environment
A
PERMEATION
18
Q
Movement of molecules through the watery
extracellular and intracellular spaces
A
AQUEOUS DIFFUSION
19
Q
aqueous diffusion is a passive or active process?
A
passive
20
Q
AQUEOUS DIFFUSION is governed by
A
Governed by Fick’s law
21
Q
where does aqueous diffusion take place? (membranes of ….)
A
Membranes of capillaries with small waterfilled pores
22
Q
Movement of molecules through membranes
and other lipid structures
A
lipid diffusion
23
Q
type of diffusion
Most important factor for drug permeation
A
lipid diffusion
24
Q
LIPID DIFFUSION is governed by
A
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
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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
Concentration of such drugs in plasma
decrease in linear fashion over time
With higher doses, there will be bigger
chances of toxic effect because the patient
may not be able to eliminate it
Eg, alcohol, phenytoin, aspirin
ZERO ORDER ELIMINATION
