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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

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

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