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Pharmaceutics II Exam 1 > part 4 > Flashcards

part 4 Flashcards

1
Q

what is a tablet direct compression excipient? give an example

A

ditab (dibasic calcium phosphate)
used in DIRECT COMPRESSION tablet formulations. saves money

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2
Q

why is a tablet disintegrant used?

A

used in SOLID DOSAGE FORMS to promote the disruption of the solid mass into smaller particles which are MORE READILY DISSOLVED/dispersed

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3
Q

give 2 popular tablet disintegrants

A

starch and avicel (microcrystalline cellulose)

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4
Q

explain how starch works as a tablet disintegrant

A

it swells when in contact with water which causes the powder to break down and ensure dissolution

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5
Q

is avicel natural or synthetic? what is it used as?

A

synthetic tablet disintegrant

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6
Q

what are tablet/capsule glidants? give 3 examples

A

used in tablet and capsule formulations to improve the FLOW PROPERTIES of the powder mixture

colloidal silica
cornstarch
talc

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7
Q

what is a tablet lubricant used for?

give 5 examples

A

used in tablet formulations to reduce FRICTION DURING TABLET COMPRESSION

calcium stearate
magnesium stearate
mineral oil
stearic acid
zinc stearate

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8
Q

without a tablet lubricant, what would happen?

A

the surface of the tablet would not be smooth

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9
Q

what are tablet/capsule opaquants used for? give an example

A

used to render a capsule or tablet coating opaque

titanium dioxide (ingredient in susnscreen_

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10
Q

tablet/capsule opaquant may be used alone or in combination with ______

A

colorant

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11
Q

how does being opaque help the tablet?

A

it blocks the light which aids in stability

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12
Q

what is the function of a tablet polishing agent?
give 2 examples

A

used to impart an attractive sheen to coated tablets

carnauba wax and white wax

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13
Q

what is the function of a tonicity agent?

A

to render a solution similar in OSMOTIC CHARACTERISTICS to physiological fluids.

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14
Q

name 3 types of preparations in which tonicity is a consideration

A

ophthalmic
parenteral
irrigation fluids

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15
Q

give 2 examples of tonicity agents

A

sodium chloride
dextrose

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16
Q

explain the difference between sodium chloride and dextrose as tonicity agents

A

osmotic pressure is related to the NUMBER OF PARTICLES.

sodium chloride produces 2 particles upon dissociation while dextrose only produces 1. therefore, 1 mol dextrose = 0.5mol NaCl.

NaCl is thus preferred because less of it is needed to accomplish the same function, but sometimes dextrose is needed in some patients for nutritional value

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17
Q

a hypotonic solution will cause a cell to….

A

burst (lyse)

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18
Q

what is the depressing freezing temp

A

0.52

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19
Q

define a vehicle

A

a carrying agent for a drug substance

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20
Q

true or false

vehicles are only used for oral preparations

A

false – oil and parenteral

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21
Q

generally, oral liquids are aqueous preparations (___________) or hydroalcoholic (__________)

A

syrups
elixirs

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22
Q

parenteral solutions for intravenous use are ______ whereas intramuscular injections are ______

A

IV = aqueous

IM may be aqueous OR oleaginous

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23
Q

how many different kinds of vehicles are there?
name them

A

3:

-flavored/sweetened
-oleaginous
-sterile

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24
Q

give 6 examples of flavored/sweetened vehicles

A

acacia syrup
aromatic syrup
aromatic elixir
cherry syrup
cocoa syrup
syrup

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25
Q

give 4 examples of oleaginous vehicles

A

corn oil
mineral oil
peanut oil
sesame oil

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26
Q

give 2 examples of sterile vehicles

A

bacteriostatic water for injection
bacteriostatic sodium chloride for injection

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27
Q

which is preferred – sterile water for injection or bacteriostatic water for injection?

A

sterile water for injection because it does not contain preservatives

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28
Q

a viscosity increasing agent is used to…..

A

change the consistency of a preparation to render it MORE RESITANT TO FLOW

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29
Q

name 3 dosage forms in which viscosity increasing agents are used

A

suspensions to slow sedimentation

ophthalmic solutions to enhance contact time (methylcellulose)

to thicken topical creams

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30
Q

name 4 factors to consider under “appearance and pallatability”

A

flavoring pharmaceuticals
sweetening pharmaceuticals
coloring pharmaceuticals
preservatives

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31
Q

true or false

preservatives kill microorganisms

A

FALSE – they inhibit their growth

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32
Q

true or false

sterilization kills microorganisms

A

true

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33
Q

What is the ideal solubility of the preservative selected?

A

it should be soluble enough in water to have adequate concentrations in the aqueous phase.
An emulsion is oil and water. The preservative has to dissolve in both phases

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34
Q

when selecting a preservative, the preservative must prevent….

A

the growth of the type of microorganisms considered the MOST LIKELY CONTAMINANTS of the preparation

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35
Q

what can you say about the ideal dissociation of the preservative selected

A

the proportion of the preservative remaining undisociated at the pH of the preparation makes it capable of

-penetrating the microorganism
-destroy its integrity

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36
Q

what are the main 3 requirements for the concentration of the preservative selected?

A

it must be nonirritating, nonsensitizing, and nontoxic to the patient

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37
Q

what are the % preservative limits for:

  1. Oral
  2. Parenteral
A

~1% for oral
~0.1% for parenteral

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38
Q

the preservative selected must have adequate stability.
explain thus further

A

it cannot be reduced in concentration by chemical decomposition or volatilization during the preparation’s shelf life

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39
Q

true or false

the preservative must be completely compatible with all other formulative ingredients and does not interfere with them, NOR do they interfere with the preservative’s effectiveness

A

true

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40
Q

true or false

it is not a requirement that the preservative selected does not adversely affect the preparation’s container/closure

A

false– it is a requirement

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41
Q

for oral preparations, do we prefer to use alcohol or preservatives?

A

alcohol

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42
Q

define:

  1. Suspensions
  2. Emulsions
  3. Foams
A

suspensions: dispersion of solid in liquid

emulsions: dispersion of liquid in liquid

foams: dispersion of gas in liquid

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43
Q

name some heterogeneous dosage forms

what does this mean?

A

suspensions. emulsions, and foams

they have 2 phases

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44
Q

what does “interface” mean

A

when phases exist together, the “interface” is the boundary between the 2 phases

45
Q

what is the term for the fact that the interface are different from those in the bulk of each phase?

A

interfacial phase (it’s its own phase)

46
Q

an emulsion is what kind of interface?

A

liquid-liquid interface

YLL

47
Q

a suspension is what kind of interface?

A

liquid-solid interface

YLS

48
Q

can solid-solid have interfacial tension?

A

YES

ex: powder API forming an interface with the powder excipients

Yss

49
Q

can gas-gas form an interface?

A

NO

50
Q

explain gas-liquid interface

A

gas-liquid
YLV

a liquid surface where the body of water is exposed to the atmosphere (ex: a lake)

51
Q

is gas-solid interface possible?

A

yes

Ysv

like gas hovering over a table top

52
Q

autoclaving is an example of….

A

sterilization

53
Q

name 6 methods of preservatives to inhibit the growth of microorganisms
(REMEMBER: NOT KILLING, INHIBITING GROWTH)

A

-partial lysis (modification of cell membrane permeability and leakage of cell components)

-lysis and cytoplasmic leakage

-irreversible clotting (coagulation) of cytoplasmic constituents (protein precipitation)

-inhibition of cell metabolism by interfering with enzyme systems/inhibition of cell wall synthesis

-oxidation of cell constituents

-hydrolysis

54
Q

1 of the modes of action for preservatives is the irreversible coagulation of cellular constituents.
give an example of this

A

protein precipitation

55
Q

name 2 ways in which preservatives can inhibit cellular metabolism

A

-interfering with enzyme systems

-inhibition of cell wall synthesis

56
Q

true or false

only the unionized form of a preservative possesses preservative capability

A

true

bc the ionized form cannot penetrate the cell membrane

57
Q

alkaline preservatives are more effective at which pH conditions?

A

alkaline conditions because they will be unionized

58
Q

define adhesive force and cohesive force

A

adhesive force = attracting force between 2 DIFFERENT molecules

cohesive force = attracting force between the SAME adjacent molecules

59
Q

differentiate between interfacial tension and surface tension.

what do they have in common?

A

interfacial tension = force per unit length existing at the interface betwen TWO IMMISCIBLE LIQUID PHASES (no gas involved)

surface tension = force per unit length existing at the interface between LIQUID-VAPOR or SOLID-VAPOR phases

BOTH are temperature dependent. if the temperature changes, the value changes

60
Q

surface tension is mainly used to refer to….

A

gas—-liquid and gas—–solid

61
Q

an emulsion is an example of interfacial tension or surface tension?

A

interfacial tension

liquid—-liquid

62
Q

explain how surface/interfacial tension is temperature dependent, using water as an example

A

at 0 degrees celsius, the surface tension is 76.5 dynes/cm
-this means it requires higher energy for the water to evaporate

-at 20 degrees celsius it gets a little easier to evaporate with a surface tension of 72.8 dynes/cm

-HOWEVER, at very high temperatures (75 degrees C), the tension lowers to 63.5 dynes/cm, meaning it’s very easy for the water to evaporate

63
Q

in the case of water, as temperature increases, surface/interfacial tension___________

A

decreases

64
Q

true or false

surface tension is a constant and only a change in temperature can change the value

A

TRUE

65
Q

Which substance has a VERY HIGH interfacial tension against water? what does this mean?

A

mercury — 375 dynes/cm against water

this means that mercury doesn’t normally have interaction with water. it needs very high energy input to interact with water

66
Q

which will have HIGHER surface area in water – oleic acid or mercury?
why?

A

oleic acid will have a higher surface area than mercury in water

this is bc mercury has a very high interfacial tension with water (375) and oleic acid is small (15.6)

mercury will form a small droplet while oleic acid will most likely spread

67
Q

for emulsions, what range of interfacial tension is desirable?

A

~10-20dynes/cm

68
Q

what is the surface tension of water?
does chlorofoam have a higher or lower surface tension as compared to water? what does this mean?

A

surface tension of water = 72.8dynes/cm

chlorofoam has a LOWER surface tension at 27.1dynes/cm

this means it is easier for chlorofoam to evaporate than water. easier to go from 1 phase to another

69
Q

does olive oil have a high or low interfacial tension?

A

pretty low — 22.9dynes/cm

70
Q

what is the surface tension symbol

A

(Y) gamma

71
Q

give the formula for surface tension

A

Y= fb/2L

Y=surface tension
fb= force required to break the film

L=length of movable bar

72
Q

in the formula for surface tension, why is the L multiplied by 2?

A

because the film is double sided

73
Q

fb=….

A

m * g

where g= 981cm/sec squared

74
Q

what is the value of g constant

A

981 cm/sec squared

75
Q

what is the formula for force

A

f=Y * 2L

Y=surface tension

76
Q

give the formula for work

A

dW= f* ds

f= Y * 2L
ds=change in surface area

77
Q

surface free energy is a measure of…..

A

surface free energy change per unit area increase

78
Q

what is the formula for surface area increase

A

dA= 2L * ds

79
Q

give the formula for surface free energy

A

dW = Y * dA

Y = fb * 2L
dA = ds *2L

80
Q

if the surface tension is low, it requires ____ energy to extend the surface area

A

LESS energy

81
Q

when energy escapes, the surface area is ______

A

reduced

82
Q

name the 2 main methods for the measurement of surface and interfacial tension.

which is preferred to measure surface tension and why?

A

Capillary rise method and the DeNouy ring method

capillary rise method is preferred to measure surface tension because it is much cheaper than the alternative

HOWEVER, the capillary method can’t measure interfacial tension and the DeNouy ring method can. it is MORE PRECISE

83
Q

explain how the capillary rise method works

A

if the adhesive force (between the liquid molecules and the capillary wall) is greater than the cohesive force, the liquid wets and spreads over capillary wall. (rises).

the surface tension can then be measured (NOT INTERFACIAL)

y = 1/2 (rhp) *g

r=radius of capillary tube
h=height that the sample rises
p=density
g=constant (981cm/sec squared)

84
Q

in the capillary rise method for measuring surface tension, ___ will become constant. why?

A

h will become constant because equivalence between adhesive and cohesive force will be reached

85
Q

The deNouy ring method measures the force needed to….

A

detach a platinum-iridium ring

86
Q

what is the formula for surface tension in the DeNouy Ring method

A

Y= dial reading in dynes/2 * ring circumference

all * correction factor (given by the manufacturer)

87
Q

true or false

in very small particles, high energy exists

A

true

88
Q

if cohesive force is ____ than adhesive force, spreading will occur and a film will be formed
this exists in the case of…..

A

LESS

oleic acid and water

89
Q

when oleic acid is placed on water, how many forces exist?
name them

A

3 forces–

oleic acid - oleic acid (cohesive)

water - water (cohesive)

oleic acid - water (adhesive)

90
Q

will mercury spread on the surface of water?

A

no

91
Q

true or false

the cohesive force of mercury is very high

A

true – will not spread

92
Q

true or false

the cohesive force of oleic acid is higher than the adhesive force

A

FALSE

93
Q

which has lower surface tension – mercury or oleic acid?

A

oleic acid

94
Q

low concentration of surfactant will go where?

A

to the surface

once the surface is occupied (CMC), it will go to the bulk

95
Q

When will surfactants have NO EFFECT on reducing surface tension?

A

at concentrations above CMC (when they start to go to the bulk)

96
Q

what is duplex film?

A

thickness higher than 100 angstroms

97
Q

true or false

duplex film is independent between the surface (oleic acid/air) and the interface (oleic acid/water)

A

TRUE

98
Q

YL=…

A

surface tension of spreading liquid (top liquid)

99
Q

YS=….

A

surface tension of sublayer liquid

100
Q

YLS=…

A

interfacial tension between 2 liquids

101
Q

Wa=….

A

work of adhesion

YL+YS-YLS

102
Q

Wc=….

A

work of cohesion

2YL

103
Q

give the formula for spreading coefficient

A

S = YS-(YL+YLS)

104
Q

many _____ substances fail to spread on water (polar or nonpolar)

A

nonpolar

105
Q

what does a high S value mean?
how is S measured

A

S= initial spreading coefficient. measured in dynes/cm

high S = high spreading

106
Q

true or false

ethyl alcohol has a low S value

A

FALSE – high S value due to polar functional groups

107
Q

liquid petrolatum has a ____ S value (low or high)

A

LOW – very nonpolar

108
Q
A

Pharmaceutics II Exam 1 (9 decks)

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