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Pharmacy Practice Lab II > Lab 9 > Flashcards

Lab 9 Flashcards

1
Q

name 3 ways in which powders can be used in pharmacy practice

A

-as powder dosage forms for topical use

-pre-packed as dosage forms for other routes

-most commonly - they are processed to manufacture other dosage forms like capsules tablets, and oral inhalations or injectable powders for reconstitution

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2
Q

name 2 products that use powders as topical dosage forms

A

dusting powders and bulk powders

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3
Q

name 2 advantages of drugs administered as powders

A

they are more stable than liquid dosage form

they have a short onset time (bc they dont need to disintegrate)

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4
Q

name 5 disadvantages of powders

A

-assuring uniformity of dosage is difficult

-may be difficult to store and convey (transfer)

-some of the total volume is made up of free space (air)

-powder particles tend to cling to each other and form clusters

-not suitable for hygroscopic (able to take up moisture) and deliquiscient drugs (tend to melt)

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5
Q

when is it especially difficult to ensure uniformity of dosage in the powder dosage form?

A

when the content of the active drug is low

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6
Q

why do powder particles tend to adhere to each other to form clusters?

A

due to electrostatic forces or moisture

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7
Q

true or false

the particle size in a powder does not have to be uniform

A

false - it does

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8
Q

many of the technical difficulties with powders are related to what properties?

A

rheological/flow properties

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9
Q

flowability is dependent on….

A

physical characteristics of the powder like surface texture, particle shape, size, size distribution, cohesiveness, particle interaction, electrostatic charge and hardness

ALSO external factors like humidity, aeration, temp, work/equipment surface

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10
Q

flowability is a measure of….

A

a powder’s ability to flow freely

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11
Q

good flowability of a powder is essential for what?

A

dose accuracy
when dispensing the powder from its container into other dosage forms (tablets/capsules)

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12
Q

true or false

the flow properties/rheology of powders is affected by 100 or more factors

A

true

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13
Q

as mentioned, the flow properties of powders are affected by 100 or more factors.

what is sufficient to understand the flow behavior of powders?

A

testing a single factor is inadequate.

testing a few factors is sufficient to understand the flow properties

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14
Q

define angle of repose.
what is the symbol for it

A

symbol = theta

the maximum internal angle between the surface of the conical/sloping and the horizontal surface for a free flowing powder pilee

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15
Q

the angle of repose is used to evaluate what?

A

the flow properties of the powder.

corresponds to inter-particulate friction or resistance of movement between the powder particles

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16
Q

angle of repose depends on…..

A

density of the powder
moisture content
particle size
porosity
surface area and shape of the particles
friction/interaction between the particles

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17
Q

the angle of repose ranges from….

A

0-90 degrees

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18
Q

the HIGHER the angle of repose, the _____ the flow properties

A

WORSE

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19
Q

true or false

a low angle of repose indicates better flow properties

A

true

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20
Q

what is the angle of repose of free flowing solids?

what about poor flowing powders?

A

free flowing solids = 20 degrees or lower

poor flowing powders = 40 degrees or higher

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21
Q

generally ____ particles have a low angle of repose

(small or large? give specific size)

A

large particles greater than 100mm

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22
Q

the angle of repose _____ with increasing concentration of the poorest flowing ingredient

A

increases

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23
Q

what was used in the lab to measure the angle or repose?

A

a fixed base diameter

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24
Q

type of flow and powder if angle of repose is less than 25 degrees

A

type of flow = excellent
type of powder = non cohesive

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25
Q

type of flow and powder if angle of repose is 25-30 degrees

A

type of flow = good
type of powder = noncohesive

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26
Q

type of flow and powder if angle of repose is 30-40 degrees

A

type of flow = passable
type of powder = cohesive

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27
Q

type of flow and powder if angle of repose is greater than 40 degrees

A

type of flow = very poor
type of powder = very cohesive

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28
Q

give the formula for angle of repose

A

theta = tan-1 (h/r)

h=height of pile
r = radius of base of the pile

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29
Q

angle of spatula is a measure of…

A

the relative angle of internal friction of the powders

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30
Q

how is angle of spatula measured

A

when a spatula is inserted into a powder heap parallel to the bottom and then lifted straight up out of the material

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31
Q

true or false

the angle of repose is always greater than the angle of spatulation

A

FALSE

the angle of spatula is always greater than angle of repose EXCEPT for very free flowing powders

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32
Q

except for very free flowing powders, the angle of ____ is always higher than the angle of ____

A

angle of spatula is always higher than angle of repose

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33
Q

_______ is used as a rough estimate to determine flowability

A

angle of spatula

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34
Q

for angle of spatula, a value under ______- indicates that the powder is free flowing

A

under 40 degrees

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35
Q

a ____ powder forms a single area on the spatula whereas a ____ material forms a number of irregular angles on the blade of the spatula

A

free flowing forms a single material

non-free flowing material forms a number of irregular angles on the blade

36
Q

compressibility is a test to evaluate what? how is it done?

A

the flowability of the powder by comparing the poured (puffed) density and the tapped density of the powder

37
Q

what is bulk density

A

describes the amount of entrapped air in the powder

38
Q

bulk density =

A

mass of particles/volume of powder

39
Q

what kind of powders will have the greatest difference between their tapped and aerated bulk density?

A

powders with significant frictional and cohesive interactions

40
Q

_____ compressibility values generally indicate decreased flowability

A

high

41
Q

true or false

tapped density does not vary with the number of taps and style of tapping

A

false - it does

42
Q

give the formula for percent compressibility

A

% compressibility = tapped density - bulk density
/
tapped density

43
Q

cohesiveness describes….

A

the adherence of the powder particles to each other

44
Q

cohesiveness is dependent on what?

A

the physical and chemical nature of the powder

also influenced by particle size and moisture content

45
Q

the ____ the moisture content in a powder, the higher the cohesiveness

A

higher

46
Q

what is the oldest method of classifying powders by the size of the particles?

A

sieving

47
Q

in the sieving method of classifying powders by particle size, which sieve is on top and which is on bottom?

A

top = coarsest
bottom = finest

48
Q

what USP chapter describes specific terms to define powder fineness

A

USP 811

49
Q

Powders with ____ particles (what size?) are more likely to be non-cohesive, permeable, and have better flowability and low compressibility?

A

large particles (greater than 100 micrometers)

50
Q

what powder size is likely to be cohesive, compressible, and contain a lot of entrapped air?

A

less than 10 micrometers

51
Q

true or false

the lower the particle size, the higher the cohesiveness

A

true

52
Q

what describes the mesh size?

A

the number of openings in the mesh screen per inch

53
Q

X50 is when….

A

50% of the particles are smaller and 50% of the particles are larger than the mess size

54
Q

X90 means….

A

the particle size corresponds to 90% of cumulative undersize distribution

55
Q

X10 means….

A

the particle size at which 10% cumulative undersize distribution

56
Q

to classify a powder as COARSE, at least ___% of the % cumulative distribution must be greater than 355 microns (micrometers)

A

50%

57
Q

particle size more then 250 micrometers
describe flow properties

A

free flowing

58
Q

particle size less than 10 micrometers
describe flow properties

A

resistant to flow

59
Q

particle size 10-100 micrometers
describe flow properties

A

poor flow

60
Q

how are dusting powders dispensed?

A

either as bulk powders or in sifted top containers

61
Q

further classify dusting powders

A

may be medicinal or cosmetic – intended to be applied to skin

62
Q

explain medicinal dusting powders

A

API is mixed with a base powder.
thymol and menthol may be added for cooling sensation

63
Q

name 2 things that can be added to medicinal powders for a cooling sensation

A

thymol and menthol

64
Q

name things that can be used as inert bases for dusting powders

A

bentonite
kaolin
magnesium carbonate
starch
talc

65
Q

what do powder bases do?

A

absorb secretions and exert a drying effect

66
Q

dusting powders should be able to pass through what sieve and why?

A

100-200 mesh sieve
to ensure they are grit free and smooth to the touch - non irritating to the skin

67
Q

___ and __ powders have the tendency to absorb moisture from the atmosphere

A

hygroscopic and deliquescent

68
Q

give 3 examples of deliquescent powders. Are they able to fully dissolve?

A

can partially or fully dissolve due to the adsorbed moisture

sodium chloride
sodium bromide
pilocarpine

69
Q

name 3 strategies to avoid the adsorption of moisture by the powder dosage form

A

-add a hydrophilic but water insoluble powder that will adbsorb the water attracted by the hygroscopic/deliquescent material

-dispense product in tightly closed container and store in low humidity area

-add desiccant packets into container

70
Q

what are efflorescent powders

A

crystalline substances containing water of crystallization or hydration

71
Q

when can efflorescent powders release their water content?

A

under mechanical stress (like trituration)

in a low humidity environment

72
Q

when efflorescent powders release their water content under mechanical stress like trituration, what happens to the powder?

A

it becomes damp

73
Q

in general what is the problem with when efflorescent powders release their water of hydration or crystallization

A

a given weight of powder no longer contains the same amount of drug

74
Q

give 3 examples of efflorescent powders

A

atropine sulfate
codeine sulfate
morphine acetate

75
Q

name 2 strategies to handle efflorescent powders

A

store in tight container
substitute with anhydrous form of drug

76
Q

what are eutetic mixtures

A

solids that have the tendency to liquefy when mixed with each other
due to the depression of melting points of the materials – bc one substance acts as an impurity for the other substance

77
Q

when does the handling of eutetic mixtures pose a problem

A

when the melting point of the powder mixture is near or below room temp.
result is a paste or a liquid

78
Q

give example of eutetic mixture and their melting point

A

camphor (mp = 180 degrees c)
menthol (mp = 42 degrees c)

79
Q

how to handle eutetic mixture if:

-amount of eutetic mixture is small in the powder

-amount of eutetic liquid is large

A

if smol - the liquid can be adsorbed onto a diluent or other powder in the formulation

if large quantity - eutetic components should be mixed separately with equal amounts of the other powder ingredients – helps to avoid physical contact between the eutetic components

80
Q

what is calamine

A

a mixture of zinc oxide with about 0.5% ferric oxide or a zinc carbonate

anti itch that works via cooling sensation as it evaporates on the skin

81
Q

explain what calamine is used for

A

for mild pruritic conditions like sunburn, eczema, rashes
also dries oozing or weeping from minor skin irritation

82
Q

historically, what has calamine been used as

A

mixed with rose water to create soothing face mask

used in face powders, dusting powders (adsorbent), and toothpastes

83
Q

explain what talc is and why it’s used

A

a natural product that contains basic magnesium silicate
has sopay feeling with gives smooth tecture

useful excipient as diluent, filler, bulking agent, lubricant, glidant, adbsorbent, opacifying agent, skin protectant

84
Q

what is magnesium stearate primarily used as

A

a glidant/lubricant in the manufacture of powders, capsules, and tablets

85
Q

why is a glidant/lubricant like magnesium stearate used

A

to reduce friction between moving surfaces and improve FLOW

86
Q

what concentrations is magnesium stearate effective

A

only 0.5%-1%
ineffective at higher conc

87
Q
A

Pharmacy Practice Lab II (12 decks)

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