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PHARM 124 > Suspension > Flashcards

Suspension Flashcards

1
Q

Define Suspensions

A

a coarse dispersion containing
finely divided insoluble particulate material suspended in a
liquid or semisolid medium

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2
Q

What are the criteria for suspensions (particles)

A

are uniformly distributed
have minimal solubility in the continuous phase

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3
Q

What are the criteria for suspensions (size)

A

the size distrubution of the particles ranges from 1-100 um (diameter)

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4
Q

What is the size (um) of fine dispersion?

A

1-50 um

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5
Q

What is the size (um) of coarse dispersion?

A

50-100 um

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6
Q

List some of the advantages of suspensions?

A

Deliver poor water-soluble drugs
Suitable for patients with difficulty in swallowing a tablet or capsule
Palatability (masking taste)
Chemical stability (hydrolysis,…)
Sustained Release
Can be given for both systemic (antibiotics) and local therapeutic effects (activated charcoal to adsorb excess GI fluid)

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7
Q

What are some disadvantages of suspesions?

A

Physical instability, settling over time results in lack of uniformity of the dose

Manufacturing Difficulties

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8
Q

List some requirement of acceptable suspensions

A

Should not precipitate rapidly
Redispersed quickly by shaking
Correct viscosity to pour from the bottle/flow through an administration needle
For topical formulations sufficiently fluid to spread over the skin

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9
Q

What are the two types of internal phase?

A

hydrophilic solids
hydrophobic solids

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10
Q

List some examples of hydrophilic solids in internal phase

A

clays (kaolin, talc, magnesium aluminum silicate)
hydroxides and oxides of calcium, magnesium, zinc, aluminum & titanium

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11
Q

List some examples of hydrophobic solids in internal phase

A

most pharmaceutical substances: charcoal, sulfur, aspirin, phenobarbital

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12
Q

List some factors that are used for selection of external phase (medium)

A

safety
density
viscosity (for stability)
taste
stability

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13
Q

What types of external phase are used in suspension?

A

polar liquid
non-polar liquid
structured vehicles

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14
Q

List some examples of polar liquids used in suspensions

A

water
alcohol
polyols (glycerin)
glycols (propylene glycol)
simple syrup
cherry syrup
sorbitol solution

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15
Q

List some examples of non polar liquids used in suspensions

A

oils
fatty esters
hydrocarbons

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16
Q

List some examples of structured vehicles used in suspensions

A

acacia
tragacanth
carbopol
methylcellulose derivatives
colloidal silicon dioxide

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17
Q

T/F Is water the only external phase that can be used up to 100%

A

False non polar can too

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18
Q

What is the percentage that polymer can be in the final composition for structured vehicles?

A

0.5-5%

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19
Q

What is the percentage can be used for the following?
water
simple syrup
cherry syrup

A

up to 100%
50-100%
50-100%

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20
Q

What are the two roles that structured vehicles can be based on concentration?

A

protective colloids at low concentration
viscosity-inducing agents at higher concentration

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21
Q

Describe thixotropic behavior

A

by stirring or shaking will decrease viscosity

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22
Q

T/F Structured Vehicles can be used for parenteral administration

A

False they can not as there is an issue with syringeability

23
Q

What other important ingredients in suspensions?

A

suspending (flocculating) agents
viscosity modifiers

24
Q

What are the characteristics important for suspending agents?

A

electrolytes
ionic surfactants
polymeric flocculating agents

25
Q

What are the characteristics important for viscosity modifiers?

A

polysaccharides
water soluble cellulose derivatives
hydrated silicates
acrylic acid polymers
colloidal silicon dioxide

26
Q

What does electrolytes do?

A

They help to deflock the particles
by reducing the zeta potential
(stop them from clumping)

27
Q

What does the ionic surfactants do?

A

they reduced the capable of zeta potential

28
Q

What does polymeric flocculating agents do?

A

form a gel like network to cross link the suspended particles
also increase viscosity

29
Q

What is polysaccharides used for? Why?

A

only for extemporaneous compounding

because of their increased susceptibility to microbial growth

30
Q

List some examples of polysaccharides used for suspensions

A

acacia gum
tragacanth
alginates

31
Q

How do water soluble cellulose derivatives work in suspensions?

A

make greater viscosity ranges available by combining agents in specific proportions

32
Q

List some examples of water soluble cellulose derivatives

A

methylcellulose
microcrystalline cellulose

33
Q

List an example of hydrated silicates

A

bentonite

34
Q

How do acrylic acid polymers?

A

HIgh molecular weight cross linked polymers of acrylic acid form gels in neutralized aqueous dispersions

35
Q

Give an example of acrylic acid polymers

A

carbopol

36
Q

Explain colloidal silicon dioxide

A

fluffy white powder used as either a suspending/thickening agent or a tablet/capsule diluent

37
Q

List the suspension types based on pharmaceutical application

A

oral
topical
parenteral
sterile topical
cosmetics

38
Q

List the suspension types based on physical structures

A

deflocculated
flocculated

39
Q

List some properties of an ideal suspending agent modifier

A

readily dissolved/dispersed without special techniques
readily and uniformly incorporated
ensures formulation of loosely packed system
no effect on bioavailability of the drug
no incompatibilities
stability over wide pH range

40
Q

Examples of oral suspensions

A

antibiotics
antacids
radiopaque suspensions

41
Q

Examples of topical

A

calamine lotions

42
Q

Examples of parenteral suspensions

A

I.M
S.C
intralesional
intraarticular

43
Q

Examples of sterile topical suspensions

A

ophthalmic suspensions

44
Q

List some properties of well formulated suspensions

A

must be easily resuspendable
after shaking the dispersed phase is suspended long enough to remove a dose
particles should be sufficiently small to appear smooth
has suitable viscosity

45
Q

List some properties of deflocculated suspensions

A

cloudy and slow to settle
caking at the bottom after long term of settlement

46
Q

List some properties of flocculated suspensions

A

form loose aggregates (clumps)
particles settle as flocs
rate of sedimentation is relatively rapid
“fluffy”

47
Q

What are some compounding tips?

A

dust masks should be worn
aerosolizing powders make them easier to work with, or adding a few drops of alcohol, water or mineral oil

48
Q

Define high zeta potential

A

repulsive forces > attractive forces
system will be dispersed or deflock
upon settling the suspension will cake –> difficult to resuspend

49
Q

Define lower zeta potential

A

attractive forces > repulsive forces
system will be flocc (prevent caking)

50
Q

What are the three factors of uniform dispersion of deflocculated particles?

A

incorporation of structured vehicle
addition of flocculating agent
addition of flocculating agents

51
Q

Why is incorporation of structured vehicle important?

A

deflocculated suspension in structured vehicle as final product

52
Q

Why is addition of flocculating agent important?

A

flocculated suspension as final product

53
Q

Why is addition of flocculating agents important?

A

flocculated suspension
incorporation of structured vehicle
flocculated suspension in structured vehicle as final product

PHARM 124 (14 decks)

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