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Compounding Exam 2 > Suspensions > Flashcards

Suspensions Flashcards

1
Q

suspensions are ____ phase systems:

A

2 phase

finely divided solid dispersed in a liquid medium

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2
Q

a pharmaceutical suspension is a ____ dispersion in which the internal phase is dispersed uniformly throughout the external phase

A

COARSE

solute is greater than 1 micron

(usually in compounding it’s around 400microns, and for commercial suspension it’s 3 microns)

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3
Q

how is the internal phase of insoluble solid particles maintained uniformly throughout the suspending vehicle??

A

1 or more suspending agents

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4
Q

true or false

suspensions are better at overcoming disagreeable taste than solutions

A

TRUE

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5
Q

which has faster rate of absorption - suspension or solution?

A

SOLUTION

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6
Q

True or false

some drugs are chemically unstable in solution but stable when suspended

A

TRUE

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7
Q

true or false

suspensions are only given by oral route

A

FALSE

can be externally applied or parenteral (ie - IM injection)

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8
Q

differentiate between dilute vs concentrated suspensions

A

dilute - 2-10% w/v of solid

concentrated - 50%w/v solid

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9
Q

how can suspensions be classified based on the proportion of solid particles

A

dilute or concentrated suspensions

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10
Q

3 ways suspensions can be classified by the SIZE of the solid particles

A

colloidal suspension (less than 1 micron)

coarse suspension (for compounded - 400 microns, for commercial ~3 microns)

nano suspension - 100-200nm

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11
Q

how can suspensions be classified based on the electro-kinetic nature of the particles

A

flocculated and deflocculated

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12
Q

name the 2 forms that suspensions are available in

A

ready to use suspensions and dry powder for suspension

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13
Q

how can you tell if a suspension is ready to use or a dry powder for suspension just by looking at the label?

A

“FOR ORAL SUSPENSION” indicates it is a dry powder for suspension

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14
Q

as recap, alcohol limits by age

A

less than 6 yrs old = <0.5%

6-12 yrs = <5%

children greater than 12yrs = <10%

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15
Q

true or false

essences and spirits cannot be given to pediatrics

A

TRUE

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16
Q

3 reasons why alcohol content limited for pediatrics

A

can alter liver function

cause gastric irritation

affect neurological depression

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17
Q

true or false

suspensions are not thermodynamically stable

A

TRUE

this is a disadvantage

bc of physical instability, they tend to settle over time and have lack of uniformity when dosing - MUST SHAKE WELL BEFORE USE

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18
Q

which are more CHEMICALLY stable - drugs in solution or drugs in suspension?

A

suspension

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19
Q

true or false

***drugs in suspension exhibit faster rate of absorption than many other dosage forms

A

TRUE

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20
Q

***rank the following by rate of absorption

capsule
coated tablet
suspension
compressed tablet
solution

A

FASTEST - solution
suspension
capsule
compressed tablet
SLOWEST - coated tablet

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21
Q

true or false

suspensions can mask the bad taste of a drug

A

TRUE

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22
Q

true or false

suspensions cannot be given as IM injections of depot therapy

A

FALSE - they can

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23
Q

true or false

a disadvantage of suspensions is that they are difficult to formulate

A

TRUE

bc they need wetting agent, suspending agent, etc

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24
Q

true or false

uniform and accurate dosing is easy to achieve with suspensions, and this is an advantage

A

FALSE

hard to achieve (UNLESS they are packed in unit dosing)

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25
Q

a disadvantage of suspensions is that they may be unpleasant to patients why?

A

bc of the texture

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26
Q

true or false

suspensions are bulky and hard to handle and transport

A

true

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27
Q

_____ viscosity for suspensions enhances physical stability

how?

A

HIGH

bc the particles settle slower

28
Q

name the 2 types of flow

A

newtonian flow and non-newtonian flow

29
Q

name the types of newtonian/non-newtonian fluids

A

newtonian - water/ethanol/olive oil/etc

non-newtonian - plastic flow/pseudoplastic flow/dilatant flow

30
Q

most pharmaceutical fluids (IE - suspensions, emulsions, and gels) exhibit what flow

A

NONNEWTONIAN FLOW - PSEUDOPLASTIC

31
Q

differentiate between what newtonian vs non-newtonian flow means

A

for NEWTONIAN fluids, viscosity will NOT change but will move when you heat it

for NONNEWTONIAN FLUIDS - the viscosity varies with the rate of sheer

32
Q

“shear stress-dependent flow”

newtonian or non-newtonian

A

NON NEWTONIAN

33
Q

Bingham flow is also known as…

A

plastic flow

34
Q

explain how plastic (bingham) flow works

A

the bingham bodies do NOT begin to flow until a shearing stress (corresponding to the YIELD VALUE) has been exceeded

-have to shake well enough in order for flow (movement) to occur

35
Q

what are bingham bodies vs liquids

A

substances that have a YIELD VALUE as solids

yield value must be met before flow

liquids will flow at the smallest yielding stress and have NO yield value

36
Q

why does a “yield value” exist for plastic flow

A

bc of the van der waals forces holding the flocculated particles together
-these forces must be broken down before flow can occur!

37
Q

the more flocculated the suspension, the _____ the yield value

A

HIGHER

38
Q

true or false

if a product has a very high yield value, it will run easily

A

FALSE - low yield value will run easily

39
Q

what flow is “shear-thinning system”

A

pseudoplastic flow

40
Q

explain what pseudoplastic flow is

is it desired?

A

YES - ideal flocculated suspension exhibits pseudoplastic flow

as you give more and more shearing stress, the slope increases and the molecules move faster and faster until it becomes thin and runny. the long chain molecules will line up in 1 direction to move really fast

41
Q

______ behavior is important for topical products

why?

A

pseudoplastic

when the viscosity decreases with stress, makes it easier to squeeze the product out of the container and to rub the product on large area of skin

42
Q

in pseudoplastic flow, the long chain molecules (when put under stress) line up in what direction?

A

the direction of the flow

makes thin and runnt

43
Q

what kind of flow is “shear-thickening systems”

is it desired?

A

dilatant flow

NOT ideal for suspensions. it’s the opposite of pseudoplastic flow

thickens and moves LESS as you apply more and more stress

44
Q

_______ pharmaceutical materials may solidify under the conditions of high shear, damaging the equipment

A

DILATANT

ie - pushing IM injection - the suspension will thicken with the stress and not come out

45
Q

when sheared, dilatant suspensions ______ in volume

A

increase

46
Q

when the stress on a solidified dilatant system is REMOVED, what happens?

A

the suspension returns to its original state of fluidity

47
Q

what is Ostwald ripening

A

suspensions that have a HIGH PERCENTAGE of dispersed solids will have an increase in resistance to flow as the rate of shear increases – WILL GET BIGGER

true for dilatant suspension

48
Q

example of a household product that exhibits dilatant/shear-thickening flow

A

whipped cream

49
Q

explain how with increasing rate of shear, whipped cream begins to thicken and get larger
(dilatant flow)

A

the insoluble proteins/globules will introduce AIR POCKETS

50
Q

Explain what thixotropy is

A

when you don’t touch it, it will become thick and viscous – a gel like semisolid

however, once you shake, it will flow and become runny to be easy to pour.

when you let it sit again, it will regain viscosity but TAKES TIME TO REGAIN!!!!! this is time-dependent thixotropy. don’t want it to gain viscosity too quickly

51
Q

name 2 routes of administration that thixotropic suspensions and emulsions can be used for and why

A

IM injections and nasal sprays

IM injections - when the drug passes the needle, it will break down in thickness and produce a DEPOT at the muscle, resulting in sustained release action

nasal spray (ie - nasonex) - SHAKE WELL BEFORE USE. this will allow it to flow more freely to spray. when it thickens in the nasal cavity, it wont leak out and is able to stay there longer

52
Q

what is the name of the law involved with the sedimentation of suspended particles

A

STOKES LAW

53
Q

to DELAY sedimentation according to stokes law, what should the particle size be?

A

as small as possible

54
Q

as density of the liquid medium INCREASES, sedimentation rate _____

A

decreases

55
Q

when is the sedimentation rate zero?

A

when the density of the medium is equal to the density of the solid

56
Q

as the viscosity of the dispersion medium decreases, what happens to sedimentation rate?

A

it increases

57
Q

true or false

it is desirable for suspensions to have very rapid sedimentation

A

FALSE

58
Q

true or false

trituration is not necessary for suspensions

A

FALSE - IT IS

we want the particle size to be as small as possible to limit the rate of sedimentation

optional for SOLUTIONS bc it will dissolve either way

59
Q

“particles should be easily redispersed on gentle shaking and regain viscosity SLOWLY”

A

thixotropy

60
Q

throughout long periods of undisturbed standing of suspensions, what should happen to the particle size

A

should remain CONSTANT

61
Q

true or false

it is desirable to have no grittiness in pharmaceutical suspensions

A

TRUE

also why we must triturate

62
Q

it’s important for suspensions to have a balance between ___ and ____

A

stability vs pourability

should pour readily and evenly, but not be too watery

63
Q

_____ suspensions should be sterilizable

A

parenteral/ophthalmic

64
Q

which have longer (higher) shelf lives and WHY - commercial suspensions or compounded suspensions?

A

commercial suspensions because they have a much smaller particle size than compounded suspensions and are thus more stable

65
Q
A

Compounding Exam 2 (9 decks)

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