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PHAR 224 - Formulations (2) > Emulsions > Flashcards

Emulsions Flashcards

Idonotlikethisbullshit

1
Q

What is an emulsion?

A

A dispersed system with at least 2 immiscible liquids. One is always aqueous and one is always oleaginous.

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2
Q

What is the internal phase?

A

The liquid that is finely subdivided into droplets and is dispersed through the external phase.

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3
Q

What is O/W emulsions and what properties do they have?

A

Oil in water
Water is >45%= external phase
non greasy, water washable

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4
Q

What is W/O emulsions and what properties do they have?

A

Water in oil
water is <45%= internal phase
greasy, occlusive, forms water repellant film

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5
Q

What are the two types of multiple emulsions?

A

W/O/W= water droplets in larger oil droplets dispersed in water
O/W/O= oil droplets in larger water droplets dispersed in oil

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6
Q

Pros of emulsions compared to other dosage forms?

A

-Easier to eat/ taste
- bypass dissolution= faster
- combine 2 incompatible ingredients
- better for parental administration if lipid component is necessary.

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7
Q

Which emulsion is used for oral?

A

O/W= because better taste

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8
Q

Which emulsion for IV?

A

O/W= because serious embolism if W/O is used

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9
Q

Which emulsion for IM?

A

W/O= because of sustained release (depot effect)

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10
Q

What oils do we choose for oral emulsions

A

castor oil, cod liver oil, olive oil, liquid paraffin (mineral oil)

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11
Q

What oils for IV emulsions

A

Cotton seed

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12
Q

What oil for topical emulsions?

A

turpentine, benzyl-benzoate, liquid paraffin

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13
Q

What are our choices for water phase?

A

water
glycerol
PEG

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14
Q

What is the mechanism of action for emulsifying agents?

A

Lowers the interface tension making it more miscible
puts charges on droplets

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15
Q

What is part of egg yolk that acts as a emulsifying agent?

A

lecithin

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16
Q

What type of emulsions would lotions, creams, and ointments be?

A

L=o/w
C=both
O= w/o

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17
Q

What are the natural emulsifying agents?

A

Plant= tragacanth, xanthin gum= o/w
Animal= gelatin, lanolin= w/o

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18
Q

What are some semi synthetic emulsifying agents?

A

MC
CMC

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19
Q

What are anionic surfactants?

A

have a negative changed head
Soft and hard soaps

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20
Q

What are soft soaps and give examples?

A

alkali metal and ammonium soaps
ie) sodium,K, NH3 stearate

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21
Q

What are hard soaps and give examples

A

Divalent or trivalent metals
Ie) calcium oleate

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22
Q

What is special about soft soaps?

A

can be formed in situ

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23
Q

What emulsions do soft soaps make

A

o/w

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24
Q

What emulsions do hard soaps make?

A

w/o emulsions

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25
Q

What emulsions do detergents make?

A

o/w

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26
Q

What is a detergent agent?

A

sodium lauryl sulfate

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27
Q

Of the three anionic surfactants (soft, hard soaps, detergent) which is most common and why?

A

detergent because resistant to hydrolysis

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28
Q

What are cationic surfactants and give examples?

A

Have a positive charged head.
Ie) quaternary ammonium compounds like benzylkonium chloride and benethonium chloride

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29
Q

What is special about cationic surfactants?

A

can be used as preservative in ophthalmic formations

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30
Q

What are non-ionic surfactants and give examples?

A

have a hydrophilic head no charge.
ie) usually an alcohol, or fatty acid has moiety

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31
Q

Of all surfactants which is most common and why?

A

non-ionic due to neutral at pH and resistant to acids and electrolytes

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32
Q

If hydrophobic portion of non-ionic surfactant which phase is it soluble in?

A

oil phase

33
Q

Of span and tween which is hydrophobic and which is hydrophilic

A

tween= hydrophilic
span= hydrophobic

34
Q

What is a zwitterionic surfactant?

A

carries both cationic and anionic charge.

35
Q

What are finely divided solids?

A

form a particulate layer around droplets to increase inter particle distances.

36
Q

What emulsions are formed from finely divided solids?

A

o/w emulsions but bentonite can also form w/o

37
Q

Examples of finely divided solids?

A

bentonite, veegum

38
Q

What are auxiliary emulsifiers?

A

are weak and need another one as well.
They act by thickening

39
Q

Examples of aux emulsifiers?

A

stearic acid, cetyl alcohol

40
Q

When should we NOT use ionic emulsifiers and why?

A

NO for oral due to cationic being toxic and bad taste
anionic is basic= NO for broken skin

41
Q

Which surfactants may be used in Parenteral?

A

NON-ionic= lecithin, polysorbate 80

42
Q

What are the three MOA of emulsifying agents?

A

1= Mono film- go to interface and reduces surface tension(surface agents)
2= Multi film- makes protective sheath and gives charge to droplets= repel (hydrocolloids)
3= Solid particle film- layer then swell to increase viscosity (FDS)

43
Q

CMC is a term we learned about, What does it mean and what does a LOW number indicate?

A

CMC= concentration of surfactant where micelles will form micelles
WE WANT a High number because if it is low it will be coated before forming micelles.

44
Q

What does a low HLB indicate

A

lipophilic

45
Q

What does a high HLB indicate?

A

hydrophilic
>10

46
Q

What is the formula for finding HLB of a mixture

A

HLB= y x HLB + (1-y) x HLB

47
Q

If we want a O/w emulsion what HLB are we expecting?

A

> 8

48
Q

WHICH PHASE ALWAYS GETS POURED INTO THE OTHER ONE?

A

water phase into oil phase due to not wanting the oil phase to precipitate out.

49
Q

What are antioxidants we can add?

A

BHA,BHT, Vit e, Vit C

50
Q

What are some preservatives we can add and which phase do they like?

A

Methylparaben= water
propylparaben=oil phase

51
Q

What can happen with the common preservatives and tweens?

A

parabens can bind and inactivate

52
Q

What are humectants and give examples?

A

Absorb water from air= keep moist
ex) PEG, glycerol, sorbitol

53
Q

What is the dry gum method?

A

add gum to oil then add water to oil all at once to get emulsion

54
Q

What is the wet gum method?

A

add water to gum then get mucilage then slow addition to oil phase

55
Q

What type of mortar for natural ingredients?

A

not glass due to high energy to break it down

56
Q

Which method wet or dry is better?

A

no clear answer but wet gum works better for tragacanth

57
Q

What is special about lime water and cottonseed oil?

A

form in situ calcium oleate = hard soap= w/o emulsion

58
Q

What ways can we mix emulsions?

A

Mechanical stirrers= for low viscosity
Homogenizers= no for high viscosity
Ultrasonifiers= gentle and powerful
Colloid mills= when need scaling up production

59
Q

What aux labels always?

A

for external use and shake well

60
Q

What three things can happen if the stability of emulsion is super low?

A

cream/ sediment
flocculate
coalescence

61
Q

Which way do particles move if creaming is happening

A

up

61
Q

Which way do particles move if sedimentation is happening

A

down

62
Q

How can we predict whether creaming or sedimentation may happen?

A

density of droplets and density of continuous phase

63
Q

How can we reduce creaming/sedimentation?

A

lower droplet size
increase viscosity of continuous phase

64
Q

Is creaming or sedimentation reversible

A

Yes

65
Q

In stokes law what does a negative value indicate?

A

creaming

66
Q

What is stokes law?

A

V=d^2(Pint-Pext)/(18xnext) x g

67
Q

What does primary minimum mean?

A

very attractive potential

68
Q

What does primary maximum mean?

A

repulsion is greater= ideal for dispersion

69
Q

What does secondary minimum mean?

A

shallow attraction for easy dispersion

70
Q

Which is okay Primary max/min or secondary minimum

A

Primary min= NO hard to disperse
Primary max= IDEAL
Secondary min= not bad. just need to shake

71
Q

What is coalescence?

A

fusion of droplets which can eventually lead to separation

72
Q

How can we stop coalescence?

A

o/w= strength of mono films
w/o= need long hydrocarbon chains of surfactants into oil phase

73
Q

What does flocculation mean?

A

aggregate

74
Q

Can coalescence be fixed?

A

NOOOOOOO

75
Q

What to do if it foams?

A

lower surfactant and mix slower

76
Q

What is BUD if water containing?

A

14 days

76
Q

What is BUD for external preps?

A

1 month

PHAR 224 - Formulations (2) (6 decks)

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