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Pharmaceutics > Emulsion > Flashcards

Emulsion Flashcards

1
Q

What is an emulsion?

A

Dispersion of two immiscible or partially miscible liquids where one is uniformly distributed as fine droplets within the other; both must be relatively stable + homogeneous

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2
Q

When are multiple phase emulsions used?

A

Often as modified/slow release dosage forms

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3
Q

What is generally needed as a third phase in multiple phase emulsions?

A

An emulsifying agent; required to stabilize emulsions

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4
Q

How are emulsions administered?

A

Oral
Topical
Parenteral

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5
Q

Oil in water emulsions mask what?

A

Foul tasting oils

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6
Q

How would you make the oil more digestible and readily absorbed?

A

Globule size reduction

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7
Q

What does a globule size reduction do to the oils?

A

Makes them more digestible and readily absorbed

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8
Q

What kind of emulsion is more easily removed by water?

A

Oil in water

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9
Q

What kind of emulsion can be applied more evenly?

A

Water in oil

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10
Q

(T/F) Advantages of Emulsion

Poorly water soluble drugs may be easily incorporated

A

True

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11
Q

(T/F) Advantages of Emulsion

Does not do much to mask unpleasant taste/odor of oils

A

False; it does mask

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12
Q

(T/F) Advantages of Emulsion

Enhanced abosorption

A

True

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13
Q

What is the surface tension theory?

A

Assumes a shape to minimize their surface area

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14
Q

According to the surface tension theory, when two or more drops of the same liquid come into contact, what is thermodynamically favorable?

A

To coalesce, form one large drop to reduce surface area

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15
Q

According to the surface tension theory, what do surfacants, emulsifiers, or wetting agents do?

A

Encourage liquids to disperse into smaller drops

Lowers interfacial tension of two immiscible liquids + reduce repellent force while lowering liquids attraction for its own molecules

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16
Q

According to the surface tension theory, by _______ interfacial tension, surfactants, emulsifiers help convert large globules into smaller ones that have a _____ tendency to reunite/coalesce

A

lowering

lower

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17
Q

What is the oriented wedge theory?

A

Surfactant/emulsifying agents form monolayers around droplets of the internal phase of the emulsion to prevent coalescence

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18
Q

What is the plastic or interfacial film theory?

A

Emulsifier forms an interface between the oil and water

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19
Q

According to the oriented wedge theory, a wedge encompasses the globules preventing _____

A

coalescence

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20
Q

According to the plastic or interfacial film theory, what prevents the contact and coalescing of the dispersed phase?

A

film

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21
Q

According to the plastic or interfacial theory, what must the film be able to do to each drop?

A

Coat the entire surface

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22
Q

According to the plastic or interfacial theory, water-soluble agents encourage what kind of emulsions?

A

Oil in water

Vice versa for the other way around

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23
Q

In reality, what is the caveat behind all three theories?

A

None individually explain the mechanism by which emulsifiers form and stabilize emulsions

24
Q

It is very likely that these theories simultaneously play a part (T/F)

A

True

25
Q

When picking an emulsifier, what should it be?

A
  1. Stable
  2. Non-toxic
  3. Little to no odor, taste or color
  4. Proper HLB balance
26
Q

Carbohydrates form what emulsions?

A

Oil in water

27
Q

What are examples of carbohydrate emulsifying agents?

A

Acacia

28
Q

Proteins form what emulsions?

A

Oil in water

29
Q

What are examples of protein emulsifying agents?

A

Gelatin

30
Q

High molecular weight alcohol form what emulsions?

A

Oil in water

31
Q

Cholesterol forms what kind of emulsion?

A

Water in oil

32
Q

Surfactants + wetting agents may be:

  • Non-ionic
  • Ionic
  • Anionic
  • Cationic
  • Zwitterionic
A

All except ionic

33
Q

Surfactants + wetting agents form what emulsions

A

Both kinds

34
Q

Emulsions are considered physically unstable if:

A
  1. Globules tend to form upon standing
  2. Large globules rise/sink to form a concentrated layer
  3. Ostwald ripening
35
Q

Large globules rise/sink to form a concentrated layer is known as….

A

creaming

36
Q

Is creaming reversible?

A

Yes

37
Q

How can you reduce creaming?

A
  1. Form smaller particles
  2. Increase viscosity
  3. Decrease density difference
38
Q

What is Ostwald ripening?

A

Diffusion of material from smaller to larger droplets in the continuous phase

39
Q

When is Ostwald ripening most often observed in?

A

water in oil

40
Q

Which temperature should you protect emulsions from?

A

Extreme cold + heat

41
Q

What does freezing/heating do to emulsions?

A

Separation and coalescence of the internal phase

42
Q

When is temperature a issue in emulsions?

A

Shipping/storage, time of year, different countries

43
Q

How can small-scale emulsions prepared by?

A
  1. Mortar/pestle
  2. Blender
  3. Simple prescription bottle
44
Q

What are the two small-scale emulsion methods?

A
  1. Dry gum method

2. Wet gum method

45
Q

Dry gum method is referred to as the ________ method

A

4:2:1

4 x oil, 2 x water, and 1 x emulsifying agent

46
Q

What is the usual emulsifying agent for the dry gum method?

A

Acacia gum

47
Q

How is the wet gum method different from the dry gum counterpart?

A

Order is different

After the viscous paste is made, it is followed by a slow addition of the oil

48
Q

Higher HLB numbers means the more _______ the surfactant/emulsifying agent

A

hydrophilic

49
Q

HLB values are ______ additive

A

algebraically

50
Q

What is trituration?

A

Process of grinding to a fine powder in the dry state

51
Q

What is Levigation?

A

Process of grinding an insoluble substance to a fine powder while wet

52
Q

What is the levigating agent?

A

Liquid that is used to grind the insoluble material

53
Q

While levigation is happening, powder being ground must not be ____ in the liquid

A

soluble

54
Q

HLB values of 3-6 are greatyl _______ and produce ______ emulsions

A

Lipophilic

water in oil

55
Q

HLB values of 8-18 are greatly _______ and produce ______ emulsions

A

hydrophilic

oil in water

Pharmaceutics (30 decks)

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