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829 Dosage > Emulsion > Flashcards

Emulsion Flashcards

1
Q

definition

emulsion

A

a system of 2 immiscible liquids in which one is dispersed as droplets
* dispersed phase = droplets
* continuous phase = base

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2
Q

Applications of Emulsion

Oral
* ___ to mask the taste of an oil
* O/W to enhance ___ of an oil (Vit A and D, fish oil)

A
  • O/W
  • adsorption
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3
Q

Applications of Emulsion

External
* ___: water-washable; vanishing cream
* ___: for cleansing skin; cold cream

A
  • O/W
  • W/O
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4
Q

Applications of Emulsion

Intravenous lipid emulsion (___)
* for parenteral ____
* 100 mL of 20% lipid emulsion provides ___ kcal, while 100 mL of 5% dextrose only provides ___ kcal.
* smallest capillaries are 5 mcm. It is critical that droplet size is less than ___ mcm to avoid embolisms

A
  • O/W
  • nutrition
  • 200 kcal, 20 kcal
  • 1 mcm
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5
Q

Interfacial phenomena

  • In the bulk portion of each phase, molecules are attracted
    to each other ___ in all directions.
  • At the boundary between phases, molecules are acted
    upon ____ because they are in contact with other molecules exhibiting different forces of ___.
  • water: H bond, mineral oil: ___
  • molecules situated at the interface experience different than the ones in the bulk phase
A
  • equally
  • unequally, attraction
  • london dispersion forces
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6
Q

Interfacial phenomena

In liquid systems such ___ leads to ___ movement of molecules from the interface into the bulk phase. This leaves ___ molecules per unit area at the interface

A
  • imbalance
  • spontaneous
  • fewer
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7
Q

Interfacial tension or surface tension

When you try to reverse the spontaneous movement of molecules at the interface (by ___ the area of contact between phase) the interface resists expansion and behaves as though it is under a ___ everywhere in a tangential direction.

A
  • increasing
  • tension
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8
Q

definition

interfacial tension

A

the force of tension per unit length of interface
* liquid-liquid interface
* example: oleic acid-water = 15.6 dynes/cm

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9
Q

definition

surface tension

A
  • liquid-air interface
  • example: water-air=72.8 dynes/cm, oleic acid-air=32.5 dynes/cm
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10
Q

Interfacial tension or surface tension

The stronger the intermolecular force in a bulk phase, the ___ the
interfacial tension.

A

higher

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11
Q

Interfacial tension or surface tension

the greater the tendency to interact, the ___ the interfacial tension

A

less

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12
Q

Interfacial tension or surface tension

the higher the temperature, the __ interfacial tension

A

lower

intermolecular forces are reduced at high temp

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13
Q

emulsifying agents (emulsifiers)

types of emulsifying agents

A
  • surface active agents (surfactants)
  • hydrophilic colloids (polymers)
  • finely divided solid particles
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14
Q

T or F: emulsifying agents are added to stabilize the emulsion

A

True

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15
Q

What type of emulsifier is this?

A

surfactant

amphiphilic (interacts with both water and oil), think soap

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16
Q

What type of emulsifier is this?

A

hydrophilic colloid

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17
Q

What type of emulsifier is this?

A

fine particles

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18
Q

Surface active agents (Surfactants)

  • molecules that contain both a ___ and ___ region
  • orient at the liquid-liquid or liquid-air interface and ___ interfacial or surface tension
A
  • hydrophilic and hydrophobic
  • lower
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19
Q

Classification of surfactants

What type of surfactant is this?

A

anionic - alkyl sulfate

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20
Q

Classification of surfactants

What type of surfactant is this?

A

cationic - alkyltrimethylammonium bromide

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21
Q

Classification of surfactants

What type of surfactant is this?

A

zwitterionic - alkyl betaine

neutral net charge

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22
Q

Classification of surfactants

What type of surfactant is this?

A

non-ionic - alcohol ethoxylate

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23
Q

Hydrophile-lipophile balance (HLB)

  • low HLBs indicate ___ lipid solubility
  • ranges 0-20 for ____ surfactants
  • calculated according to an empirical formula (picture)
  • in practice, a mixture of emulsifying agents are used to get a desired HLB
A
  • greater
  • non-ionic
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24
Q

definition

hydrophile-lipophile balance (HLB)

A

A measure of the relative contributions of the hydrophilic and lipophilic regions of a surfactant.

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25
Q

Definition

Rule of Bancroft (1913)

A

A relative solubility of the surfactant
determines the type of emulsion (The phase in which a surfactant is more soluble becomes the continuous phase).

26
Q

Hydrophile-lipophile balance (HLB)

Rule of Bancroft (1913) example - , A surfactant with a high HLB (>10, soluble in water) forms an ___ emulsion

A

O/W

more soluble in H2O, so water is the continuous phase

27
Q

HLB calculation

1 L of O/W emulsion contains 3g of Span 80 (HLB 4) and 7g of Tween 80 (HLB 15). What is the HLB value
of the emulsion product?

A

11.7

28
Q

Micelles

As the concentration of a
surfactant increases above the ___ (CMC), the surfactant molecules self-associate into small aggregates called ____

A
  • critical micelle concentration
  • micelle
29
Q

T or F: The outside of the micelle represents a lipid-like region that is capable of dissolving water-insoluble drugs.

A

False; center (not outside)

30
Q

hydrophilic colloids

  • hydrophilic polymers
  • used in ___ emulsions
  • form a multimolecular film at the interface and ___ the viscosity of water
  • do not ___ the interfacial tension
  • examples: acacia, tragacanth, ___
A
  • O/W
  • increase
  • lower
  • gelatin
31
Q

finely divided solid particles

  • particles less than a ___ can adsorb at the interface and form a film of fine particles

Examples:
* Bentonite, magnesium aluminum silicate, aluminum hydroxide: hydrophilic, ___
* charcoal: hydrophobic, ___

A
  • micron
  • O/W
  • W/O
32
Q

Predicting type of Emulsion

T or F: The phase in which the emulsifier is most soluble will be
the external (=continuous) phase.

A

True

33
Q

Predicting type of Emulsion

  • HLB < 10: ___
  • HLB > 10: ___
A
  • W/O
  • O/W
34
Q

Predicting type of Emulsion

T or F: hydrophilic colloids are W/O only

A

False; O/W

35
Q

Predicting type of Emulsion

finely divided solids
* hydrophilic if contact angle __ 90º: O/W
* hydrophobic if contact angle __ 90º: W/O

A
  • < (less than)
  • > (greater than)
36
Q

definition

Phase volume ratio

A

volume of oil phase/total volume of the emulsion

37
Q

Predicting type of Emulsion

Phase volume ratio ranges
* 0-___%: O/W only
* 26-___%: O/W or W/O
* 74-___%: W/O only

A
  • 26%
  • 74%
  • 100%
38
Q

definition

Creaming is…

A

Reversible as long as the interfacial film is effective in maintaining the integrity of individual droplets

can be overcome by shaking

39
Q

Instability of Emulsion

Creaming (Stokes Law)
What does V stand for?

A

velocity of sedimentation

how fast it sinks

40
Q

definition

Coalescence

A

Droplet size increases because the interfacial film is unable to maintain the integrity of individual droplets.

41
Q

Instability of Emulsion

Coalescence
* ____ and will ultimately lead to a layer of oil and layer of water
* must be reformulated

A

irreversible

42
Q

T or F: Coalescence can be fixed by shaking the bottle

A

False; cannot be fixed by shaking, must be reformulated

43
Q

Instability of Emulsion

Phase inversion
* Due to Phase volume ratio exceeding ___%
* O/W emulsion stabilized with sodium stearate can be inverted to W/O type using hard water (containing ___)

A
  • 74%
  • Ca2+
44
Q

Instability of Emulsion

T or F: rule of thumb: keep phase volume ratio < 50% to avoid inversion

A

True

45
Q

Preparation of an Emulsion

Emulsion preparation steps:
1. Dissolve all water-soluble ingredients in ___.
2. Mix all oil-soluble ingredients in ___. Heat if necessary to melt.
3. Heat the ___ solution to the same temperature as ___ solution.
4. Mix oil solution + water solution with mixing
5. Cool slowly.
6. Pass through a ___ or ___

A
  • water
  • oil
  • aqueous, oil
  • colloid mill or homogenizer
46
Q

Keri Silky Lotion

Benzyl alcohol is a …

A

preservative

47
Q

Keri Silky Lotion

Cetyl alcohol is a …

A

emulsifier, thickening agent

48
Q

Keri Silky Lotion

Glycerin is a…

A

humectant (active ingredient for moisturizer)

49
Q

Keri Silky Lotion

liquid petrolatum is a…

A

oil phase

50
Q

Keri Silky Lotion

magnesium aluminum silicate is a…

A

emulsifier

51
Q

Keri Silky Lotion

Water is a…

A

aqueous phase

52
Q

ArthriCare Medicated Rub

Capsicum and menthol are…

A

active ingredients

53
Q

ArthriCare Medicated Rub

Cetyl alcohol

A

emulsifier and thickening agent

54
Q

ArthriCare Medicated Rub

glycerin is a…

A

humectant

55
Q

ArthriCare Medicated Rub

mineral oil is…

A

oil phase

56
Q

ArthriCare Medicated Rub

polysorbate 60 is a…

A

emulsifier

57
Q

ArthriCare Medicated Rub

propylene glycol is a…

A

humectant

58
Q

ArthriCare Medicated Rub

sodium lauryl sulfate is a…

A

emulsifier

59
Q

ArthriCare Medicated Rub

stearyl alcohol is a…

A

emulsifier and thickening agent

60
Q

What is this molecule?

A

Polysorbate 60 - emulsifier: non-ionic surfactant

829 Dosage (4 decks)

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