Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharmacotherapy > Emulsions > Flashcards

Emulsions Flashcards

1
Q

What is the definition of an Emulsion?

A

A dispersed system that contains at least two immiscible liquids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the average range of the droplet size in an emulsion?

A

0.1 to 100uM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is O/W emulsions?

A

An emulsion in which the oil is dispersed as droplet throughout the aqueous phase (>45%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a W/O emulsions?

A

An emulsion in which water is the dispersed phase and an oil is the continuous phase. Water is less then 45% of the total weight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Advantages of emulsions as dosage forms?

A

Dissolving the drug in the oil or polarizing the drug protects it from

Emulsions are in a state that can be absorbed

Emulsion can mask the taste of the ingredients and are easier for patients to swallow/use

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the most common choice of emulsion type for Oral administration?

A

O/W emulsions to ensure a pleasant taste

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the advantages of emulsions as a dosage form?

A

Dissolving the drug in the oil or polarizing the drug protects it from

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What type of state of emulsions in?

A

In a state that can be absorbed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What do emulsions mask?

A

Poor drug taste

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the fixed oils we should recgonize?

A

Castor Oil, Cod liver oil, Olive oil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is Fixed oil?

A

Non-volatile fatty oil of animal or plant derivation a mixture of esters of fatty acids, usually triglycerides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are essential or volatile oils?

A

non fatty oils from plants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are mineral oil?

A

A grade of liquid petrolatum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the mineral oil we should remember?

A

Liquid Paraffin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the water phases we should remember

A

Water, Glycerol, Propylene Glycol
Polyethylene glycols

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is an emulsion?

A

Oil, water, emulsifier, energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the purpose of an emulsifying agents?

A

They work to reduce the interfacial tension
Imparting a charge on the droplet, electrostatic repulson

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the requirements for emulsifying agents?

A

Molecular structure
Stable interface
Chemical stability
Inertness
Non-toxic, non irritating
Odorless, tasteless, colorless
Non cost prohibit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the classifications of emulsifying agents?

A

Based on chemical structure or
Based on mechanism of action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

With respect to emulsifying agents mechanism of action what are the three different categories?

A

Surface active agents
Hydrophillic colloids
Finely divided solid particles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

With respect to emulsifying chemical structure what are the four different categories?

A

Synthetic and semi synthetic
Natural
Finely dispersed solids
auxiliary agents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the classifications of emulsifying agents?

A

Water soluble
Anionic soaps
Cationic surfactants
Finely divided solids
Natural non-ionic
Synthetic non-ionic surfactants
Zwitterionic emulsifiers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are Naturally derived emulsifying agents

A

Plant derivatives
Animal Derivatives

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the semi-synthetic structure?

A

Cellulose derivatives that are mainly water soluble polymers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the synthetic surfactant anionic properties?

A

Hydrophobic tail region with a negative charge hydrophilic head

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What products are anionic surfactants?

A

Sulfated and sulfonated compounds (o/w emulsions) such as sodium lauryl sulfate

Calcium oleate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are anionic surfactants generally used for?

A

Topical detergents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are the issues with anionic surfactants?

A

Can be toxic and cannot be used on broken skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are cationic surfactants?

A

Polar head group is positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What compounds encompass a cationic surfactant?

A

Benzylkonium chloride

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are non ionic surfactants?

A

These are hydrophobic tail and hydrophillic head group.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What are the non-ionic surfactants we should know?

A

Sorbitan esters (Spans) and Polyxyethylene sorbitan (Tweens)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What are Tweens

A

Polyoxyethylene Sorbitan Esters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are Spans?

A

Sorbitan Esters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What are the general properties of Tweens?

A

More hydrophilic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What are the properties of Spans?

A

More Hydrophobic (As comparred to tweens)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What are amphoteric Surfactants?

A

Carry both a positive a negative charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

If the hydrophobic protion predominates in the non-ionic surfactants?

A

Surfactant is oil soluble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

If the hydrophilic portion predomoninates in the ionic surfactants?

A

The surfactant is water soluble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What are finely divided solids?

A

Form a particulate layer around the dispersed droplets

41
Q

What do finely divided solids do?

A

Increase inter-particulate distance and minimize inter particle interaction

42
Q

What determines viscosity?

A

Depends on the internal concentration (Relative to the volume of the internal phase0

43
Q

What are auxillary emulsifiers?

A

These are not generally used separetley. but used in combination with other emulsifying agents.

They stabilize the system by thickening . Retard inter particle movement

44
Q

Non-ionic emulsifiers are?

A

Less toxic, Less irritant

45
Q

What is the issue with cationic emulsifiers?

A

Toxic at low concentration hence limited to external use when antiseptic properties are required

46
Q

What is the issue with anionic emulsifiers?

A

They have a high pH and hence are not suitable for broken skin

47
Q

How are emulsifying agents classified?

A

according to the type of interfacial film formed

48
Q

What is the mono-molecular film?

A

Allows the layers to combine/come together

Surface active agent

49
Q

What is multi-molecular film

A

Causes no change in interfacial tension and protects

Hydrocolloids

50
Q

Solid particle film

A

Forms particulate layer, swells, increase, viscosity.

Stops droplet movement

Finely divided solids

51
Q

What do my hydrophilic emulsifiers form?

A

Form O/W emulsions

52
Q

What do my lipophilic emulsifiers form?

A

Form W/O emulsions

53
Q

What is the HLB system?

A

It refers to the relative polarity

54
Q

What is a low HLB number indicate?

A

0-10 low polarity lipophillic surfactant

55
Q

What is a high HLB numbers (10-20) High polarity

A

Hydrophilic surfactant

56
Q

What is an HLB value of 8-16 mean?

A

Emulsifying agent for O/W emulsions, water soluble

57
Q

What is an HLB value of 3-8 mean?

A

Oil soluble

58
Q

What are common surfactants?

A

Spans and Tweens

59
Q

What is the HLB value of SPANS

A

1.8 to 8.6

60
Q

What is the HLB value of Tweens

A

10.5-16.7

61
Q

What is the desired HLB value for a W/O emulsion?

A

3-8 to impart lipophilicity

62
Q

What is the desired HLB value for a O/W emulsion?

A

8-16 to impart hydrophilicity

63
Q

What is the formula for calculating the HLB mixture?

A
64
Q

How do we calculate the tween value or span value?

A
65
Q

What are antioxidants?

A

Use to prevent auto-oxidation oil and lipid components of the emulsion

66
Q

What are the examples of antioxidants?

A

BHA BHT

67
Q

What are preservatives used for?

A

use to prevent growth of microorganisms.

68
Q

What are preservatives made up of?

A

Lipid and water soluble preservatives are combined

69
Q

What is the issue with usage of preservatives?

A

Often they can inactivate the emulsion mixtures

70
Q

What are humectants?

A

Humectants are compounds capable of absorbing water from the air

71
Q

What are humectants used for?

A

Reduce evaproation of the water phase of an emulsion (to prevent drying of the preparation)

72
Q

What is flocculation?

A

A process by which a chemical coagulant added to the water acts to facilitate bonding between partciles. Creating larger aggregates which are easier to separate

73
Q

Most important requirement of a well fomrulated meulsion?

A

It possess adequate physical stability

74
Q

A stable emulsion is?

A

on in which the dispersed droplets retain their original characteristics and remain uniformly distributed throughout the continuous phase

75
Q

What are the three phenomena associated with physical instability of emulsions?

A

Creaming or sedimnetaiton
Flocculation Coagulation
Coalescence (Solidfying)

76
Q

Disperse droplets in an emulsion may move either upward ____, or downward ______ within the continuous phase

A

Creaming, sedimentation

77
Q

The direction of mvoement is determiend by the density of the

A

droplets relative to the density of the continuous pahse

78
Q

What does stokes law define?

A

Frictional and drag force exerted on spherical particles in a viscous fluid

79
Q

What is the secondary minimum mean?

A

This is where the easy dispersion is

80
Q

What is the primary maximum?

A

Where repulsion is greater than attraction and particles are going to avoid (Most ideal state of dispersion)

81
Q

The primary minimum indicates?

A

The lowest energy condition and this is where we could expect the particle to reside

82
Q

What is the issue with the primary minimum?

A

More serious and redispersion is VERY difficult

83
Q

What is our ideal dispersion phase?

A

Primary maximum

84
Q

What is coalescence?

A

Fusion of droplets into 1 mass

85
Q

What is resistance

A

In O/W emulsion is provided by strength of mono- or multimolecular film

While coalescence in w/o emulsions is prevented by presence of long hydrocarbon chains of surfactant molcules which project into the oil phase

86
Q

What do you do in excessive foaming?

A

Reduce surfactant concentration, avoid air incorporation

87
Q

Mechanical stirrers (rotating blades)

A

❑ used for low viscosity preparations
❑ large quantities may be mixed

88
Q

Homogenizers

A

❑ small inlet orifice and pressure is used to incorporate oil
❑ limitation → not suitable for viscosity > 2000 cP

89
Q

Ultrasonifiers

A

❑ use ultrasonic waves to break down emulsified droplets
❑ produces a uniform emulsion
❑ gentle → powerful

90
Q

Colloid Mills (rotor/stator)

A

❑ frequently used

91
Q

The most important requirement of a well-formulated emulsion is that it

A

possess adequate physical stability

92
Q

There are three primary phenomena associated with physical instability of emulsions

A
  1. Creaming or Sedimentation
  2. Flocculation
  3. Coalescence (breaking, cracking)
93
Q

Dispersed droplets in an emulsion may move either upward (___) or downward (___) within the continuous phase

A

Creaming, Sedimentation

94
Q

What is Stokes law tell us?

A

Defines the frictional force or drag force exerted on spherical particles in a viscous fluid

95
Q

the rate of creaming/sedimentation will be reduced by

A

Decreases droplet size (homogenization)

Decreases in the density difference between the two phases (not
used in practice)

Increased viscosity of the continuous phase (e.g. with hydrocolloids)

control of the disperse phase concentration (≈ 20 - 60%)

96
Q

Is Coalescence reversible?

A

NoI

97
Q

Is creaming reversible?

A

Yes

98
Q
A

Pharmacotherapy (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions