Internal and external emulsions Flashcards

1
Q

Are oral emulsions o/w or w/o

A

Always o/w

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2
Q

Which is more greasy and more viscous, o/w emulsions or w/o?

A

w/o

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3
Q

In an ideal emulsion, globules of the dispersed phase retain their size and remain evenly dispersed. True or false?

A

True

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4
Q

Is cracking reversible?

A

No

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5
Q

Is creaming reversible?

A

Yes by shaking

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6
Q

What do emulsifying agents do?

A

Prevent droplets from coalescing

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7
Q

What are the three types of emulsifying agent?

A

Natural
Synthetic surfactants
Finely divided solids

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8
Q

Natural emulsifying agents are more stable than other. True or false?

A

False

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9
Q

Which type of emulsions are polysaccharides used in?

A

o/w internal emulsions

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10
Q

What type of emulsions are sterols used in?

A

w/o

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11
Q

What type of emulsions are semi-synthetic polysaccharides used in?

A

o/w

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12
Q

Non-ionic surfactants are used in all types of emulsions. True or false?

A

True

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13
Q

If an emulsifying agent has a high HLB, which type of emulsion is it suitable for?

A

o/w

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14
Q

If an emulsifying agent has a low HLB, which type of emulsion is it suitable for?

A

w/o

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15
Q

What is the choice of type of emulsifying agent dependent on?

A

The type of emulsion
The route of administration
Active ingredient

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16
Q

Oils are liable to oxidation. True or false?

A

True

17
Q

What are antioxidants used for in emulsions?

A

To prevent oxidation of oils - they are added to the oil phase

18
Q

Why are preservatives needed in emulsions?

A

Needed to prevent microbial growth in water phase as microbes may feed on emulsifying agent

19
Q

Colours and flavours are not needed in emulsions. True or false?

A

False

20
Q

What are the advantages of internal emulsions?

A

Makes oils palatable for oral use
Easy to swallow
Fast absorption from GIT
Enables oils to be given IV

21
Q

What are the disadvantages of internal emulsions?

A
Not very stable
Problems with cracking and creaming
Difficult to manufacture
Can be inconvenient for the patient
Must shake before use
Compliance with storage is important
22
Q

What are the advantages of external emulsions?

A
Can have a cooling effect on the skin
Local effect
No systemic side effects
Good for hairy areas
Can often be used as soaps
23
Q

What are the disadvantages of external suspensions?

A

Stability problems
Difficult to apply
Paraffin can be flammable
Preservatives can irritate the skin

24
Q

What do colloidons do?

A

Form a waterproof film on the skin

25
Q

When making emulsions extemporaneously, always make the primary emulsion with all the oil to ensure stability and then dilute with continuous phase to volume required. True or false?

A

True