Emulsions

Question 1

Define micro-emulsion

Answer 1

dispersed globules whose colloid dispersion’s are less than 1microm

Question 2

What are the uses of emulsions?

Answer 2

oral emulsions, IV/IM, external creams and lotions (semi solids)

Question 3

Give an example of an oral emulsion and what is the active ingredient?

Answer 3

Cod liver oil emulsion

The active ingredient is usually oil and so its o/w

Question 4

What are the property differences of o/w compared to w/o?

Answer 4

o/w is less greasy, viscous and quicker absorption than w/o

Question 5

What are properties of the ideal emulsion?

Answer 5

The globules should remain the same size and evenly dispersed. Cracking (where water comes out of the dispersed phase and cant be re-dispersed) and creaming (where oil rises/sinks) should be prevented.

Question 6

What are emulsifying agent used for?

Answer 6

to prevent droplets joining together

Question 7

Give examples of natural emulsifying agents

Answer 7

polysaccharides (acacia, starch, tragacanth), semi synthetic polysaccharides (methylcellulose) and sterols (beeswax, wool fat)

Question 8

Give examples of synthetic surfactants as emulsifying agents

Answer 8

anionic (soaps - SDS), cationic (anti microbial - cetrimide), non ionic (glycerol, polysorbates, emulsifying wax)

Question 9

What does it mean if an emulsifying agent has a low number?

Answer 9

it is an oil soluble agent (w/o)

Question 10

Discuss finely divided solids as emulsifying agents

Answer 10

they form stable emulsions and include bentonite and colloidal silicon dioxide

Question 11

Give the 3 types of emulsifying agents

Answer 11

1. natural
2. synthetic surfactants
3. finely divided solids (powdered)

Question 12

What other excipients are needed in emulsions?

Answer 12

antioxidants, preservatives (chloroform, benzoic acid) and colours and flavour.

Question 13

How can you prevent creaming and cracking?

Answer 13

• retain globule size
• prevent extreme temperatures
• use stabilisers to prevent globules joining
• prevent microbial contamination

Question 14

What are the advantages of internal emulsions?

Answer 14

• makes oils palatable
• easy to swallow
• fast absorption
• enables oils to be given as IV

Question 15

What are the disadvantages of internal emulsions?

Answer 15

• not very stable
• problems with cracking and creaming
• difficult to manufacture
• can be inconvinenit to patient
• must shake before use

Question 16

What are the advantages of external emulsions?

Answer 16

• can have a cooling effect on the skin
• local effect (no systemic side effects)
• can be greasy or non greasy
• can be used to treat a large area
• can be used as soaps

Question 17

What are the disadvantages of external emulsions?

Answer 17

• stability problems
• difficult to apply
• must shake the bottle
• bath additives can cause slips
• paraffin can be flammable
• preservatives can irritate the skin

Question 18

What are collodions?

Answer 18

They form a waterproof film on the skin e.g. bazuka

Question 19

What are the excipients needed in collodions?

Answer 19

solvents, proxylin, camphor (waterproof excipient), plasticiser (makes the film flexible)