internal and external emulsions

Question 1

what is the size of a microemulsion?

Answer 1

less than 1 micrometer

Question 2

what will the type of emulsion depend on?

Answer 2

properties of the drug and the use of the product

Question 3

uses of injections:

Answer 3

oral emulsions, IV/IM injections, total parenteral nutrition, creams / lotions

Question 4

Factors to consider

Answer 4

Choice of emulsion - o/ or w/o
choice of oil phase - internal vs external
conc of the dispersed phase - maximum 60%
particle size of the dispersed phase
viscosity vs density of the continous phase

Question 5

what type of emulsion is an oral emulsion?

Answer 5

oil in water. active ingredient is oil

Question 6

features of an oil in water emulsion

Answer 6

less greasy, can be less viscousm rapid absorption/evaporation on the skin. E.g. Derbac M

Question 7

Features of a water in oil emulsions

Answer 7

greasy by nature, more viscous and occlusive, most commonly use liquid paraffin

Question 8

What are the features of an ideal emulsion?

Answer 8

Globule of the dispersed phase retain their initial character, stay the same size and remains evenly dispersed

Question 9

problems with emulsion?

Answer 9

Cracking: water come out of the dispersed phase and cannot be redispersed.
creaming; oil rises to top or sinks to the bottom in an o/w emulsion, shaking can redisperse

Question 10

why are oil in water emulsions given instead of just oil?

Answer 10

to make it more platable

Question 11

what do emulsifying agents do?

Answer 11

prevent droplets from coalescing

Question 12

what are the 3 types of emulsifying agents?

Answer 12

Natural and synthetic emulsifying agents, synthetic, finely divided solids

Question 13

Features of a natural emulsifying agent?

Answer 13

they are less stable than others.

• polysaccharides (internal o/w)
• semi synthetic polysaccharides (o/w)
• sterols (external /o)

Question 14

give examples of a natural emulsifying agent polysaccharides

Answer 14

acacia, starch, pectin, tragacanth

Question 15

give examples of a natural emulsifying agent semi synthetic polysaccharide

Answer 15

methylcellulose

Question 16

give examples of a natural emulsifying agent sterol

Answer 16

beeswax, wool fat

Question 17

what will determine your choice of emulsifying agent?

Answer 17

type of emulsion, route of adminstration and active ingredient

Question 18

what do antioxidants do?

Answer 18

they are added to the oil phase as oils are liable to oxidation

Question 19

what do preservatives do?

Answer 19

they protect the water phase from microbe growth

Question 20

examples of preservatives

Answer 20

benzoic acid, chloroform, cetrimide, chlorocresol

Question 21

excepients in an emulsion?

Answer 21

antioxidants, preservatives, colours and flavours, emulsifying agents

Question 22

How can creaming and cracking be prevented?

Answer 22

Retaining globule size at optimum size
Stopping extremes of temperature
Using stabilisers to prevent coalescence
Preventing microbial contamination

Question 23

what is the usual packagaing for oral / external liquid emulsions?

Answer 23

glass/plastic bottle

Question 24

advantages of internal emulsions?

Answer 24

makes oils palatable for use.
-easy to swallow
-fast absorption from GIT
Enables oils to be given IV
Depot injections can improve compliance

Question 25

disadvantages of internal emulsions?

Answer 25

not stable, can crack and cream, difficult to manufacture, can b inconvenient for patient, must shake before use, storage is important

Question 26

advantages of external emulsions?

Answer 26

cooling effect on skin, local effect, no systemic side effect, can be greasy/non greasy

Question 27

disadvantages of external emulsions

Answer 27

unstable, difficult to pay, must shake bottlem paraffin can be flammable, preservatives can irritate skin

Question 28

what do collodions do?

Answer 28

they form a water proof film on the skin

Question 29

are collodions flammable?

Answer 29

yes, highly

Question 30

how are collodions packaged?

Answer 30

aluminum/plastic tubes or glass bottles

Question 31

what does camphor?

Answer 31

makes the film water proof

Question 32

what is a plasticiser and give an example

Answer 32

makes the film flexible & caster oil

Question 33

what are some of the things you need to check in a final check of an emulsion?

Answer 33

creaming, cracking or phase inversion

• smell - chloroform not dissolved
• correct final volume
• clean bottle with label