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PHARM 124 - Emulsions Exam Questions And 100% Correct Answers
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PHARM 124 - Emulsions Exam Questions And100% Correct Answers
What is an emulsion?
- An emulsion is defined as a dispersed system containing at least two immiscible liquids
- One of the liquids (internal phase) is finely subdivided and uniformly distributed as
droplets throughout the other (external phase)
- One aqueous (water) one oleaginous (oil)
emulsion droplet size
Droplet sizes range from 0.1 - 100 μm
Two types of emulsions
oil-in water (O/W) and water-in oil (W/O)
Oil-in-Water (O/W) Emulsions:
Oil droplets dispersed in a water with the aid of an emulsifying agent.
Water-in-Oil (W/O) Emulsions:
an emulsion where water is the dispersed phase and an oil is the continuous phase
(dispersion medium)
,multiple emulsions
Disperse phase contains droplets of another phase; W/O/W; O/W/O
its an emulsion within an emulsion... emul-ception :-)
What is the purpose of multiple emulsions?
• Developed to produce a sustained release of the active ingredient.
• Any drug present in the innermost phase must cross two phase boundaries to reach
the external or continuous phase (to be available for absorption).
W/O/W Emulsions
• consist of small water droplets which are enclosed in a large oil droplet,
which in turn is dispersed in water
O/W/O Emulsions
• small oil droplets are enclosed in a large water droplet, which is dispersed in oil
Describe microemulsions and their size
The dispersed globules are of colloidal dimensions (1 nm - 1 μm)
the preparation is frequently transparent
, Describe nanoemulsions and their size
The dispersed globules are of colloidal (nano) dimensions (<200 nm)
the preparation is transparent
What would be required to stabilize emulsion systems
surfactants!
Which 3 tests could be used to identify emulsion type
Dilution test
Conductivity test
Dye-solubility test
Dilution test
This test relies on the fact that o/w emulsions can be diluted with water and w/o
emulsions can be diluted with oil (i.e. dilution can occur with the external phase only).
SOO... if the diluent you use is miscible you will know what the external phase is that
Conductivity Test
The conductivity of an emulsion that has water as the continuous phase will be a much
more efficient conductor of electricity than will an emulsion with an oil as the continuous
phase.
- O/W will conduct heat and energy (because water conducts) and W/O won't
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