PHA 327 - Exam 2 - Emulsions 2
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How do emulsions solve the issue of bad tasting oil based drugs?
They are more palatable in an emulsion
What oil based drugs discussed in class are made more palatable in an emulsion?
- Mineral oil laxatives
- Oil stable vitamins
- High fat nutritive preparations
What drugs are made more bioavailable by emulsions that reduce the oil globule size of the drug?
How can issues with skin irritating drugs be reduced with emulsions?
Skin irritating drugs can be incorporated into an emulsion as the internal phase, where they are less irritating
How are emulsions useful for x-ray examination?
Radio-opaque emulsions are used in diagnostic agents for x-ray exams
Aerosols utilize what type of technology?
How can aqueous drugs be made into intramuscular depots?
If they are made into W/O emulsions
Why are some liquids immiscible?
The cohesive forces are greater than adhesive forces
What liquid property occurs because cohesive forces are stronger than adhesive forces?
Which liquid has a larger increase in surface area when incorporated in an emulsion?
The internal phase
When the surface area of the dispersed liquid increases during mixing of two immiscible liquids, what type of energy increases?
Surface free energy
The increase in surface free energy of the dispersed phase of two mixed immiscible liquids makes the system more or less stable?
- Thermodynamically unstable
What property makes two mixed immiscible liquids thermodynamically unstable?
The increase in surface free energy experienced by the dispersed liquid when its surface area increased during mixing
What are the three theories of emulsifications?
- Reduction of interfacial tension
- Formation of a rigid interfacial film
- Formation of an electrical double layer
Describe the emulsion theory of “Reduction of interfacial tension”:
Surfactants are used to decrease interfacial tension and make the emulsions more thermodynamically stable
Describe the theory of emulsions “Formation of a rigid interfacial film”:
The denser the interfacial film, the more stable the emulsion
Describe the emulsion theory of “Formation of an electrical double layer”:
Electrical barrier to particles approaching each other creates a stronger emulsion
What theory of emulsions states that an electrical barrier between particles increases the strength?
Formation of an electrical double layer
What theory of emulsions states that the denser the interfacial film, the more stable the emulsions?
Formation of a rigid interfacial film
What theory of emulsions states that Emulsions are more thermodynamically stable is surfactants are used to reduce the interfacial tensions?
Reduction of interfacial tension
Why are emulsifying agents used?
- To facilitate emulsification
- To promote emulsion stability
What is used to promote emulsion stability and the emulsification process?
What are the three types of emulsifying agents?
- Hydrophilic colloids
- Surface active agents
- Finely divided solids
Hydrophilic colloids, surface active agents and finely divided solids can all be used as what?
Where are surface active agents absorbed in an emulsion?
At the oil/water interface
What is the purpose of incorporating Surfactants into emulsions?
- To reduce the interfacial tension
- Electrical barrier to approach the particles
How many molecules thick are the films produced by surfactants?
Mono or multimolecular films
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