Definition of Multiple Emulsions:
- Multiple emulsions are complex systems where emulsions exist within emulsions. Common types include:
- W/O/W: Water-in-oil-in-water
- O/W/O: Oil-in-water-in-oil
Example (W/O/W):
- Internal water droplets are dispersed in oil droplets, which are further dispersed in an external water phase.
Applications:
- Controlled and sustained drug release
- Masking taste or odor
- Targeted drug delivery
- Cosmetics and vaccine delivery systems
Formulation Challenges:
- Difficult to stabilize due to the complexity of the system
- Requires carefully selected emulsifier combinations
- One for forming the internal emulsion (e.g., W/O)
- Another for stabilizing the external emulsion (e.g., O/W)
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