4 Types of Emulsions in Pharmacy with Examples
Emulsions are bi-phasic liquid solutions.
They are used for drug delivery in medicine, cleaning of oil and greasy surfaces, storage of substances, etc.
The routes of medication administration by which emulsions are given include by oral, parenteral and even few topical preparations (creams).
They are a bit advanced in terms of their stability and making.
One liquid phase is evenly spread in the other liquid phase.
The one which is a large proportion is called the external phase while the one which is in lower proportions is called internal phase.
The internal phase and external phase liquids are insoluble.
But they are made to mingle with each other by some surface property alteration.
The internal phase liquid is converted to small droplets with a suitable coating. This coating helps the internal phase to admix with the external phase.
If the bonding layer is destroyed, the emulsions break up leaving two immiscible liquids.
Types of emulsions:
Emulsions are basically of two types. But due to the careful mixture, they can be made into 2 more types.
The first type is called simple emulsions. They are as
- W/O types emulsions
- O/W type of emulsions.
The other type is called as complex emulsions. They are again of two types as
- W/O/W type emulsions
- O/W/O type of emulsions.
W/O type of emulsions:
These emulsions are the type wherein water is an internal phase and oil is an external phase. They can be identified by adding oil-soluble dyes. If oil soluble, the dye colors the whole solution.
O/W type of emulsion:
These emulsions have oil as an internal phase and water is in the external phase. This emulsion can be identified by its electrical conducting nature. Since water is a good conductor, when an electrode is placed, it shows conductivity, indicating it to be an external phase.
W/O/W type of emulsions: Here water comprises two layers while oil is a center layer.
O/W/O type of emulsions: Here water is centermost layer while oil occupies innermost and also outer most layer.