Liquid dosage forms - emulsion Flashcards
What are the types of emulsions?
O/W - oil in water where oil is dispersed in the continuous water.
W/O - water in oil where water is dispersed in the continuous oil.
Clinical oral applications for emulsions?
O/W - mask the taste of an oil (mineral oil emulsion as a laxative)
W/O - enhance absorption of an oil (vitamin A and D, cod liver oil)
How does interfacial tension work and how do surfactants alter the interfacial tension?
Molecules situated at the interface experience unequal interaction forces different than those in the bulk of the phase.
Liquid systems this imbalance leads to spontaneous movements of the molecules from the interface to the bulk phase.
Now there are fewer molecules per unit area at the interface.
Reversal of the spontaneous movement of molecules at the interface (by increasing the area of contact between phase) causes the interface to resist expansion and behave as if it is under tension everywhere.
-the force of this tension per unit length is call interfacial tension
Surfactants are amphiphilic and are added to reduce the interfacial tension by interacting with both phases and creating stability.
What is the role of interfacial tension in production of an emulsion and stability of that emulsion?
What is important to know about the formation of micelles in solutions of surfactants and their unity?
What is important to know about the mechanisms by which surfactants, hydrophilic colloids and finely divided solids act as emulsifying agents?
What is the basis of physical instability of emulsions?
How can you predict the type of emulsion by using the formula?
What are the typical components of an emulsion and how to manufacture it?
Clinical external applications for emulsions?
O/W - water washable, vanishing cream
W/O - for cleansing skin, cold cream
Clinical intravenous applications for emulsions?
For parenteral nutrition
Smallest capillaries are 5 micromolar so it is important that droplet size is less than 1 micromolar to avoid embolisms
