Emulsion Dosage Forms Flashcards
What is an emulsion?
A pseudo stable dispersion of at least two immiscible liquids, one of which is dispersed throughout the other in the form of fine droplets stabilised by the presence of a n emulsifying agent.
What are the three emulsion types?
Normal emulsion (o/W)
Reverse emulsion (W/o)
Multiple emulsions (o/W/o or W/o/W)
What are creams?
Semi solid emulsions of two immiscible phases stabilised by emulsifying agent
What are the factors of o/W creams?
Water is the bulk phase
Non-occlusive
Can conduct electricity
Prepared using surfactant with higher HLB (8-16)
What are the factors of W/o creams?
Oil is the bulk phase
Miscible with oil
Does not conduct electricity
Prepared using low HLB surfactants (3.5-8)
What is the value of water in ointment, cream and lotion?
Increase of water in lotion
Decrease of water in ointments
What test can you do to differentiate between o/W and W/o emulsions?
Dry solubility test
Dilutions of emulsions with water and oil
Conductivity
Fluorescence
What is the dry solubility test?
Mix emulsion with a water-soluble dye (amaranth) and observe under a microscope.
Continuous phase red= o/W type
Scattered globules red= W/o type
What is the dilutions of emulsions with water or oil test?
If emulsion is o/W type
Diluted with water= remain stable
Diluted with oil= emulsion will break
What is the conductivity test?
The electrical current is supplied through electrodes placed in the emulsions.
If current is passed= o/W type
Not passed= w/o type
What is the fluorescence test?
Based on the fluorescence of oils under ultraviolet light, examined under the light in the microscope
Whole fluid is fluorescent= W/o type
Spotty fluorescent = o/W type
What is Hydrophile-Lipophile Balance (HLB)?
An empirical approach to aid the choice of surfactants for a particular purpose.
What is the strategy for emulsification in terms of using HLB?
To match the HLB of the oil phase being emulsified and the HLB of the surfactants.
what are the characteristics of emulsions?
cloudy or milky
droplet sizes are polydispersable
low concentration of surfactant/cosurfactant
thermodynaically unstable but kineticaly stable
prepared by input of large amount of enery
