EmulsionAn emulsion consists of two immiscible liquids one of which isuniformly dispersed through the other as droplets of diametergreater than 0.1m.The system is stabilized by the presence of emulsifying agent.The particle diameter of the disperse phase extends from 0.1to 100m.08/09/19PHT 3123
08/09/19PHT 3125Pharmaceutical application of emulsions:- Oral, rectal and topical administration of oils andoil-soluble drugs.- The unpleasant taste or odor can be masked byemulsification- The absorption and penetration of medicament areenhanced by emulsification- Intramuscular injections of water-soluble drugs orvaccine to provide slow release.- The use of sterile stable i.v emulsion containing fats,carbohydrates and vitamins as a potential nutrition
DIFFERENCE BETWEEN O/W AND W/O EMULSIONSOil in water emulsion (o/w(Water in oil emulsion (w/o(Water is the dispersion medium and oil is the dispersed phaseOil is the dispersion medium and water is the dispersed phaseThey are non greasy and easily removable from the skin surfaceThey are greasy and not water washableThey are used externally to provide cooling effect e.g. vanishing creamThey are used externally to prevent evaporation of moisture from the surface of skin e.g. Cold creamWater soluble drugs are more quickly released from o/w emulsionsOil soluble drugs are more quickly released from w/o emulsionsThey are preferred for formulations meant for internal use as bitter taste of oils can be masked.They are preferred for formulations meant for external use like creams. O/W emulsions give a positive conductivity test as water is the external phase which is a good conductor of electricity.W/O emulsions go not give a positive conductivity test as oil is the external phase which is a poor conductor of electricity.
Test for identification of emulsion type:Dilution test (miscibility test)Staining test (dye solubility test)Conductivity measurementCoCl2 filter testFluorescence test08/09/19PHT 3128
08/09/19PHT 31210Conductivity TestThis test is based on the basic principle that water is a good conductor ofelectricity. Therefore in case of o/w emulsion , this test will be positive aswater is the external phase. In this test. An assembly consisting of a pairof electrodes connected to a lamp is dipped into an emulsion. If the emulsionis o/w type, the lamp glows.
08/09/19PHT 31211Dye Solubility TestIn this test, when an emulsion is mixed with a water soluble dye such as amaranth and observed under the microscope, if the continuous phase appears red, then it means that the emulsion is o/w type as water is the external phase and the dye will dissolve in it to give color but if the scattered globules appear red and continuous phase colorless, then it is w/o type.