emulsions (2).ppt - EMULSIONS PHT 312 1 1 PHARMACEUTICAL...

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08/09/19 PHT 312 1 EMULSIONS 1
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PHARMACEUTICAL EMULSIONS 08/09/19 PHT 312 2
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Emulsion An emulsion consists of two immiscible liquids one of which is uniformly dispersed through the other as droplets of diameter greater than 0.1 m. The system is stabilized by the presence of emulsifying agent. The particle diameter of the disperse phase extends from 0.1 to 100 m. 08/09/19 PHT 312 3
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08/09/19 PHT 312 4
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08/09/19 PHT 312 5 Pharmaceutical application of emulsions: - Oral, rectal and topical administration of oils and oil- soluble drugs. - The unpleasant taste or odor can be masked by emulsification - The absorption and penetration of medicament are enhanced by emulsification - Intramuscular injections of water-soluble drugs or vaccine to provide slow release. - The use of sterile stable i.v emulsion containing fats, carbohydrates and vitamins as a potential nutrition
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Examples: Oral use : Cod-liver, Liquid paraffin, castor oil emulsions External use Turpentine Liniment BP, Oily calamine lotion BP. 08/09/19 PHT 312 6
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DIFFERENCE BETWEEN O/W AND W/O EMULSIONS Oil in water emulsion (o/w ( Water in oil emulsion (w/o ( Water is the dispersion medium and oil is the dispersed phase Oil is the dispersion medium and water is the dispersed phase They are non greasy and easily removable from the skin surface They are greasy and not water washable They are used externally to provide cooling effect e.g. vanishing cream They are used externally to prevent evaporation of moisture from the surface of skin e.g. Cold cream Water soluble drugs are more quickly released from o/w emulsions Oil soluble drugs are more quickly released from w/o emulsions They 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 .
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Test for identification of emulsion type: Dilution test (miscibility test) Staining test (dye solubility test) Conductivity measurement CoCl2 filter test Fluorescence test 08/09/19 PHT 312 8
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08/09/19 PHT 312 9
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08/09/19 PHT 312 10 Conductivity Test This test is based on the basic principle that water is a good conductor of electricity. Therefore in case of o/w emulsion , this test will be positive as water is the external phase. In this test. An assembly consisting of a pair of electrodes connected to a lamp is dipped into an emulsion. If the emulsion is o/w type, the lamp glows.
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08/09/19 PHT 312 11 Dye Solubility Test In 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.
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