Instability of emulsion

Deviation from the ideal behavior of an emulsion is known as instability of emulsion.
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1. Instability of emulsion Shaikh Ashraful Alam Course Title: Pharmaceutical Technology & Dispensing Course Code: ACCE-420 Applied Chemistry & Chemical Engineering

2. Instability of emulsion Deviation from the ideal behavior of an emulsion is known as instability of emulsion.

3. Classifications Various type of instability arises in pharmaceutical emulsion. These are, Cracking or Breaking Creaming Determination by microorganism Physical and chemical changes.

4. Cracking or Breaking When the phases of an emulsion are separated as two distinct layer, it is known as cracking or breaking. Causes of cracking: Addition of an emulsifying agent of opposite type Decomposition or precipitation of emulsifying agent Temperature Freezing Addition of a common solvent

5. Cracking or Breaking(con..) Prevention of cracking Absence of incompatibility between emulsifying agent and other ingredient. Absence of excessive amount of dispersed part Absence of increase temperature Absence of freezing of the aqueous phase

6. Creaming Creaming is rising or setting of dispersed globules to form a concentrated layer at the surface and the bottom of the emulsion. Causes of creaming: It is cause by the influence of gravity of the globules. Since they have different density from that of continuous phase. Types of creaming: Downward creaming Upward creaming

7. Creaming: Downward creaming Globule settle to the lower layer if they have a greater density than the continuous phase. It is Common in w/o emulsion

8. Creaming: Upwnward creaming If the globules have lower density ,they will tend to concentrate the upper layer of the system and it is called upward creaming. This is common in o/w emulsion e .g Creaming of milk

9. Prevention of Creaming By reducing the size of globules By reducing density difference By increasing the viscosity of continuous phase

10. Deterioration by microorganism Most emulsion are sensitive to growth of bacteria, yeast and mold, because emulsifying agent is suitable media for growth of microorganism. Cause; Decomposition of emulsifying agent Contaminate of aqueous phase Produce rancidity of the oil Density oil soluble vitamin

11. Protection: Deterioration by microorganism To protect these ,preservation should be added. A mixture of parahydro benzoil (0.1~0.2%), methylester and propyl ester (0.02~0.05%) are particularly effective against mold,east and bacteria.

12. Miscellaneous physical and chemical change Various physical and chemical changes included- Deterioration of light Deterioration caused by extreme temperature Oxidative and hydrolytic ranicidity of the oil. Change of PH

13. Prevention of Miscellaneous physical and chemical change Antioxident should be used. It should be preserved at closed container It should be kept in an ambored colored.