1.Flocculation:
- Neighboring globals come closer to each other ⇒ forms Flocs
- Re-Dispersed on shaking
- Prevented by imparting charges on globules and using uniform-sized globules
2.Creaming:
- Occurs Due to the density difference
- Upward creaming-O/W emulsion
- Downward creaming-W/O emulsion
- If Creaming occurs, Drug is not uniformly distributed ⇒ variable in dosage ⇒ emulsion should be shaken for only before use
3. Coalescence:
- Globules tend to fuse with each other and forms bigger globules and ultimately lead to the breaking of the emulsion
- Occurs due to destruction of emulsifier film around the globules due to insufficient agent or by temperature change or By the presence of micro-organism, or by creaming
4. Breaking:
- Complete separation of aqueous and oil phases
- Irreversible step
5. Phase inversion:
- Change of emulsion type from O/W to W/O and vice versa
Important Points
- Vanishing cream: O/W type emulsion.
- Cold Cream: W/O type emulsion
- Parenteral Preparation: Lecithin (Non-ionic) emulsifying agents
- Wedge Thory:
- Monovalent soap (Sodium stearate)- O/W type emulsion
- Divalent Soap (Calcium stearate)- W/O type emulsion