Physically Instability of Emulsion | Pharmacy Notes

 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

Also Read…

Introduction to Emulsion

Type of Emulsion

Identification of Emulsion

Formulation of Emulsion

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