This slide deck gives information about the basic concept of the emulsion dosage form. It includes types of emulsions, stability concerns, identification tests, stability improvisation techniques and concept of preservation.

1. BASICS OF
EMULSIONS
HEMANTH KG
MPharm (Pharmaceutics)

2. Introduction
MICROSCOPIC IMAGE OF EMULSION
2. Coarse dispersion
3. Diameter range of 0.1 to 100 μm
1. Biphasic systems
o/w: Oil globules in water
Internal External
w/o: water globules in oil
Internal External
FINE EMULSION
Globule size: 0.25 to 25 μm
Appearance: Milky
MICRO EMULSION
Globule size: 1 to 100 nm
Appearance: Transparent
NANO EMULSION
Globule size: 1 to 100 nm
Appearance: Transparent

3. Examples of Emulsions
o/w w/o

4. Markers of Instability
Flocculation Coalescence Creaming BreakingPhase inversion
Downward-w/o
Upward-o/w
Flocs
Flocs

5. Thermodynamic Instability
• Low surface free energy-Stable
• Higher interfacial area-higher interfacial energy-Less stable
• Globules possess high surface area compared to its original surface area
• Globules try going back to original state thereby decreasing ΔA so that
ΔG will be zero-Coalescence-Unstable
• γo/w may be reduced but cant be made zero-dispersed phase certain +ve
interfacial tension.
• So ΔG can’t be made Zero
• γo/w can be made minimum by adding Surface active agents-Emulsifying
agents
ΔG=increase in surface free energy
γo/w = interfacial tension of oil-water interface
ΔA = increase in surface area of the interface due to droplet
formation
ΔG = γo/w ΔA

6. Appearance and identification tests
Other tests are
• Ferric chloride test,
• Fluorescence test,
• Filter paper test, with limitations
Dye solubility test
Amaranth dye
Water soluble dyes:
Amaranth
Methylene blue
Oil soluble dyes:
Sudan III
Scarlet red
Dilution test
o/w w/o
Water
o/w
Conductivity test
o/w- Bulb glows
w/o- Bulb doesn’t glow
Creaming test
o/w
Upward
Creaming
w/o
Downward
Creaming
These are the standard tests which
give authentic results.

7. How to improve stability ?
5. Temperature fluctuations:
• Chemical degradation
• o/w-Water evaporation-concentrated
• Low temp-ice crystals
• Decrease viscosity
2. Particle size:
• Globule size , Brownian movement
• Stokes’ law-diameter of globule is major factor
• 4 fold Creaming , globule diameter ½
• Optimum globule size-max stability
3. Particle size distribution:
• Uniform globule size-loosely packed, less contact
• Uniform globule size-small globules occupy voids of larger globule: Coalescence
• Monodisperse system-difficult, hence optimum degree of size distribution
1. Viscosity:
• As viscosity , flocculation
• Brownian movement , leading to creaming
• Hence, optimum viscosity is desired
4. Phase volume ratio:
• Relative volume of w/o
• Max 74% oil-lead to breaking
• Critical point-conc of internal phase above which-instability
• Beyond critical point-irregular globule shapes-coalescence

8. Preservation
• Carbohydrates, proteins, sterols and gums are present in emulsions
• Microbes: fungi, bacteria, yeast use for their growth and cause instability
• Parenteral emulsion: Sterility must
• Hence optimum preservative quantity is added.
• E.g. Benzoic acid, sodium benzoate, methyl paraben, propyl paraben

9. Marketed emulsions

10. THANK YOU