Emulsification enables the pharmacist to prepare relatively stable and homogeneous mixtures of two immiscible liquids. Emulsification enables the pharmacist to prepare relatively stable and homogeneous mixtures of two immiscible liquids.

1. EMULSI ONS
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2. An emulsion is a liquid preparation
consisting of two immiscible liquids, one of
which is dispersed in form of small globules
into the other liquid in the presence of an
emulsifying agent.
Introduction
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3. Dispersed phase
Also called the internal phase.
It is present in small quantity.
Liquid which is dispersed in the form of small globules is
called dispersed phase.
Dispersion medium
Also called the external
or continuous phase.
It is present in large quantity.
The liquid in which particle globules are dispersed is
called dispersion medium.
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4. Types OF EMULSIONS
Simple emulsions
O/W emulsion
W/O emulsion
Complex emulsions
W/O/W emulsion
O/W/O emulsion
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5. BLUE BIRD(PHARM-D) 5

6. O/W EMULSION
Emulsions with an oleaginous internal phase
and an aqueous external phase are oil-in-water
(o/w) emulsions.
Example
Vanishing Creams
Milk
• This emulsion can be identified by its electrical
conducting nature Since water is a good
conductor, when an electrode is placed, it shows
conductivity, indicating it to be external phase.
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7. W/O EMULSION
Emulsions having an aqueous internal phase
and an oleaginous external phase are termed
water-in-oil (w/o) emulsions.
Example
Cold Creams
• They can be identified by
adding oil soluble dyes. If
oil soluble, the dye colors
the whole solution.
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8. BLUE BIRD(PHARM-D) 8

9.  W/O/W EMULSION
double emulsion in which oil droplets enclosing
water droplets are dispersing in water
 O/W/O EMULSION
water is center most layer while oil occupies
inner most and also outer most layer.
 They are known as double emulsions
 These are prepared for drugs having
Low permeability
Less solubility
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10.  Emulsion may be prepared as
Liquid
Semi solid
depending upon the constituents of emulsifying
agent.
 Based upon the constituents, liquid emulsion ay
be used
Orally
Topically
Parenterally
while semisolid emulsion used
topicallyBLUE BIRD(PHARM-D) 10

11. Emulsification enables the pharmacist to
prepare relatively stable and homogeneous
mixtures of two immiscible liquids.
To enhance the oral acceptability of oils
To mask bitter taste of oil soluble as well
as water soluble drugs by constituting o/w
or w/o emulsion respectively.
To enhance therapeutic efficacy of drug
To decrease irritation of product applied
over the skin
PURPOSE OF EMULSIFICATION
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12. Emulsions to be applied to the skin may be o/w or w/o,
depending on factors as:
the nature of the therapeutic agents,
the desirability for an emollient or tissue-
softening effect
the condition of the skin
PURPOSE OF EMULSIFICATION
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13. ADVANTAGES
Mask The Unpleasant Taste O/W Is Convenient
Means Of Oral Administration Of Water-insoluble
Liquids.
Oil-soluble Drugs Can Be Given Parentrally In
Form Of Oil-in Water Emulsion. (E.G Taxol).
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14. Emulsion Can Be Used For External
Application In Cosmetic And Therapeutic
Application Because Of Better And Faster
Absorption.
Sustained Release Medication.
Nutritional Supplement.
Inert And Chemically Non-reactive.
Reasonably Odorless And Cost Effective.
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15. Radiopaque agents for diagnostic purposes.
Intravenous nutrition (maintenance of
debilitated patients)
Fluorocarbon emulsions- fluorocarbons
have high capacities for dissolving gases like
O2 and CO2 and serve as blood substitutes for
a short period of time.
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16. Emulsions are thermodynamically
unstable and have short shelf-life.
Improper formulation of emulsions leads
to creaming and cracking of emulsion.
Improper selection of emulsifying agent
leads to phase inversion and some times it
may also lead to cracking.
DISADVANTAGES
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17. Many theories have been advanced in an attempt to explain
how emulsifying agents promote emulsification and maintain
the stability of the emulsion.
 Among the most prevalent theories are
THE SURFACE TENSION THEORY
THE ORIENTED-WEDGE THEORY
THE PLASTIC OR INTERFACIAL FILM
THEORY
THE ELECTRON REPULSION THEORY
THEORIES OF EMULSIFICATION
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18. All liquids have a tendency to assume a shape having
the minimal surface area exposed. For a drop of a
liquid, that shape is the sphere.
 A liquid drop has the shape of a sphere. It possesses
internal forces that tend to promote association of the
molecules to resist separation of the sphere.
 If two or more drops of the same liquid come into
contact with one another, the tendency is for them to
join or to coalesce, making one larger drop of less
surface area than the total surface area of the
individual drops.
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19. SURFACE TENSION
This tendency of liquids may be measured
when the surrounding of the liquid is air, it
is referred to as the liquid’s surface tension.
INTERFACIAL TENSION
 When the liquid is in contact with a second
liquid in which it is insoluble and
immiscible, the force causing each liquid to
resist breaking up into smaller particles is
called interfacial tension.
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20. SURFACE ACTIVE AGENTS
Substances that reduce this resistance
encourage a liquid to break up into smaller
drops or particles. These tension-lowering
substances are surface-active (surfactant) or
wetting agents.
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21. According to the surface tension theory of
emulsification, the use of these substances as
emulsifiers and stabilizers lowers the interfacial
tension of the two immiscible liquids, reducing
the repellent force between the liquids and
attractive forces between the same molecules.
 Thus, the surface active agents facilitate the
breaking up of large globules into smaller ones,
which then have a lesser tendency to reunite or
coalesce.
THE SURFACE TENSION THEORY
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22. The theory is based on the presumption that certain
emulsifying agents orient themselves on the basis of their
solubility in that particular liquid.
Emulsifier shaped like a wedge and have
Hydrophilic or water loving portion
Hydrophobic or water hating portion
THE ORIENTED-WEDGE THEORY
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23. Generally, an emulsifying agent having greater hydrophilic than
hydrophobic nature will promote an o/w emulsion while
emulsifying agent having more hydrophobic nature than
hydrophilic, it will promote w/o emulsion.
THE ORIENTED-WEDGE THEORY
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24. Polar or hydrophilic group orient itself
towards aqueous phase while non polar or
hydrophobic orients towards oil phase
This theory didn’t fully depicted the molecular
arrangement of emulsifiers.
THE ORIENTED-WEDGE THEORY
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25. The plastic or interfacial film theory places the
emulsifying agent at the interface between the oil
and water, surrounding the droplets of the internal
phase as a thin layer of film adsorbed on the
surface of the drops.
THE PLASTIC OR INTERFACIAL FILM
THEORY
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26. The film prevents contact and coalescing of the
dispersed phase; the tougher and more
pliable/multilayered the film, the greater the
stability of the emulsion.
water-soluble agents encouraging o/w emulsions
and oil-soluble emulsifiers encouraging w/o
emulsions
The plastic or interfacial film theory
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27. This theory is based on the charge (+/-) on
dispersed phase particles
If the dispersion medium is water ( containing both
+/- charge) then charge opposite to dispersed phase
starts accumulating on its surface.
THE ELECTRON REPULSION THEORY
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28. If the negative charge on dispersed phase
then positive charge of water will be
attracted and form a layer of positive
charges over the negative ones and on
their surroundings negative charge of
water starts depositing.
Negative on outer will repel negative
charge of oil so no coalescence will occur
and hence stabilize the emulsions.
THE ELECTRON REPULSION THEORY
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