EMULSION

Emulsions
Physical Pharmacy-I

Course contents
•Definition
•Types of Emulsion
•Theories of emulsification
•Emulsifying agents and their classification
•Methods of preparation
•Stability of emulsion
•Applications

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Emulsion
“A thermodynamically unstable system consisting of at least
two immiscible liquid phases, one of which is dispersed as
globules (the dispersed phase) in the other liquid phase
(the continuous phase), stabilized by the presence of an
emulsifying agent.”

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Oil

Water
Oil in Water
(O/W) Emulsion
Water in Oil (W/O)
Emulsion
OIL IN WATER (O/W) OR WATER IN OIL (W/O)
EMULSION
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•In case of emulsions,
One liquid phase is essentially polar (e.g., aqueous), whereas
the other is relatively nonpolar (e.g., an oil).
The dispersed phase is a liquid that is neither soluble nor
miscible with the liquid of the dispersing phase.
The particle diameter of the dispersed phase generally
extends from about 0.1 to 10 μm.
To prepare a stable emulsion, a third phase, an emulsifying
agent, is necessary.
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•Emulsified systems range from lotions (relatively low
viscosity) to ointments and creams (semisolid)
•Route of Administration: Based on the constituents and
the intended application:
Liquid emulsions: orally, topically, or parenterally
Semisolid emulsions: topically
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Emulsifier
A B

Advantages

Poorly water soluble drugs may be easily incorporated with
improved dissolution rate and bioavailability.
Unpleasant taste and odor of oils can be masked partially or
wholly by emulsification.
Absorption rate and permeation of medicament can be
controlled.
Formulation and technology for organ targeted delivery is
available.

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TYPES OF EMULSION
A.Simple emulsion (w/o, o/w)
B.Multiple emulsion (w/o/w, o/w/o)
C.Micro emulsion/ Nano emulsions

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a. Simple emulsions
•Simple emulsions are classified as:
i.Oil-in-water (o/w) Emulsion: System in which the oil phase is
dispersed as globules throughout an aqueous continuous
phase (diluted with aqueous phase)
ii.Water-in-oil (w/o) Emulsion: System in which the aqueous
phase is dispersed as globules throughout the continuous oil
phase (diluted with oleaginous phase)

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i. Oil-in-water (o/w) Emulsion
•The common daily life example is milk.
•These emulsions are used mainly for internal/oral
use (as bitter or disagreeable taste and odor of
drugs can be masked by emulsification)
•Externally these emulsions are used for formulating
non greasy creams, lotions and liniments.
•Cosmetic products prepared using o/w emulsions
can easily be removed from the surface of the skin .
•Example: Castor oil emulsion, foundation creams,
vanishing cream.

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ii. water-in-oil (w/o) Emulsion
They are mainly used externally as lotions
and creams as the external layer of oil
forms an occlusive layer and prevents the
evaporation of moisture from the surface
of the skin.
They are also effective as cleansing cream
as they solubilize the oil soluble dirt from
the surface.
Example: Cold creams, oily calamine
lotion

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•Medicinal emulsions for oral administration are usually of the o/w
type and require the use of an o/w emulsifying agent (synthetic
nonionic surfactants like acacia, tragacanth, and gelatin)
•Most emulsions belong to the o/w type. Certain foods such as butter
and some salad dressings are w/o emulsions.

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No. Oil-in-water (o/w) Emulsion Water-in-oil (w/o) Emulsion
1
Water: Dispersion medium
Oil: Dispersed phase
Oil: Dispersion medium
Water: Dispersed phase
2 For water insoluble drug For water soluble drug
3 Have non-greasy texture Have greasy texture
4 Easy to wash from skin Difficult to wash from skin
5
Water soluble drugs are more quickly
released from o/w emulsions
Oil soluble drugs are more quickly released
from w/o emulsions
6
They are preferred for formulations
meant for internal use as bitter taste
of oils can be masked.
They are preferred for formulations meant
for external use like creams.
7 Better consumer compliance Less consumer compliance
8 Vanishing cream, mayonnaise Cold cream, butter

b. Multiple emulsion
•Multiple emulsions are emulsions whose disperse phase contains
droplets of another phase (emulsion system).
• They are made by emulsifying water-in-oil emulsion with a hydrophilic
surfactant to produce a water-in-oil-in-water system, or an oil-in-water
system with lipophilic surfactant to produce an oil-in-water-in-oil
system.
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•Route of Administration: Water-in-oil-in-water (w/o/w) emulsions in
which a water-soluble drug is dissolved in the aqueous phase may be
injected by the subcutaneous (SC) or intramuscular (IM) routes to
produce a delayed action preparation. To escape, the drug has to
diffuse through the oil to reach the tissue fluids, hence the delayed-
release action.

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c. Micro emulsion
•Microemulsions are thermodynamically stable, optically
transparent mixtures of a biphasic o/w system stabilized
with surfactants.
•Diameter of droplets in microemulsion= 100 Å (10
millimicrons) to 1000 Å, ( about 10-200nm), whereas in a
macroemulsion= 5000 Å in diameter.
•Both o/w and w/o microemulsions may be formed
spontaneously by agitating the oil and water phases with
carefully selected surfactants.
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•The type of emulsion produced depends on the properties of the oil
and surfactants.
•An emulsifying adjunct or co-surfactant is used in the preparation of
microemulsions.
•The surfactant and co-surfactant molecules form an adsorbed film on
the microemulsion particles to prevent coalescence.
•EXAMPLE: An anionic surfactant (sodium lauryl sulfate or potassium
oleate), can be dispersed in an organic liquid (such as benzene), a
small measured amount of water is added, and the microemulsion is
formed by the gradual addition of a lipophilic cosurfactant
(pentanol), to form a clear solution at 30⁰C.
The addition of pentanol temporarily reduces the surface tension
to approximately zero, allowing spontaneous emulsification.

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•Advantages of microemulsions in drug delivery are:
More rapid and efficient oral absorption of drugs than through
solid dosage forms,
Enhanced transdermal drug delivery through increased diffusion
into the skin, and
The unique potential application of microemulsions in the
development of artificial red blood cells and targeting of cytotoxic
drugs to cancer cells.
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Types of emulsion

Identification of type of emulsion
•As it is difficult to distinguish emulsion type from naked
eye, hence different tests are used to identify the type of
emulsion, the test includes:
1)Dye solubility test
2)Dilution test
3)Electrical conductivity test
4)OTHERS

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1. Dye solubility test
•A small quantity of a water-soluble dye such as methylene
blue or brilliant blue FCF may be dusted on the surface of the
emulsion.
• If water is the external phase (i.e., if the emulsion is of the
o/w type), the dye will dissolve and uniformly diffuse
throughout the water.
•If the emulsion is of the w/o type, the particles of dye will lie
in clumps on the surface.

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2. Dilution test
•A second method involves dilution of the emulsion with
water. If the emulsion mixes freely with the water, it is of
the o/w type.

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3. Electrical conductivity test
•Connect a pair of electrodes to an external electric source and
immerse in the emulsion.
•If the external phase is water, a current will pass through the
emulsion and can be made to deflect a voltmeter needle or cause a
light in the circuit to glow.
•If the oil is the continuous phase, the emulsion fails to carry the
current.

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Theories of emulsification
•There is no universal theory of emulsification because
emulsions can be prepared using several different types of
emulsifying agent, each of which depends for its action on a
different principle to achieve a stable product.
•For a theory to be meaningful, it should be capable of
explaining
(a) stability of the product and
(b) type of emulsion formed.
A.Surface tension theory
B.Oriented-wedge theory
C.Interfacial film (Plastic) theory

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Surface tension
•The molecules at the surface of water are not completely surrounded
by other molecules as they are in the bulk of the water.
• As a result there is a net inward force of attraction exerted on a
molecule at the surface from the molecules in the bulk solution,
which results in a tendency for the surface to contract.
•This contraction is spontaneous and represents a minimum free
energy state.
•We express the strength of contraction by the work required to
increase the surface area by 1 meters square; this is referred to as
the surface tension.”
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•Surface tension is the force per unit length existing at
the surface of a liquid and Interfacial tension is the
force per unit length existing at the interface between
two immiscible liquid phases.
•Units of surface and interfacial tension: N/ m.
•The attractive force exerted upon
the surface molecules of a liquid by the molecules
beneath that tends to draw the surface molecules into
the bulk of the liquid and makes the liquid assume the
shape having the least surface area.

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a. surface tension theory of emulsification
•According to the surface tension theory of emulsification, the
use of emulsifiers and stabilizers lowers the interfacial
tension of the two immiscible liquids, reducing the repellent
force between the liquids and diminishing each liquid’s
attraction for its own 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.
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b. oriented-wedge theory
•The oriented-wedge theory assumes monomolecular layers of
emulsifying agent curved around a droplet of the internal phase
of the emulsion.
•The theory is based on the presumption that certain emulsifying
agents orient themselves about and within a liquid in a manner
reflective of their solubility in that particular liquid. (wedge shape)
•Generally, an emulsifying agent having a greater hydrophilic
character will promote an o/w emulsion, and a w/o emulsion
results from use of an emulsifying agent that is more hydrophobic
than hydrophilic.
•Putting it another way, the phase in which the emulsifying agent is
more soluble will become the continuous or external phase of the
emulsion.
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c. The plastic or interfacial film theory
•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 internal phase.
•The film prevents contact and coalescing of the dispersed phase.
•The tougher and more pliable the film, the greater the stability
of the emulsion.
•The formation of an o/w or a w/o emulsion depends on the
degree of solubility of the agent in the two phases, with water-
soluble agents encouraging o/w emulsions and vice versa.
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Theories of emulsification- SUMMARY

•In actual, it is unlikely that a single theory of
emulsification can explain the means by which the
many and varied emulsifiers promote emulsion
formation and stability.
•Lowering of the interfacial tension is important in the
initial formation of an emulsion, but the formation of a
protective wedge of molecules or film of emulsifier is
important for continued stability.
•No doubt certain emulsifiers are capable of both tasks.
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Preparation of Emulsions
•Emulsions may be prepared by several methods,
depending upon the nature of the components and the
equipment.
•On a small scale, as in the laboratory or pharmacy,
emulsions may be prepared using
a dry Wedgwood or porcelain mortar and pestle,
a mechanical blender or mixer, such as a Waring
blender or a milkshake mixer,
a hand or bench-type homogenizer (Fig. 14.9), (Fig.
14.10),
or sometimes a simple prescription bottle.
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Hand Homogenizer
Bench-type Homogenizer

On Large Scale
•Large mixing tanks (Fig. 14.5) may be used to
form the emulsion through the action of a high
speed impeller.
•As desired, the product may be rendered finer by
passage through colloid mill, in which the
particles are sheared between the small gap
separating a high-speed rotor and the stator,
•or by passage through a large industrial
homogenizer (Capacity=100,000 L of product per
hour), in which the liquid is forced under great
pressure through a small valve opening.

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Mixing tanks

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Colloidal mill
Impellers
Industrial homogenizer

preparation of emulsions
The initial step in preparation of an
emulsion is selection of the Emulsifying
Agent….

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What happen when two immiscible liquids are
agitated together?
1.Failure of the two liquids to remain mixed
2.The increase in the surface energy makes the
system thermodynamically unstable,

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To prevent this coalescence:
•Introduce third material (Emulsifying agent), which
form a film around the dispersed globules and prevent
them from coming close to each other and form larger
globules.

Oil
Water

Emulsifying agents
•These agents helps in the production
of stable dispersion by reducing
interfacial tension and then
maintaining the separation of the
droplets by forming a barrier at the
oil water interface.
•Effective emulsifying agents are
surface-active agents, these have
hydrophilic groups which are
oriented towards water, and
lipophilic non-polar toward oil.
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Emulsifying agents
•Emulsion type is determined by the solubility of the
emulsifying agent:
if the emulsifying agent is more soluble in water, (i.e.
hydrophilic) then water will by the continuous phase and
O/W emulsion will formed,
If the emulsifying agent is more soluble in oil, (i.e.
hydrophobic) then oil will by the continuous phase and
W/O emulsion will formed,
•If some material is added which alters the solubility of the
emulsifying agent, this balance may be altered and the
emulsion may change type.
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Selection of Emulsifier
• An ideal emulsifier must be:
Compatible with the other formulation ingredients
Must not interfere with the stability or efficacy of the
therapeutic agent.
Stable and not deteriorate in the preparation.
Nontoxic with respect to its intended use and the
amount to be consumed by the patient.
Contribute insignificant odor, taste, or color.
Possess the capability to promote emulsification and to
maintain the stability of the emulsion for the intended
shelf life of the product.

Classification of Emulsifying agents
•There are different ways to classify
emulsifiers or emulgants; like on the
basis of:
a.Chemical nature of the emulsifier
b.Type of film the emulsifiers form

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b. Type of film the emulsifiers form

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Hydrophile-lipophile balance (HLB)
•The hydrophile–lipophile balance (HLB) number is a
measure of the balance between hydrophobic and
hydrophilic portions of a surfactant.
•In selecting a surfactant for emulsion stabilization, it is
essential that there is a degree of surfactant
hydrophilicity and hydrophobicity.
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Hydrophile-lipophile balance (HLB)
•The usual range of HLB is between 1 to 20.
•Material that are highly polar or hydrophilic
have higher number of HLB than materials
that are less polar or lipophilic which have low
number of HLB.
•Materials having an:
HLB value (3-6) are lipophilic & produce W/O.
HLB value (9-18) are hydrophilic and produce O/W.

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Rule of Bancroft
•The type of emulsion is a function of the relative solubility of
the surfactant, the phase in which it is more soluble being the
continuous phase.
•Emulsifying agent with a high HLB is soluble in water and results
in the formation of an (O/W) emulsion.
•The reverse situation is true with surfactant of low HLB, which
tend to form (W/O) emulsions.
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Emulsifying agent HLB value
Acacia 8.0
Sorbitan monolaurate 8.6
Sorbitan monostearate 4.7
Polysorbate 20 16.7
Polysorbate 60 14.9
Polysorbate 80 15.0
Sodium lauryl sulphate 40.0
Sodium oleate 18.0
Tragacanth 13.2
Triethanolamine oleate 12
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EMULSIFIERS
1. NATURAL
EMULGENTS
a) Carbohydrate
Materials
b) Protein
Substances
2. SYNTHETIC
EMULGENTS
a) Non-ionic
Emulgents
b) Ionic
Emulgents
3. OTHERS
Finely Divided
Solids
a.Chemical nature of the emulsifier

1) Natural emulgents or
Naturally Occurring Emulsifying Agents
a)Carbohydrate Materials

Example: Acacia, Tragacanth, Agar, Pectin
•They form hydrophilic colloids (i.e. multimolecular
film) when added to water and generally give O/W
emulsion.
•Acacia- commonly used in the preparation of
Extemporaneous emulsions
•Tragacanth and agar- Thickening agents in acacia-
emulsified products
•Microcrystalline cellulose (semi-synthetic
polysaccharides)- Viscosity regulator

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1) Natural emulgents or
Naturally Occurring Emulsifying Agents
b) Protein substances

Example: Gelatin, Egg yolk, Casein

•These substances give O/W emulsion.

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Gelatin
Collagen (Animal raw
tissues)
Egg Yolk Lecithin (Phospholipid)
Casein Milk proteins

2) Synthetic emulsifiers
a)Non-ionic emulsifiers
Example: Sorbitan esters, Polyoxyethylene derivatives
•Non-ionic surfactants are effective over a pH range= 3-10
•Sorbitan esters are supplied commercially as Spans and are
mixtures of the partial esters of sorbitol and its mono- and
di-anhydrides with oleic acid.
• They are generally insoluble in water (low hydrophile–
lipophile balance (HLB) value) and are used as W/0
emulsifiers and as wetting agents.

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•Polyoxyethylene derivatives OR Polysorbates are
complex mixtures of partial esters of sorbitol and its
mono and di-anhydrides condensed with an
approximate number of moles of ethylene oxide.
They are supplied commercially as Tweens.
•The polysorbates are miscible with water, as
reflected in their higher HLB values, and are used as
emulsifying agents for o/w emulsions.
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b)Ionic emulsifiers
i. Anionic surfactants (negatively charged)
Example: various monovalent, polyvalent and
organic soaps e.g. Sodium lauryl sulfate (o/w), Sodium
stearate (o/w), Calcium oleate (w/o), Triethanolamine
(TEA) oleate (o/w).
Anionic surfactants require pH greater than 8
ii. Cationic surfactant (positively charged)
Example: benzalkonium chloride (bactericidal
properties)
Cationic surfactants are effective over pH= 3-7

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3) others: Finely divided solids
•Finely divided solid particles, which are adsorbed at the
interface between two immiscible liquid phases and form a
film of particles around the dispersed globules.
•Example: Colloidal clays, silicon dioxide, bentonite,
magnesium hydroxide, and aluminum hydroxide.
•Particles adsorb on oil-water interface and prevents
coalescence
•Emulsion type is based on preferential affinity of emulsifier
either with oil or water phase.
•Present better protection from microbes due to particle
nature.
•Colloidal aluminum and magnesium hydroxide for internal
preparations

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Methods of preparation of emulsions
•In the small-scale extemporaneous preparation of emulsions,
three (3) methods may be used:
i.Continental or Dry gum method
ii.English or Wet gum method
iii.Bottle or Forbes bottle method.
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I. Continental or Dry gum method
•The method is also referred to as the 4:2:1
(Oil-Water-Gum).
In this method:
1.The acacia or O/W emulsifier is triturated with the oil in a dry porcelain
mortar, until mixed. A rough surface should be used, for good grinding to
reduce the globules size.
2.Then the two parts of water are added all at once.
3.The mixture triturated immediately, rapidly and continuously until the primary
emulsion is formed. -Creamy white and produces a crackling sound.
4.Other liquid ingredients that are soluble in the external phase may then be
added.
5.Solid substances such as preservatives, stabilizers colorants, and any flavoring
material usually dissolved in a water then added to an emulsion.
6.Any substances that may interfere with the stability of emulsion (e.g. alcohol)
may added at the end.
7.When all necessary agents have been added, the emulsion is transferred to a
graduating cylinder and made to volume with water.

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ii. English or Wet gum method
The same proportion of water, gum and oil is used but the order of
mixing is different.
In this method:
1. Triturating of emulsifier (acacia) with water in a mortar.
2. The oil then is added slowly in portions.
3. The mixture is triturated to emulsify the oil.
4. The mixture is thoroughly mixed for several minutes to ensure
uniformity of the emulsion.
5. Then, as with the continental or dry gum method, the other
formulating materials are added.
6. The emulsion is then transferred to a graduating cylinder and
brought to volume with water.

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iii. Bottle or Forbes bottle method
It is used for volatile oils or oleaginous substances of low viscosity. (2:2:1)
1. The emulsifier (powder acacia) is placed in a dry bottle.
2. Two parts of oil then added.
3. The bottle is then shaken in a caped container.
4. A water is then added in portions.
5. When a primary emulsion is formed the other ingredients is added.
It is not suitable for viscous oils.
6. When all of the water has been added, the primary emulsion thus
formed may be diluted to the proper volume with water or an aqueous solution
of other formulating agents.
 When the intended dispersed phase is a mixture of fixed oil and volatile
oil, the dry gum method is generally employed.

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Methods of preparation of emulsions- SUMMARY

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AUXILIARY METHOD:
•To increase the quality of emulsion prepared by any of
the pervious methods:
The emulsion is passed through a hand homogenizer.
The emulsion is forced to pass through a very small
orifice which reduces the globules of the internal phase
to about 5 µm.

Stability of emulsions
•One of the most important characteristics of emulsions is their
inherent instability.
•Even though the dispersed drops are small, gravity exerts a
measurable force on them and over time they coalesce to form larger
drops which tend to either settle to the bottom or rise to the top of
the mixture. This process ultimately causes the internal and external
phases to separate into the two original components.
•Depending on how the emulsion is formulated and the physical
environment to which it is exposed, this separation may take minutes
or months.
•The stability of a pharmaceutical emulsion is characterized by:
the absence of coalescence of the internal phase,
absence of creaming, and
maintenance of elegance with respect to appearance, odor, color,
and other physical properties.

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STABILITY OF EMULSIONS
•The instability of pharmaceutical emulsions may
be classified as follows:
a) Creaming
b) Cracking and breaking
c) Phase inversion
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Instability of emulsions
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a) Creaming
“Concentration or aggregation of the globules of the
dispersed phase at the top or bottom of the system.”
•Depending upon the density of the continuous phase
relative to that of the dispersed phase, creaming can be:
UPWARD creaming- If dispersed phase is less dense than the
continuous phase (o/w)
DOWNWARD creaming (Sedimentation)- If dispersed phase is more
dense than the continuous phase (w/o)
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Rate of creaming:
•It depends upon the factors present in Stoke’s equation:
v =
??????
??????
(pi−pe)g
18η

Where,
V = rate of sedimentation
D = diameter of particles
p = density of internal phase and external phase
g = gravitational constant
η = viscosity of medium

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•Hence, in order to increase the stability of an emulsion
according to the Stoke’s equation:
globule or particle size should be Reduced (Homogenization)
density difference between the internal and external phases
should be Minimal,
viscosity of the external should be reasonably High.
•Creaming increases the risk of coalescence of globules of
the internal phase which then leads to the separation of
that phase into a layer….
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b) Cracking and breaking
“Separation of internal phase from emulsion is called
breaking and the emulsion is said as being cracked or broken.”

•The breaking or phase separation of emulsion occurs
because the protective sheath around the dispersed phase
globules no longer exists.
•Cracked or broken emulsion can not be reestablished on
simple agitation and additional emulsifying agents and
reprocessing (through appropriate machinery) is required
to reproduce the emulsion.
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CREAMING CRACKING
•Concentration or aggregation of the
globules of the dispersed phase at
the top or bottom of the system is
referred as creaming
•Separation of internal phase from
emulsion is called breaking or
cracking
•Reversible process •Irreversible process
•Reform emulsion on shaking •Do not form emulsion on shaking
•Globules of dispersed phase still
surrounded by protective sheath of
emulsifying agent
•Film of emulsifying agents
surrounding the particles no longer
exists

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c) Phase inversion
“Change of emulsion type from o/w to w/o and vice versa.”
•Phase inversion can be brought about by:
i.By adding electrolytes
ii.By changing phase volume ratio
i. By adding electrolytes
If sufficient amount of electrolyte is added, salting out can
occur, which may invert emulsion from o/w to w/o.
e.g. when CaCl
2 is added to o/w emulsion containing Na-stearate
as emulgent, it can invert the emulsion from o/w to w/o due to
formation of Ca-stearate
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ii.By changing phase volume ratio
Phase volume ratio is the relative volume of the internal and
external phase.
As the internal phase concentration of an emulsion increases,
there is an increase in viscosity of an emulsion to certain point
after which it decreases. At this point inversion occurs.
The concentration of the internal phase above which the
emulsifier can not produce a stable emulsion of desired type is
called Critical point.
Generally, a phase volume ratio of 50/50 results in most stable
emulsion.
However, a general emulsion may be prepared without inversion
with as much as 75% of volume of the internal phase.

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PHASE INVERSION- BY CHANGING PHASE VOLUME RATIO
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•The procedure of phase inversion is sometimes used in the
preparation of commercial emulsions, and it is the principle of the
continental method used in compounding practice.
•When controlled properly during the preparation of an emulsion,
phase inversion often results in a finer product.

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Instability types of emulsions

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Preservation from microorganisms
•Prevention from microbial
contamination is necessary
particularly in systems with high
water content and natural emulsifiers
like gums, which ultimately leads to
color and odor change, hydrolysis, pH
change and eventually the breaking
of emulsion.

Other factors to be considered related to emulsion stability
Commonly used antimicrobial
preservatives:
Parahydroxybenzoates (methyl &
propyl parabens)
organic acids (benzoic acid)
organic mercurials (phenyl mercuric
acetate)
quaternary ammonium compounds
(cetrimide)
cresol derivatives (chlorocresol),
miscellaneous agents (sodium
benzoate, chloroform)

Prevention from oxidation
Oxidation occurs due to atmospheric oxygen and
effects of microbial enzymes, which ultimately leads
to oxidative changes i.e. spoilage and rancidity of
natural oils in emulsified systems.
Commonly used anti-oxidants e.g.
Alkyl gallates
Butylated hydroxyanisole (BHA)
Butylated hydroxytoluene (BHT)
Tocopherols (Vitamin E)
OTHER FACTORS TO BE CONSIDERED RELATED TO EMULSION
STABILITY
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Assessment of stability of emulsions
•Emulsion stability can be assessed by:
Determination of Rate of creaming
Time dependent changes in size distribution of globules
Coulter counting
Turbidi-metric analysis
Temperature tests

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Examples of oral emulsions
1. Mineral oil emulsion- as a lubricating cathartic
2. Simethicone Emulsion- used as a anti-foaming agent for the relief of
painful symptoms of excessive gas in the gastrointestinal tract.
3. Castor oil emulsion- used as a laxative and in preparation of the
colon for radiography and endoscopic examination.
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Applications of emulsion
The pharmaceutical applications of emulsions include:
Administration of orally unpleasant tasting drugs (Vitamins A, D, E, K)
Formulation of oil soluble as well as water soluble drugs in single dosage
form
Diagnostic application (radio-opaque emulsions in x-ray examination)
IV administration of oils and fats in case of patients who are unable to
ingest oral feed (intralipid, lipofundin)
Externally applied pharmaceuticals and Cosmetic preparations (creams,
lotions)
As aerosol products (foams)
Depot preparations (contraceptives)
Better absorbed (heparin) and better stabilized emulsion dosage form
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References:
- Ansel’s Pharmaceutical Dosage Forms and Drug Delivery
Systems (9
th
Edition)
- Martin’s Physical Pharmacy and Pharmaceutical Sciences
(6
th
Edition)

1/6/2021 Physical Pharmacy-I 92

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