This document discusses emulsions and self-emulsifying drug delivery systems (SEDDS). It defines emulsions as mixtures of two immiscible liquids stabilized by an emulsifying agent. The main types of emulsions described are oil-in-water, water-in-oil, multiple emulsions, and microemulsions. SEDDS are defined as isotropic mixtures of oils, surfactants, and co-solvents/co-surfactants that spontaneously form emulsions when exposed to aqueous media and can improve drug solubility and bioavailability. Key factors in developing SEDDS like choice of oils, surfactants, and evaluation methods are also summarized.

1. Group number: 02
Course: Physical Pharmacy
Course Code: 311
EMULSIONS
Presented by
(Dr) Kahnu Charan Panigrahi
Asst. Professor, Research Scholar,
Roland Institute of Pharmaceutical Sciences,
(Affiliated to BPUT)
Web of Science Researcher ID: AAK-3095-2020
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2. INTRODUCTION
• An emulsion is a mixture of two or more liquids that
are normally immiscible
• Emulsion should be considered when both the
dispersed and the continuous phase are liquids.
1-Oil in water emulsions
2- Water in oil emulsions
3 Multiple emulsions (O/W/O) or (W/O/W)
4 Microemulsions.
TYPES OF EMULSIONS:
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3. MULTIPLE EMULSIONS:
• Multiple emulsions are the emulsion system in which
the dispersed phase contain smaller droplets that have
the same composition as the external phase.
• The multiple emulsions are also considered to be of two
types:
Oil-in-Water-in-Oil (O/W/O) emulsion system
Water-in-Oil-In-Water (W/O/W) emulsion system
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5. MICROEMULSIONS:
• Clear, stable, liquid mixtures of oil, water and surfactant,
frequently in combination with a co-surfactant.
• The two basic types of Microemulsions are (o/w) and (w/o).
Unlike the common macro emulsion in that:
1 Appear as clear transparent solution.
2 Diameter of internal phase droplets ranged between 10-
200nm.
3 Thermodynamically stable.
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6. DETECTION TESTS:
 Dilution test:Based on the solubility of external phase
of emulsion.
- o/w emulsion can be diluted with water.
- w/o emulsion can be diluted with oil.
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 Conductivity Test: Water is good conductor of electricity
whereas oil is non- conductor. Therefore, continuous phase of water
runs electricity more than continuous phase of oil.

7. Dye-Solubility Test:
when an emulsion is mixed with a water soluble dye and
observed under the microscope.
if the continuous phase appears red, then it means the emulsion
is o/w type as water is the external phase,
if the scattered globules appear red and continuous phase
colorless, then it is w/o type.
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Fluorescence test:
Oils give fluorescence.
Under UV light, while water doesn’t.
Therefore, O/W emulsion shows spotty pattern while W/O
emulsion fluoresces completely.

8. EMULSION INSTABILITY:
The instability of pharmaceutical emulsions may be classified as
following:
 Flocculation and creaming
 Coalescence and breaking
 Phase inversion
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9.  FLOCCULATION:
The small spheres of oil join together to form clumps or flocks which
rise or settle in the emulsion more rapidly than individual particles.
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 CREAMING:
It is the concentration of the floccules of the internal phase form
upward or downward layer according to the density of internal
phase. Stokesequationincludedthe factorsthat affectthe creaming
process:



18
)
(
dim
2
g
d
rate
entation
Se l
s 

Where d is the particle diameter
s, l are densities of a particle and liquid respectively
g is the acceleration of gravity.
 is the viscosity of the medium.

10.  COALESCENCE:
• Itis the process by which emulsified particlesmerge with each to
form largeparticles.
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 BREAKING:
• Due to coalescence and creaming combined,the oil separates
completely from waterso that it floats at the top in a single,
continuouslayer.

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Cracking of emulsion can be due to:
1-addition of an incompatible emulsifying agent:
e.g. monovalent soap + divalent soap
2-chemical or microbial decomposition of emulsifying agent:
e.g. alkali soap decompose by acid.
3-exposure to increased or reduced temperature
4-addition of common solvent.

12. DIFFERENCE BETWEEN CREAMING AND CRACKING
CREAMING BREAKING
 Formation of upward and
downward layer.
 Separation of emulsion to
upward oily layer and
downward aqueous layer.
 Reversible.  Irreversible.
 Partial or no coalescence.  Complete fusion.
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13.  PHASE INVERSION:
 In phase inversion o/w type emulsions changes into w/o type
and vice versa.
 It is a physical instability.
It may be brought about by:
 the addition of an electrolyte e.g. addition of calcium chloride
into o/w emulsion formed by sodium stearate can be inverted to
w/o.
 by changing the phase volume ratio.
 by temperature changes.
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14. Phase inversion can be minimized by:
ousing the proper emulsified agent in adequate
concentration.
okeeping the concentration of dispersed phase below 74
%.(ideally 30-60)
ostoring the emulsion in a cool place.
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15. When two immiscible liquids are agitated together so that one of
the liquids is dispersed as small droplets in the other.
To prevent coalescence between globules, it is necessary to use
emulsifying agent.
There are three types of films:
Monomolecular Films.
Multimolecular Films.
Solid Particle Films.
MECHANISM OF EMULSIFICATION
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16. 1. Monomolecular Film:
Coherent monomolecular film.
Flexible film formed.
Can prepare O/W or W/O emulsion.
Lower surface tension and increase stability of emulsions.
Examples:
Potassium Laurate
Polyoxyethylene sorbitan monooleate
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17. 2. Multi-molecular Film:
o Strong rigid film formed.
o mostly by the hydrocolloid.
o Produce o/w emulsion.
o Have low effect on surface tension
o Formed by viscosity enhancement
Examples:
o Acacia
o Gelatin
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18. 3. Solid Particle Film:
o Film formed by solid particles that are small in size compared to
the droplet of the dispersed phase.
o Can form o/w and w/o emulsions.
o Particles must be wetted by both phases in order to remain
at the interface and form stable film.
Examples:
o Bentonite
o Graphite
o Magnesium Hydroxide
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19. METHODS OF PREPARATION:
 Continental or Dry Gum Method:
• Emulsifier is triturated with the oil in perfectly dry porcelain mortar
and water is added
• Triturate immediately, rapidly and continuously (until get a clicking
sound and thick white cream is formed, this is primary emulsion.
• oil:water:gum is 4:2:1
• The remaining quantity of water is slowly added to form the final
emulsion
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20.  English or Wet Gum Method:
• Triturate gum with water in a mortar to form a mucilage.
• Oil is added slowly in portions the mixture is triturated.
• After adding all of the oil, thoroughly mixed for several minute to
form the primary emulsion.
• oil:water:gum is 4:2:1
• Once the primary emulsion has been formed remaining quantity of
water is added to make the final emulsion.
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21. Bottle or Forbes Bottle Method:
• It is extemporaneous preparation for volatile oils or oil with low
viscosity.
• gum + oil (dry bottle)
• water (volume equal to oil) is added in same amount as oil with
vigorous shakeing to form primary emulsion.
• Ratio of oil:water:gum is (4:4:2)
• Remaining quantity of water is added to make the final emulsion.
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22. QUALITY CONTROL TEST OF
EMULSION
• Appearance
• Clarity testing
• pH value
• Viscosity
• Rheology
• Drug content uniformity
• Globule size distribution
• Densities of phases
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23. WHAT ARE SEDDS ?
• SEDDS or self-emulsifying formulations (SEF) are
defined as Isotropic mixtures of natural or synthetic oils,
surfactants and co-solvents/co-surfactants. (Porter C.J. et
al 2008)
• Self-emulsification is a term used to describe
emulsification which occurs with little or no input of
energy. The process may be spontaneous or may
require low levels of shear.
• These systems form fine oil-in-water (o/w) emulsions or
micro emulsions (SMEDDS) or nano emulsion
(SNEDDS) upon mild agitation followed by dilution in
aqueous media, such as gastrointestinal (GI) fluids.
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24. FORMULATION OF SEDDS
• DRUG
• OILS
• SURFACTANT
• CO SURFACTANT
• CO SOLVENT
24
CO-
SURFACTANT
DRUG
OIL
SURFACTANT
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Increasing hydrophilic content →
OIL SEDDS SMEDDS SMEDDS OIL FREE
TYPE I TYPE II TYPE IIIA TYPE IIIB TYPE IV
Typical composition (%)
Triglycerides or mixed
glycerides
100 40–80 40–80 <20 -
Water-insoluble
surfactants (HLB<12)
- 20–60 - - 0–20
Water-soluble
surfactants (HLB>12)
- - 20–40 20–50 30-80
Hydrophilic co-solvents
- - 0–40 20–50 0–50
Particle size of
dispersion (nm)
Coarse 100–250 100–250 50–100 <50
Significance of aqueous
dilution Limited
importance
Solvent capacity
unaffected
Some loss of
solvent
capacity
Significant phase
changes and
potential loss of
solvent capacity
Significant phase
changes and
potential loss of
solvent capacity
Significance of
digestibility
Crucial
requirement
Not crucial but
likely to occur
Not crucial
but may be
inhibited
Not required Not required
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TABLE – 1 LIPID FORMULATION CLASSIFICATION SYSTEM

26. OILS
• Oils can solubilise the lipophilic drug in a specific amount and facilitate
self-emulsification.
• Increase the fraction of lipophilic drug transported via the intestinal
lymphatic system, thereby increasing absorption from the GI tract.
• Long-chain triglyceride and medium-chain triglyceride oils with different
degrees of saturation have been used in the design of SEDDSs. (Charman
SA et al 1992)
e.g. Tocopherol, Corn oil, Olive oil, Oleic acid, Sesame oil, Hydrogenated
vegetable oils, Soyabean oil, Peanut oil, Beeswax
26
DRUG
Drugs which have high lipophillicity, low melting point, low bioavailability and
poor solubility in water are selected for SEDDS.
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27. SURFACTANT
Surfactants with high hydrophilic Lipophilic Balance (HLB) values are used
in formulation of SEDDS.
e.g.Tween, Labrasol, Labrafac CM 10, Cremophore etc.
27
CO SOLVENTS/CO SURFACTANT
Organic solvents suitable for oral administration may help to dissolve
large amounts of either the hydrophilic surfactant or the drug in the lipid
base and can act as co-surfactant .
e.g. ethanol, propylene glycol (PG) polyethylene glycol (PEG), etc
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28. EVALUATION OF SEDDS
• DISPERSABILITY TEST
• REFRACTIVE INDEX AND PERCENT TRANMISSION
• GLOBULE SIZE MEASUREMENT
• POLYDISPERSIBILITY INDEX DETERMINATION
• ZETA POTENTIAL MEASUREMENT
• DRUG CONTENT
• IN VITRO DRUG DISSOLUTION STUDY
• BIO-ANALYTICAL STUDY
• STABILITY STUDIES
28
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29. ADVANTAGES
• Improvement in oral bioavailability
• Ease of manufacture and scale-up
• Reduction in inter-subject and intra-subject variability
and food effects:
• Ability to deliver peptides that are prone to enzymatic
hydrolysis in GI.
• No influence of lipid digestion process as found in other
LDDS.
• Increased drug loading capacity
• Protection of sensitive drug substances.
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