Emulsion Types Methods Applications Advantages Disadvantage Preperations

2.  The term "Disperse System" refers to a
system in which one substance (the
dispersed phase) is distributed, in discrete
units, throughout a second substance (the
continuous phase or vehicle).
 Each phase can exist in solid, liquid, or
gaseous state .

3.  Molecular dispersions (less than 1 nm)
 particles invisible in electron microscope
 Pass through semi-permeable membranes
and filter paper .
 - Particles do not settle down on standing
 Undergo rapid diffusion
e.g. oxygen molecules , glucose

4.  Colloidal dispersions (1 nm - o.5 um)
 Particles , can be detected by electron
microscope.
 Pass through filter paper but not pass
through semi- permeable membrane.
 Particles made to settle by centrifugation
Diffuse very slowly
 E.g. colloidal silver sols, natural and
synthetic polymers.

5.  Coarse dispersions (> 0.5 um)
 Particles are visible under ordinary
microscope
 Do not pass through filter paper or semi-
permeable membrane.
 Particles settle down under gravity
 Do not diffuse
 E.g. emulsions, suspensions,

6. Definition:
 An emulsion is a system comprising two
immiscible liquid phases, one of which is
dispersed throughout the other in the form of
fine droplets. A third component, the
emulsifying agent ,is necessary to stabilize
the emulsion.
 Emulsions are thermodynamically unstable.
 Stabilized by adding emulsifying agents.
 Lecithin is emulsifying agent present in egg
yolk.
.

7.  Example of emulsions are:
 Milk ,mayonnaise ,skin creams, ointments,
moisturizing lotions ,vitamin drops, etc.
 Milk is naturally occurring emulsion of fats
and water.

8. Dispersed phase:
 The phase that is present as fine droplets
is called the dispersed phase or internal/
discontinous phase.
Continuous phase:
 The phase in which the droplets are
suspended is the continuous phase or
external phase.

9. 1.Macro emulsions:
 Oil in water emulsions:(o/w)
 Water in oil emulsions (w/o)
2.Multiple emulsions(o/w/o),(w/o/w)
3.Micro emulsions
Macro emulsions:
Particle size of dispersed phase ranges from 0.1 to 10 micrometer.
Oil in water emulsions:
In this type of emulsion oil is dispersed phase and water is the
continuous medium.
e.g. milk, cream
Most emulsions designed for oral administration are of o/w type.

10.  Water in oil emulsions:
 In this type of emulsion water is the dispersed phase and oil
is the continuous phase.
 e.g. butter, cold creams, oily calamine lotion.
 Multiple emulsions:
 Multiple emulsions are complicated emulsion system in which
oil droplet enclosing a water droplet may be suspended in
water to form a water -in -oil –in- water emulsion.
 These type of emulsions are specially developed to delay the
release of ingredients from drug.
 w/o/w
 O/w/o

12.  Micro emulsions are homogeneous ,clear,
liquid mixture of oil, water, surfactants and co-
surfactants ,which have very smaller droplet
size(5nm to 140nm) than coarse emulsions.
 Droplets of this size cannot refract light and as
result are invisible to the naked eye.
 They are thermodynamically stable.
 They are stable for relatively long periods
 They form spontaneously when components are
mixed in the appropriate ratios but coarse
emulsion need vigorous shaking.

13.  The type of micro emulsion formed is determinedby
the nature of the surfactant, in particular its
geometry, and relative quantities of oil and water.
 Surfactants are compounds that lower the surface
tension between liquids, btw gases and liquid, or
between a liquid and a solid. Its one end attracted to
water and another end holds oil part.
 Co surfactants are also added which helps to dissolve
large amount of hydrophilic surfactants or hydrophobic
drugs in liquid phase.

15.  o/w emulsion
 w/o emulsion
 Bi –continuous emulsion

16.  Long shelf life
 Easy preparation
 Improved bioavailability
 Increase rate of absorption
 Helps in solubilizing lipophilic drugs.

17.  They require larger amounts of surfactant
and co-surfactants for formulation..

18.  applications in transdermal and dermal
delivery
 Applications in oral drug delivery
 Applications in parenteral drug delivery
 Applications in ocular drug delivery

19. Final preparation of both emulsions (o/w or
w/o) looks the same in appearance with
naked eyes, therefore certain tests are
required to differentiate between them.
 Dilution test
 Conductivity test
 Dye solubility test
 cobalt chloride test
 Fluorescent test
Creaming test

20. 1.Dilution test:(miscibility test)
In this test the emulsion is diluted either
with oil or water. If the emulsion is o/w
type and it is diluted with water, it will
remain stable as water is the dispersion
medium"
but if it is diluted with oil, the emulsion
will break as oil and water are not miscible
with each other. Oil in water emulsion can
easily be diluted with an aqueous solvent
whereas water in oil emulsion can be
diluted with a oily liquid.

21. 2.Conductivity Test:
 The basic principle of this test is that
water is a good conductor of electricity.
Therefore in case of o/w emulsion, this
test will be positive as water is the
external phase. In this test, an assembly
is used in which a pair of electrodes
connected to an electric bulb is dipped
into an emulsion. If the emulsion is o/w
type, the electric bulb glows.

23. 3.Dye Solubility Test:(staining test)
In this test an emulsion is mixed with a water
soluble dye (amaranth) and observed under the
microscope. If the continuous phase appears
red, it means that the emulsion is o/w type as
water is in the external phase and the dye will
dissolve in it to give color. If the scattered
globules appear red and continuous phase
colorless, then it is w/o type. Similarly if an oil
soluble dye (Scarlet red C or Sudan III) is added
to an emulsion and the continuous phase
appears red, then it is w/o emulsion.

25. 4.Cobalt Chloride Test:
 When a filter paper soaked in cobalt chloride
solution(which is water soluble) is dipped in
to an o/w emulsion and dried,as humidity
increases . it turns from sky blue(anhydrous
form) to pink, indicating that the emulsion is
o/w type.
 COCL2 is used to test the presence of water.
5.Fluorescence Test:
 If an emulsion on exposure to ultra-violet
radiations oil shows continuous fluorescence
under microscope, then it is w/o type and if
it shows only spotty fluorescence, then it is
o/w type.

26. 6.Creaming test:
Creaming results in a lack of
uniformity of drug distribution.
Therefore, the emulsion should be shaken
thoroughly before use
. • Creaming is of two types,
 upward creaming and downward creaming
Upward creaming, is due to the dispersed
phase is less dense than the continuous
phase. This is normally observed in o/w
emulsions. The velocity of sedimentation
becomes negative.
• Downward creaming occurs if the dispersed
phase is heavier than the continuous phase.
Due to gravitational pull, the globules settle
down. This is normally observed in w/o
emulsions.

27.  Emulsification.
“The process of mixing two
immiscible liquids by adding emulsifying agents is
known as emulsification.”
 There is no universal theory of emulsification
because emulsion can be prepared by several
different types of emulsifiers to a stable product
 When a liquid is broken into small droplets, the
surface area of droplets increases ,resulting in
surface free energy and the system become
unstable with the result two phases are
separated.
 Emulsifying agents are used to stabilize the
emulsion system.

28. following theories are most famous.
 interfacial tension theory
 The Viscosity theory
 Oriented wedge theory
 Interfacial film theory

29.  This theory explains stability of
emulsions. According to this theory, in
emulsification when tension exists at the
surface of two immiscible liquids
emulsification will be difficult.
 Emulsifying agent on addition into the
system, lowers down the surface tension
and hence prevent dispersed globules to
coalesce and globules will remain
separated therefore emulsion is
stabilized.

31.  Surface tension
 It is the attractive forces which exist at
surfaces exposed to air.
 Interfacial tension
 It is the attractive forces which exist at
liquid surface exposed to another liquid
surfaces.

32.  Surfactants also reduce larger globules
into smaller ones as smaller globules have
lesser tendency to reunite ,so the system
is stabilized.
 it reduces repellent force between the
liquids and diminishing each liquid’s
attraction for its own molecule.

33.  The viscosity plays an important role in both
theoretical and practical consideration of
emulsion system. according to this theory the
greater the viscosity of emulsion greater will
be its stability but this theory is not perfectly
explained the stability of all emulsions. e.g
milk is most stable if less viscous.
 Viscosity theory explain other facts such as
very fine emulsions have greater viscosity and
stability than the coarse emulsion.

34.  This theory based on the presumption
that certain emulsifying agent orient
themselves in that liquid phase of
emulsion in which it is more soluble and
will be embedded more in this phase than
other phase.
 An emulsifying agents having greater
hydrophilic character will promotes o/w
emulsion.
 A w/o results when emulsifying agent is
more hydrophobic than hydrophilic .

35. in this theory mono molecular layers of
emulsifying agents are curved around a
droplet of the internal phase of the
emulsion.
Generally ,emulsifying agent having
greater hydrophilic character than
hydrophobic will promote an o/w
emulsion, and w/o emulsion results from
use of emulsifying agent that is more
hydrophobic than hydrophilic character.

36. According to this theory a film of emulsifying
agent prevents the contact and coalescing of
the dispersed phase
Emulsifying agent forms a film by adsorbing
around the surface of droplets of internal
phase. This film prevents the contact and
reuniting of internal phase/dispersed phase.
The tougher and more pliable the film, the
greater the stability of the emulsion. The
type of emulsion is determined by degree of
stability of emulsifying agent in both phases.
if it is more soluble in aqueous phase ,the
emulsion will be oil in water and vice versa.

37.  Emulsifying agents are used to stabilize the
emulsion .These are substances of widely
different chemical nature.
 Emulsifying agent has both polar and non
polar types of portion which are soluble in
two phases and are wetted by both liquid
phases.
 According to Bancroft rule, the phase in
which emulsifying agent is more soluble
results in continuous phase. In o/w emulsion
emulsifying agents are more soluble in water
than in oil .in w/o emulsion emulsifying agent
are more soluble in oil than water.so it is
possible to convert one type of emulsion into
another.

38.  Each emulsifying agent has specific HLB
value (hydrophilic, lipophilic
Balance)which determines the emulsion
type.
 HLB system is applied for the selection of
emulsifying agents.
 Emulsifying agents used in pharmaceutical
products are tragacanth, sodium lauryl
sulfate, sodium dactyls sulfo succinate.
Etc.

39.  it should be inert ,non irritant, non toxic.
 It should be physically and chemically
stable.
 It should not impart any color, odor, or
taste to preparation.
 It should be able to produce and maintain
the required viscosity of the preparation.
 It should be able to reduce interfacial
tension between two immiscible liquid.

40.  It should be able to form film around the
globules and should prevent coalescence
of droplets of dispersed phase.
 It should be suitable for wide range of
liquid not for specific liquids.
 It should be stable in strong heat and
cooling
 It should be easily available and cheap.

41.  Natural emulgents
 Synthetic emulgents
Natural emulsifying agents from vegetable sources
a. Acacia b. Tragacanth c. Agar d. Pectin e. Starch
Natural emulsifying agents from animal sources
Gelatin b. Egg yolk c. Wool fat
Semi-synthetic polysaccharides a. Methyl cellulose b.
Sodium carboxymethyl cellulose
Synthetic emulsifying agents
a. Anionic b. Cationic c. Non-ionic

42.  Inorganic emulsifying agents /finely
divided solids
a. Milk of magnesia b. Magnesium oxide c.
Magnesium trisilicate d. Bentonite
Saponins
Alcohols
a.Cholesterol
b.Carbo waxes
c. Lecithin

43.  Acacia:- -
 Acacia (most common gum) is the best
emulsifying agent for extemporaneous
preparation of emulsions for internal use. –
 They are stable over a wide range of pH 2 to 10.
 - These emulsions usually have low viscosity
therefore creaming take place which can be
prevented by increasing viscosity of the medium
by incorporating tragacanth, agar or pectin along
with acacia.
 Tragacanth:- -
 It is rarely used as an emulsifying agent.
 - It produces very coarse & thick emulsions &
sometimes viscosity increases to much an extent
that pouring of the emulsion becomes problem.
 - It is used mainly as an emulsion stabilizer,
particularly in acacia emulsions. - A suitable
proportion is 1 part to 10 parts of acacia.

44.  Pectin:- -
Pectin is carbohydrate obtained from inner
part rind of citrus fruit & from the apple pulp
& guava. –
It acts as a emulsion stabilizer in acacia
emulsions.
A mucilage of pectin is first prepared before
adding it to the preparation.
To prevent clumping with water it should
previously wetted with alcohol, glycerol or
syrup.
 AGAR:- -
Agar is a dried extract from certain seaweeds.
- it forms a very coarse & viscous emulsion.
It was formerly used as an emulsion stabilizer
in liquid paraffin emulsions prepared with
acacia.

45.  Natural emulsifying agents from animal
sources
Gelatin:
obtained from boiling animal bones and
connective tissue. Gelatin emulsions are
prone to bacterial growth therefore
suitable preservative must be incorporated.
Emulsion become more fluid upon standing.
Lecithin:
this is phosholipids in nature and obtained
from egg yolk.
 It is generally used for the emulsification
of fish liver oils

46.  Wool Fat:- • Wool fat also called as
anhydrous lanolin •
 It is poorly absorbed in skin but with soft
paraffin or vegetable oils produce creams
that penetrate well & assist absorption of
medicaments. •
 It is used in W/O type of emulsion.

47.  Semi-synthetic polysaccharides:
Methyl Cellulose:-
• It is available methyl cellulose 20, methyl
cellulose 2500 & 4500 the numbers indicate
their viscosity in aq. solution.
. • It is soluble in hot water. • It is stable to pH
changes & alcohol but produces ppt in the
presence of large amounts of electrolytes.
Sodium Carboxymethyl Cellulose:
It is not used as true emulsifier
• It is used as an emulsion stabilizer in the
concentration of 0.5 to 1.0%.
It is soluble in cold water & hot water.

48.  Synthetic Emulsifing Agents or Surfactants
Anionic:-
 It is used good emulsifying agents for
those emulsions which are applicable for
external purpose. • various alkali soaps,
metallic soaps, sulphated alcohols &
sulphonates are used as emulsifying
agents.
 Sulphated salts, sodium lauryl sulphate is
commonly used as emulsifying agent in
topical preparation

49.  Cationic:-
 They are used emulsifying agent in O/W
type of emulsions.
 Quaternary ammonium compounds are
only group that extensively used
emulsifying agent.
 They show anti bacterial properties, so it
is used for disinfectant.
 It is not good emulgent when it used
singly but with alkali sulphates &
phosphates it produce good emulsions.
When combined with fatty alcohols it
shows greater stability.
 It is stable at pH range 3 to 7.

50.  • Non-Ionic:
Non-ionic surfactant are widely used in the
pharmaceutical emulsion.
These emulsions are stable over a wide
range of pH.
It’s not affected by addition of acids &
electrolytes.
The most commonly used surfactant are
glyceryl monostearate,
polyoxyethylene glycol esters & ethers &
sorbitan monopalmitate.

51.  SAPONINS
 Saponins are glycosides rarely used as
emulsifying agents.
 ALCOHOLS
 Cholesterol:- • A number of high molecular weight
alcohols are used.
They used as a stabilizer in emulsion preparation.
Cetyl alcohol, stearyl alcohol, glyceryl
monostearate included in this group.
Carbowaxes:-
They act as non-ionic emulsifying agents.
• They are used in the ointments & cream
preparations
Lecithin:- • Lecithin forms W/O type emulsion. •
It is rarely used as emulsifying agent Because
when exposed to light gets easily oxidised.

52.  The hydrophilic-lipophilic balance of a surfactant is a
measure of the degree to which it is hydrophilic or
lipophilic,
 Discovered by Griffin scientist in 1954.
 Each emulsifying agent has hydrophilic and
lipophilic portion.
 HLB ranges from 1-20
 Emulsifying agent with high HLB values i.e. 7 to
20 are hydrophilic and produce oil/w emulsion
& those with low HLB values i.e. 3 to 6 are
lipophilic in nature.
 Calculating HLB values by Griffin's method
HLB=20*(Mh/M)
Mh=molecular weight of hydrophilic groups
M=molecular weight of the whole molecule.

53.  The HLB of a number of poly hydric
alcohol ,fattyacids esters ,such as glyceryl
monostearate may be estimated by using
formula .
HLB=20(1-s/A)where,
s= Saponification number of the ester and
A= is the acid value of fatty acid.

54.  In sodium stearate ,-C17H35COONa,the
non polar hydrocarbon chain.
 C17H35 is the lipophilic group and the
carboxyl group
 ,-COONa is the hydrophilic portion.
 It is calculated for nonionic surfactants.
 If we need mixing of two unlike oils
together than use surfactants with HLB
value 1 to 3.

55.  Emulsifier with low HLB
An emulsifier having a low HLB number
indicates that the number of hydrophilic
groups present in the molecule is less and
it has a lipophilic character. For example,
spans generally have low HLB number and
they are also oil soluble. Because of their
oil soluble character, spans cause the oil
phase to predominate and form a w/o
emulsion.

56.  Emulsifier with high HLB
A higher HLB number indicate that the
emulsifier has a large number of
hydrophilic groups on the molecule and
therefore is more hydrophilic in character.
Tweens have higher HLB numbers and they
are also water soluble. Because of their
water soluble character, tweens will cause
the water phase to predominate and form
an o/w emulsion

60. Interfacial film in emulsion stabilization:
 When two immiscible liquids, e.g. liquid
paraffin/oil are shaken together ,a temporary
emulsion will be formed.
 The breakdown of of large globules into small
globules results in a large increase in the surface
area and surface free energy of system. Thus the
system is thermodynamically unstable results in
separation of dispersed and continuous phase.
 The adsorption of a surface active agent at the
globules interface will lower the o/w surface
tension and enhance the stability of system.

61.  If surface active agent/surfactant such as
sodium dodecyl sulfate is used, emulsion
on standing for short while will separate
out into its contituent phases. on the
other hand ,substances such as acacia,
which is not good emulsifying agent but
good emulsion stabilizer produce stable
emulsions. acacia forms a strong viscous
interfacial film around the globules.
 If the emulsifying agent is ionic ,then the
charged molecules of film will mutually
repel each other and with the result
stability of emulsion increased.

62.  However emulsifying agents with non
ionic nature are frequently used. mixture
of sorbitan monooleate and
polyoxyethylene sorbitan esters
(polysorbate 80) have good emulsifying
properties.
 Non ionic surfactants are widely used in
the production of stable emulsions and
have advantage over ionic surfactants of
being less toxic and less sensitive to
electrolytes and pH variation.

64.  Multimolecular adsorption as emulsion
stabilizers:
 A number of hydrophilic colloids are used as
emulsifying agent in pharmaceutical science.
 These includes protein(gelatin, casein)and
polysaccharides(acacia, cellulose derivatives
and alginates.
 Hydrophilic colloids don’t lower surface
tension but form multimolecular adsorption
at the oil/ water interface. They have low
effect on the surface tension. Their main
function as emulsion stabilizers is by making
coherent multi-molecular film. This film is
strong and resists the coalescence.

65.  They have, also, an auxiliary effect by
increasing the viscosity of dispersion
medium.
Most of the hydrophilic colloids form oil-
in-water emulsions.
Some of them can provide electrostatic
repulsion like acacia, which contains
Arabic acid and proteins (COOH and NH3)

66.  Solid particle in emulsion stabilization:
 Finely divided solid particles are adsorbed
at the surface of emulsion droplet to
stabilize them. Those particles are wetted
by both oil and water (but not dissolved)
and the concentration of these particles
form a particulate film that prevent the
coalescence.

67.  Aluminium and magnesium hydroxides and
clays such as bentonite are wetted by
water and thus stabilize as o/w emulsion.
 Carbon black and talc are more readily
wetted by oils and stabilize w/o emulsion.

68.  A stable emulsion may be defined as a
system in which the globules retain their
initial character and remain uniformly
distributed throughout the continuous
phase.
 Separation of an emulsion into its
constituent phases is termed cracking or
breaking .it follows that any agent that
will destroy the interfacial film will crack
the emulsion.

69.  Some of the factors that cause an
emulsion to crack are as follows:
 Addition of a chemical that is
incompatible with emulsifying agent, thus
destroying its emulsifying ability.
 Bacterial growth :protein materials are
excellent media for bacterial growth.
 Temperature change –protein emulsifying
agents may be denatured and solubility
character of non-ionic surfactant change
with rise in temperature. heating above
70C destroys most emulsion. freezing
temperature will also crack the emulsion.

70.  Ways in which an emulsion may show instability
are as follows:
 Flocculation/aggregation
 Phase inversion
 creaming:
 Breaking or cracking
 coalescence
Flocculation:
 On standing, neighboring globules of the
dispersed phase come closer to each other and
form colonies in the continuous phase. However,
the droplets may be redispersed by shaking and
may lead to coalescence.
 The extent of flocculation depends on: -
dispersed Globules size.–
 Charge on globules surface –
 Viscosity of external medium (contineous phase)

72.  Creaming:
On standing, creaming is the concentration of
globules at the top or bottom of emulsion (due to
density differences between the two phases).
Globules move either upwards (o/w emulsion) or
sink downwards (w/o emulsion) leading to
creaming. It can be observed by a difference in
color shade of both layers, and in both cases,
emulsion can be easily redispersed by shaking.
 As in flocculation, droplets do not coalesce and
can be redispersed by gentle shaking. Creaming is
however undesirable pharmaceutically because:
 1. Increased possibility of coalescence of droplets
 2. Creamed emulsion is inelegant in appearance
 3. Risk of incorrect dose if not shaken enough.
 The rate of creaming is governed by stoke’s law
i.e

73. V=velocity of creaming
r=radius of droplet
g= acceleration due to
gravity.
d1=density of dispersed
phase.
d2=density of continuous
medium.
u=viscosity of continuous phase.

74.  Factors affecting creaming are best
described by Stoke’s law. Creaming can
be reduced by:
 1. Reducing globule size by
homogenization
 2. Increasing viscosity of dispersion
medium
 3. Reducing the difference in density.

75.  Coalescence:
 Is followed by the creaming stage wherein
droplets merge forming larger droplets. This
process continues until the emulsion breaks
(cracks). In this process, the emulsifier film
around globules is destroyed to a certain
extent.
 Coalescence is observed due to: -
 Insufficient amount of the emulsifying agent.
- Incompatibilities between emulsifiers.
 The major fact preventing coalescence is the
mechanical strength of the interfacial film.

76. Cracking (breaking):
 It is indicated by complete separation of
oil and the aqueous phase.
 It is an irreversible process that simple
mixing fails to resuspend globules into a
uniform emulsion.
 In breaking, the protective sheath around
globules is completely destroyed.

77. Cracking (breaking) Factors that cause
emulsion cracking
The addition of a chemical that is
incompatible with the emulsifier e.g., addition
of a cationic surfactant to an emulsion
stabilized with an anionic surfactant;
addition of electrolytes to emulsion stabilized
with opposite ionic surfactants.
o Bacterial growth: Protein and polysaccharide
emulsifiers are excellent media for bacterial
growth
. o Temperature fluctuations: Protein
emulsifiers may be denatured and the
solubility of non-ionic surfactants change with
a rise in temperature (heating above 70C
destroys most emulsifiers).
Freezing will also crack emulsion because the
ice crystals formed disrupt the interfacial film
around droplets.

78.  Phase inversion:
 This involves the change of emulsion type
from o/w to w/o and vice versa. o When we
intend to prepare an o/w emulsion and if the
final emulsion turns out to be w/o, it can be
termed as a sign of instability.

79.  Phase inversion
 Reasons of phase inversion:
 • Increasing the dispersed phase concentration above the
accepted value.t he accepted range is 30-60%
 Adding substances that alter the solubility of the emulsifier
(e.g precipitation of hydrophilic colloids like acacia in the
presence of alcohol).
 • Suppression of ionization for ionic surfactants by adding
substances with opposite charges (e.g., addition of CaCl2
into o/w emulsion formed by sodium stearate can be
inverted to w/o)
 Temperature of the system
Emulsions stabilized with nonionic emulsifying agents such as
the polysorbates may invert on being heated.this is due to the
breaking of the hydrogen bonds responsible for hydrophilc
characteristics of polysorbate,its HLB value is thus altered and
the emulsion inverts.

80.  The addition of an electrolyte to anionic and
cationic surfactants may suppress their
ionization due to the common ion effect,
thus a w/o emulsion may result even though
normally an o/w emulsion would be
produced.
 e.g. pharmacopeial white liniment is formed
from turpentine oil, ammonium oleate
,ammonium chloride and water. with
ammonium oleate as emulsifying agent, an
o/w emulsion would be expected but the
suppression of ionization of the ammonium
oleate by ammonium chloride(the common
ion effect) and relatively large volume of
turpentine oil produce a w/o emulsion.

82.  Oral, and topical administration of oils and oil-
soluble drugs. –
 The unpleasant taste or odor can be masked by
emulsification
 The absorption and penetration of medicament
are enhanced by emulsification
 Intramuscular injections of water-soluble drugs
or vaccine to provide slow release
 The use of sterile stable i.v. emulsion containing
fats, carbohydrates and vitamins as a potential
nutrition for bed ridden patients.
 Emulsion provide protection to drug which are
susceptible to oxidation.((add more points)