aqueous one known as a direct emulsion. Stabilization of O/W emulsion is often performed with hydrophilic-hydrophobic particles. The hydrophilic end of the emulsifier molecule has an affinity for water, and the hydrophobic end is drawn to the fat/oil. Vigorously mixing the emulsifier with the water and oil creates a stable emulsion. For example, milk is oil in the water type of emulsion. In this mixture, fat globules are dispersed in the water. Emulsion water in oil (W/O) is composed of an aqueous phase dispersed in the oil phase. A water-in-oil emulsion is much fattier than a direct emulsion. Margarine is a water-in-oil emulsion. Other emulsions, such as oil in water in oil, or water in oil in water, exist as well. Blood is also an emulsion consisting of negatively charged colloidal particles, which are albuminoid substances. Go to: Issues of Concern Emulsions are a sub-class of colloids, which are two-phase systems of matter. Although the terms colloid and emulsion are sometimes used indistinctly, emulsion applies only when both dispersed, and continuous phases are liquids. A colloid is a mixture of a compound that is in a solid, liquid, or gas state and a liquid. The critical difference between a colloid and an emulsion is that colloid can form when any state of matter (solid, gas, or liquid) combine with a liquid. In contrast, the emulsion has two liquid components that are initially immiscible with each other. Emulsions, as liquids, do not demonstrate a static internal structure. Emulsions are thermodynamically unstable as both the dispersed and continuous phases can revert as separate phases, oil, and water, by fusion or the coalescing of droplets. Industries use emulsifying agents, eg, surfactants, to maintain a static structure.[1] Usually, the phase in which the surfactant exhibits the greatest solubility is the continuous phase. Thus, hydrophilic surfactants foster O/W emulsions, whereas lipophilic surfactants promote W/O emulsions. Go to: Clinical Significance Emulsions are frequently used in pharmaceuticals, personal hygiene products, and cosmetics. These are usually oil and water emulsions, albeit dispersed. These emulsions are called creams, ointments, balms, pastes, films, or liquids, depending on their oil-to-water ratios, the addition of other additives, and their intended administration route. Emulsions allow the encapsulation of an active ingredient in the dispersed phase to protect it from degradation and preserve its activity in a sustained manner. They are used to make medications more palatable, to improve their effectiveness via dosage control of active ingredients, and to provide better aesthetics for topical drugs such as ointments. Intravenous and parenteral emulsions may be used for nutritive therapy applications when a patient is unable to consume food or receive nutrition. Fat emulsions serve as dietary complements for patients who cannot get the required fat solely from their diet. The compound may be given as

1. Emulsions

2. INTRODUCTION:
It is thermodynamically unstable system consisting of at least two immiscible
liquid phases, one of which is dispersed as globules (dispersed phase) in the
other liquid phase (continuous phase) stabilized by presence of emulsifying
agents.
• Particles diameter of dispersed phase ranges from 0.25 to 10um.

3. Emulsifying agents
also called emulsifiers are substances
comprising both oil-soluble
hydrophobic (nonpolar) and water-
soluble hydrophilic (polar) portions
that act as a stabilizer of the droplets
(globules) of the internal phase of an
emulsion.

4. PHARMACEUTICALAPPLICATIONS:
• Mask the bitter taste and odor of drugs
• To prolong the release of the drug thereby providing sustained release action.
• Essential nutrients like carbohydrates, fats and vitamins can all be emulsified and
can be Administered to bed ridden patients as sterile intravenous emulsions (TPN).
• Emulsions provide protection to drugs which are susceptible to oxidation or
hydrolysis.
• To formulate externally used products like lotions, creams, liniments etc.

5. TYPES OF EMULSIONS:
• Water in oil emulsion (w/o)
• Oil in water emulsion (o/w)
• Multiple emulsion (o/w/o) (w/o/w)
• Micro emulsion

6. i. OIL IN WATER (O/W):
 Oil droplets are dispersed in a continuous aqueous phase.
 A hydrophilic emulsifier is used.
 These are preferred for oral/ IV administration and cosmetics.

7. ii. WATER IN OIL (W/O) :
 Aqueous droplets are dispersed
in continuous oily phase.
 Lipophilic emulsifier is used.
 Employed for treatment of dry
skin and emollient applications.

8. iii. MULTIPLE EMULSION:
• For making w/o/w emulsion, the dispersed phase is mixed in oil
phase containing lipophilic emulsifier, homogenization is done and
w/o emulsion is formed.
• Now this w/o emulsion is mixed in the aqueous phase containing
hydrophilic surfactant, homogenization is done and as a result
w/o/w emulsion is formed and vice versa for an o/w/o emulsion.

10. iv. MICROEMULSION
o Clear, stable, liquid mixtures of oil, water and emulsifier, frequently in combination with
a coemulsifier.
o In contrast to ordinary emulsion, micro emulsions form upon simple mixing of the
components and do not require the high shear conditions generally used in the formation of
ordinary emulsions.
o The two basic types of micro emulsions are (o/w) and (w/o).
Unlike the common macro emulsion in that:
• Appear as clear transparent solution.
• Diameter of internal phase droplets ranged between 10-200nm.
• Thermodynamically stable.

11. Co-emulsifiers
• auxiliary emulsifiers
• work synergistically
• used in conjunction with primary emulsifiers to enhance the stability, texture, and
performance of an emulsion.
Examples of co-emulsifiers include:
1.Cetyl Alcohol:Lipophilic
2.Glyceryl Stearate: Lipophilic
3.Sodium Stearoyl Lactylate:Hydrophilic

13. Classification Of Emulsion:
1. On The Basis of Mode of Dispersion:
Name Detail Example
O/W (Oil in Water) - Oil is an internal phase
- Water is an external phase
milk
W/O (Water in oil) -Water is an internal phase
- Oil is an external phase
Cold cream
Multiple phases emulsion - W/O/W
- O/W/O
Microspheres for controlled
release

14. 2. On The Basis of Consistency:

15. 3. On The Basis of Particle Size:

16. 4. On The Basis of Route of Administration:

17. 5. On The Basis of HLB Value:

18. Hydrophilic-Lipophilic Balance
• HLB stands for Hydrophilic-Lipophilic Balance, to determine the
optimum balance between hydrophilic (water-attracting) and
lipophilic (oil-attracting) components of an emulsifying agent or
surfactant.
• The HLB value is a numerical scale ranging from 0 to 20, where
lower values represent more lipophilic characteristics and
higher values represent more hydrophilic characteristics.

19. • Low HLB (0-8): Suitable for water-in-oil (W/O) emulsions.
Examples: sorbitan monostearate.
• Intermediate HLB (7-11): Suitable for both water-in-oil (W/O)
and oil-in-water (O/W) emulsions. Examples :polysorbate 60.
• High HLB (12-20): Suitable for oil-in-water (O/W) emulsions.
Examples : polyethylene glycol derivatives.

20. • The nature of the oil and water phases in the emulsion system
influences the required HLB. For instance:
• Oils with higher lipophilicity (e.g., mineral oil) require emulsifiers
with lower HLB values.
• Hydrophilic substances (e.g., proteins) may require emulsifiers with
higher HLB values.
• Balanced HLB values are suitable for forming emulsions with equal
parts of oil and water.

21. Difference between O/W and W/O Emulsion:
•
O/W W/O
Water is as a dispersion medium
Oil is the dispersed phase
Oil is as a dispersion medium
Water is the dispersed phase
They are non-greasy, removable from the skin
surface.
They are not water removable & greasy in nature.
Used externally e.g. vanishing cream Used externally to stop evaporation of moisture from
the skin surface
e.g. Cold cream
Water soluble drugs are released more quickly from
o/w emulsions
Oil soluble drugs are more quickly released from w/o
emulsions
Bitter taste of oils can be masked. So these kinds of
dosage forms are preferred by consumer &
manufacturer.
They are preferred for formulations meant for external
use like creams.
O/W emulsions give a positive conductivity test. W/O emulsions do not give a positive conductivity

22. TESTS USED TO IDENTIFY EMULSIONS:
1. Dilution test
2. Dye test
3. Cobalt chloride filter paper test
4. Fluorescence test
5. Conductivity test

23. 1. DILUTION TEST:
• It is based on the solubility of external phase of emulsion.
• When O/W emulsion is diluted with water, no phase changes occur but
when it is diluted with oil phase changes occur and emulsion is
detected.

24. For w/o emulsions, it is first diluted with oil, no phase changes
occur but when it is diluted with water phase, changes occur and
emulsion is detected.

25. 2. CONDUCTIVITY TEST:
• This test is based on the basic
principle that water is a good
conductor of electricity.
• In case of o/w emulsion, this test
will be positive as water is the
external phase.
• An assembly consisting of a pair of
electrodes connected to a lamp is
dipped into an emulsion.
• If the emulsion is o/w type, the
lamp glows.

26. 3. DYE SOLUBILITY TEST:
o When an emulsion is mixed with a water soluble dye such as amaranth and
observed under the microscope, continuous phase appears red, then it means that the
emulsion is o/w.
o If an oil soluble dye such as Scarlet red C added to an emulsion and the
continuous phase appears red, then it is w/o emulsion. If the scattered globules
appear red and continuous phase colorless, then it is o/w type.

28. 4. FLORESCENCE TEST:
Oils give fluorescence under UV light, while water doesn’t.
Therefore, O/W emulsion shows spotty pattern while W/O emulsion shows continuous fluorescence.

29. 5. COBALT CHLORIDE FILTER PAPER
TEST:
o Filter paper impregnated with
Cobalt chloride and dried (blue)
changes to pink when O/W
emulsion is added.
Color will be unchanged in case
of w/o emulsion.

30. • The test is based on the reaction of water with a mixture of iodine
and sulfur dioxide in the presence of cobalt chloride. The reaction
produces a color change in cobalt chloride from blue to pink.
• A sample of the emulsion is placed on filter paper impregnated with a
mixture of cobalt chloride, sulfur dioxide, and iodine.
• Water in the sample reacts with the reagents on the filter paper,
resulting in a color change from blue to pink.
• The intensity of the pink color is proportional to the water content in
the sample.

31. APPLICATIONS AND UTILITY:
• Difficult to prepare so require special processing techniques.
• Must possess desirable attributes and minimum associated problems.
• Cosmetic and Pharmaceutical applications (topical, oral and parenteral).
• Patient acceptance most important reason for popularity.
• Agents with objectionable taste/texture can be formulated in more palatable form.
• Mineral oil-based laxatives, oil soluble vitamins, high- fat content nutrients as o/w emulsions.
• Absorption and bioavailability (insulin, heparin).
• Topical emulsions – elegance, easy washing, viscosity, appearance, greasiness.
• o/w as water-washable drug bases.
• w/o for dry skin and emollient applications.
• Penetrating ability – rapid and efficient
• Penetration of drug moiety to the site. (TDD)
• I/V administration of lipid nutrients (o/w).

32. Manufacturing Processes or Methods

33. METHODS OF PREPARATION OF EMULSIONS
A) TITURATION METHODS
• Dry gum
• Wet gum
B) BOTTLE AND FORBES BOTTLE METHOD
C) BEAKER METHOD
D) PHASE INVERSION METHOD
E) MEMBRANE EMULSIFICATION METHOD

34. 1.DRY GUM METHOD:
• It is also called Continental method.
• In this method the oil is first triturated with “gum” type emulsifier (usually
acacia) with a little amount of water to form the primary emulsion.
• The trituration is continued till a characteristic ‘cracking’ sound is heard and a
thick white cream is formed.
• This method consists of the “4:2:1” formula.
• 4 parts (volumes) of oil.
• 2 parts of water.
• 1 part of emulsifying agent.

35. • Additional water or aqueous solutions may be incorporated after the primary emulsion is formed.
• Solid substances (e.g., active ingredients, preservatives, color, flavors) are generally dissolved and
added as a solution to the primary emulsion.
• Oil soluble substance, in small amounts, may be incorporated directly into the primary emulsion.
• Any substance which might reduce the physical stability of the emulsion, such as alcohol (which
may precipitate the emulsifier) should be added as near to the end of the process as possible to
avoid breaking the emulsion.
• When all agents have been incorporated, the emulsion should be transferred to a calibrated vessel,
brought to final volume with water, then homogenized or blended to ensure uniform distribution of
ingredients.

36. 2. WET GUM METHOD:
• In this method, the proportions of oil, water, and emulsifier are the
same (4:2:1), but the order and techniques of mixing are different.
• The 1 part gum is triturated with 2 parts water to form a mucilage then
the 4 parts oil is added slowly, in portions, while triturating.
• After all the oil is added, the mixture is triturated for several minutes
to form the primary emulsion. Then other ingredients may be added as
in the continental method.
• more difficult to perform successfully, especially with more viscous
oils, but may result in a more stable emulsion.

38. B) BOTTLE AND FORBES BOTTLE METHOD:
• This method is employed for preparing emulsions containing volatile and non-viscous oils.
• It is not suitable for very viscous oils since they cannot be sufficiently agitated in a
bottle.
• As volatile oils have a low viscosity as compared to fixed oils, they require comparatively
large quantity of emulsifying agent for emulsification.
• In this method, oil or water is first shaken thoroughly and vigorously with the calculated
amount of emulsifying agent.
• Once this has emulsified completely, the second liquid (either oil or water) is then added all
at once and the bottle is again shaken vigorously to form the primary emulsion.
• method consists of the “4:2:2” formula.
• 4 parts (volumes) of oil.
• 2 parts of water.
• 2 part of emulsifying agent.

40. C) BEAKER METHOD
• When synthetic or non-gum emulsifiers are used, the proportions given in the
previous methods become meaningless.
• All oil soluble components are dissolved in the oily phase in one beaker and all
water soluble components are dissolved in the water in a separate beaker.
• Oleaginous components are melted and both phases are heated to approximately
70°C over a water bath.

41. • The internal phase is then added to the external phase with stirring
until the product reaches room temperature.
• The mixing of such emulsions can be carried out in a beaker, mortar,
or blender; or, in the case of creams and ointments, in the jar in which
they will be dispensed.

42. D) PHASE INVERSION METHOD:
• It is also called one step emulsification technique.
• First of all, make a primary emulsion, e.g. o/w emulsion.
• Now add dispersed/internal phase i.e. oil until phase change occurs and emulsion converts from
o/w to w/o emulsion.
• We can also start by making w/o primary emulsion.
• This method is utilized when emulsifying agent is not compatible with external phase of primary
emulsion.
• During phase inversion, drastic physical changes occur including changes in particle size that can
affect drug release both in vitro and in vivo.

44. E) MEMBRANE EMULSIFICATION METHOD:
• In this method, oil and emulsifying agent are triturated to get a primary emulsion.
• This is then extruded into an external aqueous phase with a constant pressure through a porous glass
membrane.
• We can also start with water and emulsifying agent.
• Emulsion of desired particle size can be formed.
• Micro emulsions and nano emulsions using membrane method.
• Advanced Pharmaceutical Emulsions are formulated using membrane method.

47. IDEAL CHARACTERISTICS/PROPERTIES OF
EMULSIFYING AGENTS:
• They can adsorb at oil – water interface; here only surface phenomenon takes place, and no
chemical reaction occurs.
• They can form protective sheets around droplets. This protective sheet will prevent
coalescence.
• These agents can also reduce interfacial tension between two immiscible phases.
• They also increase the viscosity of medium.
• It should be physically and chemically stable, inert and compatible with other ingredients of
the formulation.
• It should be non toxic and non irritant in the concentration used.
• All these characteristics are impossible to find in a single agent that is why emulsifying agents
are given many different names.

48. CLASSIFICATION OF
EMULSIFYING AGENTS:
CLASSIFICATION OF EMULSIFYING AGENTS:
• Emulsifying agents are classified as follows:
• NATURAL.
• SEMI-SYNTHETIC.
• SYNTHETIC.
• FINALLY DIVIDED SOLIDS.
• AUXILLARY EMULSIFYING AGENTS.

49. A. NATURAL EMULSIFYING AGENTS:
• As their name indicates, they are obtained from natural sources.
• These sources include plant and animal sources.
• They are non toxic and relatively stable.

50. EMULSIFYING AGENTS OBTAINED
FROM PLANT SOURCES:
• These are extracted from plant parts.
• Mostly, they are carbohydrates in nature.
• They are less expensive because their source is not costly.
• They may be gums Gum is a polysaccharide which produces a gel of a viscous
solution when it is dispersed in water at low concentrations or mucilages
Mucilage is a polysaccharide substance extracted as a viscous or gelatinous
solution from plant roots, seeds, etc., and used in medicines and adhesives.

51. DISADVANTAGES
• They are susceptible to microbial contamination because they are
carbohydrate in nature.
• They cannot be used for sterile preparations.
• They cannot be used for products having storage for long period of time.

52. • These plant originated emulsifying agents Include:
1. Acacia
2. Tragacanth
3. Agar
4. Pectin

53. 1. ACACIA:
• It is the best-known emulsifying agent for extemporaneous preparations.
• It is mostly used in oral preparations.
• We can make oil in water emulsions using acacia as an emulsifying agent.
• Although it is amphiphilic, its hydrophilic character is more than the
hydrophobic character.
• It is stable in acidic and basic medium as it covers a wide range of pH from 2-
10.

54. RATIO OF ACACIA TO OIL:
• If fixed oil is used, ratio of acacia to fixed oil is 1:4.
• If volatile oil is used, ratio of acacia to volatile oil is 1:2.
• The reason for using more acacia in volatile oil is that volatile oils
are less viscous and thin, therefore, they require more emulsifying
agent.

55. DISADVANTAGES:
• It is susceptible to microbial contamination.
• We cannot make preparations requiring long term storage with acacia.
• We cannot make parenteral preparations using acacia as emulsifying agent.
• They do not play any role to increase viscosity of preparation, so we need to
add thickening agent or viscosity enhancer.

56. 2. TRAGACANTH:
• It is rarely used alone in any formulation.
• It is mostly used in combination with acacia.
• It is used as a thickening agent or viscosity enhancer that is why it is used with acacia which
lacks this property.
• It is also added in gels and suspensions.
• It is also used to make ice creams, jams, jellies, marmalade, mayonnaise etc.

57. RATIO OF ACACIA TO TRAGACANTH:
• For every 10 grams of acacia, 1 gram of tragacanth is added in
emulsions.

58. DISADVANTGES:
• It has no role in decreasing interfacial tension.
• It is susceptible to microbial contamination.
• We cannot prepare sterile preparations and preparations
requiring long term storage.
• We cannot make parenteral preparations.

59. 3. AGAR
• It is a very good thickening agent and is used to make extemporaneous
preparations.
• We use it when we need very thick emulsions.
• We cannot use it directly; therefore, we have to make its 2% mucilage before
using it.
• 2 % AGAR MUCILAGE:
• Take 2 grams agar and add 100 ml water in it; boil this mixture and cool to
40ᴼC.
• This mucilage is used as thickening agent.
• It absorbs moisture because it is hygroscopic in nature.
• When using agar to make oral preparations, a preservative must be added.

60. DISADVANTAGES:
• It is not a very good emulsifying agent.
• We cannot make thin emulsions using agar.
• We cannot make sterile preparations using agar because it acts as
a growth medium for many microorganisms

61. 4. PECTIN:
• It is a natural emulsifying agent obtained mainly from fruits.
• It is generally obtained from the inner rind (white part) of oranges, bananas,
lemons and guavas.
• They are also used in combination with acacia.
• For every 1 gram of acacia, 0.1 gram pectin can be added.
• Pectin is used to make oil in water emulsions.
• It is also added in chocolates and juices because it is inexpensive.

62. EMULSIFYING AGENTS OBTAINED
FROM ANIMAL SOURCES:
• These are obtained from animal parts like bones, eggs, skin etc.
• These animal originated emulsifying agents include:
1. GELATIN
2. EGG YOLK
3. WOOL FAT

63. 1.Gelatin
• It is similar to agar; the only difference is that it is obtained from animal source.
• Vegetarians do not use gelatin; they use agar.
• It is carbohydrate in nature.
• We cannot use it directly; first its mucilage is prepared by boiling 1 gram gelatin
in 100 ml of water because it will not dissolve in water at room temperature.
• It is used as a thickening agent in jams, jellies, cheesecake etc.
• It is tasteless, so can be added in oral preparations.
• It is used in preparations which are stored for less storage time.
• Preservative must be added in preparations in which gelatin is added.

64. 2.EGG YOLK:
• Egg yolk contains lecithin and cholesterol which acts as emulsifying agent.
• Lecithin is a mixture of phospholipids such as phosphatidylcholine.
• It is extracted from egg yolk and soya beans as well.
• Its two famous varieties are soya lecithin and egg yolk lecithin.
• In emulsion, ratio of lecithin is 15 grams for every 120 ml of fixed oil.
• It is also used in liposome formulation (liposome is a minute spherical sac of
phospholipid molecules enclosing a water droplet, especially as formed
artificially to carry drugs or other substances into the tissues).
• When a preparation is made containing lecithin, it is stored in refrigerator to
stop spoilage.

65. 3. WOOL FAT:
• It is also called anhydrous lanolin.
• We can make oil in water emulsions with wool fat.
• It is used to make external/ topical preparations.
• Wool fat can absorb 50% water of its weight, so require large quantity of
water.

66. B. SEMI-SYNTHETIC EMULSIFYING AGENTS:
• Semi-synthetic emulsifying agents are made through modification in the structure
of natural emulsifying agents to overcome drawbacks in natural emulsifying agent.
• They are mainly derived from cellulose derivatives.
• They include: Methylcellulose, Carboxymethylcellulose,
Hydroxypropoxymethylcellulose.

67. C. SYNTHETIC EMULSIFYING AGENTS:
These emulsifying agents are totally
formulated in laboratory.
1.Anionic emulsifying agents:
2.Cationic emulsifying agents:
3.Non-ionic emulsifying agents:
4. Amphoteric emulsifying agents:

68. 1. ANIONIC EMULSIFYING AGENTS:
a) ALKALI SOAPS:
• They are negatively charged.
• We can make oil in water emulsions with them.
• They precipitate in acidic conditions.
• Examples include: sodium, potassium and ammonium salts of fatty
acids.
b) SOAP OF DI/TRIVALENT METALS:
• They promote w/o emulsions. E.g. Calcium oleate.

69. c) AMINE SOAPS:
• They have neutral pH.
• They are incompatible with acids and high concentration of electrolytes.
• They produce o/w emulsion.
d) SULPHATED AND SULPHONATED COMPOUNDS:
• They are stable over high pH range.
• They make o/w emulsions.
• E.g. Sodium lauryl sulphate.

70. 2. CATIONIC EMULSIFYING AGENTS:
• These are quaternary ammonium compounds.
• They have positive charge.
• E.g. Cetyl trimethylammonium bromide (Cetrimide) and benzalkonium chloride.
Disadvantages:
• They are toxic and irritants.
• They are incompatible with anionic surfactants and polyvalent anions.
• They are unstable at high pH.

71. 3.NON-IONIC EMULSIFYING AGENTS:
• They have low toxicity and irritancy so suitable for oral and
parenteral administration.
• They are less sensitive to pH change or to addition of electrolytes
• E.g. Tweens (polyethylene fatty acid ester), Spans (sorbitan fatty
acid ester).

72. 4. AMPHOTERIC EMULSIFYING AGENTS:
• They have both positive and negative charge which depends on pH
of the system.
• At low pH, they are cationic.
• At high pH, they are anionic.
• E.g. lecithin: used to stabilize I.V, fat emulsion.

73. D. FINELY DIVIDED SOLIDS:
• They form a coherent film which prevents coalescence of the dispersed
globules.
• They are used to make both o/w and w/o emulsions.
• If the particles are preferentially wetted by the aqueous phase, o/w emulsion
forms.
• It the particles are preferentially wetted by the oil phase, w/o emulsion
forms.
• E.g. bentonite, aluminium magnesium stearate, attapulgite, colloidal
anhydrous silica, kaolin, chalk, talc.

74. E. AUXILLARY EMULSIFYING AGENTS:
• They are miscellaneous emulsifying agents having properties
similar to all other emulsifying agents.
• They have weak emulsifying properties and are used in
conjunction with other emulsifying agents.
• They stabilize emulsion by thickening the formulation.
• Examples: fatty acids (stearic acid), fatty alcohols (stearyl or cetyl
alcohol), fatty esters (glycerin monostearate).

76. ANTIMICROBIAL PRESERVATIVES
✓ Less toxic
✓ Stable to heat and storage
✓ Chemically compatible
✓ Reasonable cost
✓ Acceptable taste, odor and color.
✓ Effective against fungus, yeast, bacteria.
✓ Available in oil and aqueous phase at effective level concentration.
✓ Preservative should be in unionized state to penetrate the bacteria.
✓ Preservative must no bind to other components of the emulsion.