This document provides information about emulsions, including their definition, advantages, types, tests for identification, classification, formulation, preparation, stability, and differences from suspensions. Key points include: - An emulsion is a biphasic liquid dosage form with one liquid dispersed as fine globules in another immiscible liquid, stabilized by an emulsifying agent. - Emulsions can improve palatability, protect unstable drugs, and aid in drug absorption. - The main types are oil-in-water and water-in-oil emulsions, classified based on the dispersed and continuous phases. - Emulsion stability depends on factors like emulsifying agent, preservation, antioxidants, and

1. BLDF-
EMULSION
Prepared By:
Lecturer: Mr. S. S. Mistree
M-pharm (P’ceutics)
Sub: Pharmaceutics-II
Ishwar Deshmukh Institute of Pharmacy,
Digras
Yavatmal-445302
2020-21

2. CONTENTS
Introduction
Advantages
Types of emulsion
Test for identification of types of emulsion
Classification of emulsion
Formulation of emulsion
Preparation of emulsion
Stability of emulsion
Storage of emulsion
Difference between emulsion and suspension
Reference

3. INTRODUCTION
Define: It is a Biphasic liquid dosage form having two immiscible
liquid, in which one liquid is distributed as fine globules into the
other.
 As like suspension, Also it is made up of with two phase i.e.
Dispersed phase and Continuous phase.
 Dispersed phase- fine globules of liquid
 Continuous phase- the liquid in which globules are distributed
 In general, it is difficult to mix immiscible liquid with each other.
 i.e. we can not mix oil with water
 But it become possible if we add emulsifying agent.
Emulsifying agent: The agent which reduce the interfacial tension
between two phase i.e. oily phase and aqueous phase. And make them
miscible with each other.

4.  Actually, it form a thin film over the globule in order to scatter them
totally in continuous phase thus we get stable emulsion.
 The globule size in emulsion different between 0.25 to 25 micron
diameter.
 Emulsion categories into different form according to their globule
size:
 Coarse emulsion- having large globules
 Fine emulsion- having globule size 5 micron
 Micro-emulsion- having globule size less than 10 nm (milky and
transparent )
 If the two phase have same refractive index, a transparent emulsion is
produced.

5. ADVANTAGES
 Drugs having unpleasant taste and odor, can made more palatable for
oral administration in the form of emulsion.
Eg: castor oil, cod-liver oil
 Drug have sensitive to oxidation or hydrolysis can dispense in
emulsion form.
 Most of external preparation are formulated in emulsion form.
Eg: lotion, cream, foam aerosols
 Who are not able to take medicine containing fat, carbohydrate and
vitamins by orally. Can dispense it in the form of sterile stable
intravenous emulsion.
 Emulsion increase the absorption of oil when taken internally.
 Recently, radio opaque emulsion are used as diagnostic agent in X-
ray examination.

6. TYPES OF EMULSION
Emulsion divided into following types on the basis of their phase:
Oil in Water type-(O/W)
Water in Oil type -(W/O)
Oil- Water-Oil -(O/W/O)
Water-Oil-Water -(W/O/W)
1. Oil in Water- (O/W):
 In this of emulsion, oil is act as dispersed phase whereas water as
continuous phase/ dispersion media
 This type are generally prepared for internal use only.
 For this emulsion only some selected kind of emulsifying agents are
used, such as- gum acacia, tragacanth, methyl cellulose, saponin,
synthetic substance and Monovalent soaps- Na+, K+, NH4

7. 2. Water in oil (W/O):
 In which water is act as dispersed phase and oil is in continuous phase.
 This W/O type prepared for external use such as- lotions, creams
 In which some emulsifying agents used like- wool fat, resin, beeswax
and divalent soaps- Ca++, Mg++ and Zn++

8. IDENTIFICATION TEST FOR EMULSION

9. CLASSIFICATION OF EMULSION
 There is various way to classify the emulsion, however from the
dispensing point of view and mode of administration emulsion can be
classified as follow-
A- On the basis of type of emulsifying agent used in the preparation
of emulsion:
B-On the basis of their mode of administration:
A-
1-Emulsion containing natural gum- Eg- gum acacia, tragacanth and
mucilage of Irish moss
2-Emulsion containing gum substance-Eg- Cellulose and its derivatives
and salt of alginic acid
3- Emulsion containing various soaps- Eg- Sopanin , sodium acetate

10. 4- Emulsion containing saponin, bees wax
5- Emulsion containing starch
6- Emulsion containing natural waxes- Eg- wool fat and bees wax
7-Emulsion containing synthetic waxes- Eg- emulsifying wax and
cetomacrogol emulsifying agent
8-Emulsion containing other emulsifying agent- Eg- pectin, egg yolk,
gelatin and lecithin's.
B-
1-Emulsion for oral administration-
 Usually O/W type of emulsion
 Used to administration oils having medicinal value- Eg- castor oil,
olive oil, almond oil, cod-liver oil and liquid paraffin
2-Emulsion for external use-
 It may either O/W or W/O type.
 But external emulsion is a W/O type and commonly O/W type
preferred over the W/O .

11. 3- Emulsion for parenteral use-
 Used to administer of soluble vitamins.
 A, D, E and oil soluble sex hormones.
 Bcz their absorption in this form is vary rapid.
4- Emulsion for rectal use-
 This kind of emulsion used in the form of enema for evacuation of
bowl
 Starch mucilage is used in the preparation of enema.

12. FORMULATION OF EMULSION
A-Emulsifying agent
B-Preservation of emulsion
C-Antioxidants
D-Flavors
A- Emulsifying agent:
 The emulsifying agent reduce the interfacial tension between two
phase. i.e. oily phase and aqueous phase thus make them miscible with
each other and form a stable emulsion.
 Emulsifying agent also known as emulgents or emulsifier.
 There are various types of emulsifying agents available to produce
stable emulsion.
 Hence it is very difficult to select proper kind of E-agent

13.  One single emulsifying agent has not posses all required properties to
formulate stable emulsion.
 Hence it become necessary to used two or more than two emulsifying
agents instead of one to prepare stable emulsion.
 Griffin was a scientist who discovered one method for calculating
balanced mixture of emulsifying agent to produce particular type of
emulsion.
 It is called the Hydrophile Lipophile Balance or HLB method
 In which every emulsifying agent arrange with a number on HLB
Scale. ( divided into 18 unit )
 Emulsifying agent with higher number ( 8-18 ) possess hydrophilic
properties and produce O/W type of emulsion.
 E-agent with lower number ( 3-6 ) possess lipophilic properties and
produce W/O type of emulsion.

16. IDEAL PROPERTIES OF EMULSIFYING AGENT
 It should capable to reduce interfacial tension between two immiscible
liquid.
 It should compatible with other ingredients of preparations.
 It should be non-toxic
 It should able to produce and maintain the required consistency of
emulsion.
 It should be chemically stable
 It should able to keep globules distributed into continuous phase.

17. CLASSIFICATION OF EMULSIFYING AGENT

18. 1. Natural emulsifying agent from vegetable sources:
 These are the carbohydrate kind of emulsifying agent such as gum
and mucilaginous substance.
 Are the anionic in nature and produce O/W type of emulsion.
 Those emulsion formulated by using these kind of agent are need to
add suitable kind of preservative to preserve it from attack of
bacteria's.
 Because, carbohydrate is a suitable for bacterial growth.
Eg- Acacia, tragacanth, Agar, Pectin, Starch and Irish Moss, etc.
a) Acacia-
 It is a one of the best emulsifying agent used to prepare internally
used preparation.
 Emulsion containing gum acacia are very attractive in appearance ,
quite palatable and stable at pH ( 2 to 10 )
 Acacia containing emulsion has low viscosity therefore to form
creaming occurred quite rapidly.

19.  We can overcome this problem by adding other emulsifying agent
with gum acacia such as- tragacanth, agar, pectin.
 These combination increase viscosity and make it stable.
b) Tragacanth-
 Tragacanth are very rarely used as emulsifying agent.
 It is never used alone, because it form very coarse and thick
emulsion.
 This problem overcome by passing it through a homogenizer or if
tragacanth is used along with gum acacia.
c) Pectin-
 Its 1% mucilage in water used as emulsifying agent.
 Pectin is incompatible with alkalies, strong alcohol, tannic acid and
salicylic acid.
d) Agar-
 It is not a good kind of E-agent as itself, because it form very coarse
and viscous emulsion.

20.  But its 2% mucilage by dissolving in boiling water and cooled at
45oC as E-agent.
e) Starch-
 It is rarely used because it form very coarse emulsion.
 Generally, used to prepare enema kind of emulsion.
f) Irish Moss-
 It is also popular with its chondrus name.
 Actually, it is used as thickening agent.
 It is used along with gum acacia for the emulsion containing cod-
liver oil, Its help to mask the unpleasant odor and taste of the oil.
 Generally its3% solution used as emulsifying agent
2. Natural emulsifying agent from animal sources:
Eg- Wool Fat, Egg Yolk, Gelatin
a)Wool fat-
 Added to emulsion for external use.

21.  It produce O/W type of emulsion.
 It can absorb about 50% of water.
b) Egg yolk-
 It is mainly used in specific kind of preparation for internal use , bcz it
get spoiled during transportation.
 Egg yolk containing emulsion need to add preservative in it and may
store in refrigerator.
 In concentration between 12-15% act as emulsifying agent.
c) Gelatin-
 1% gelatin used as emulsifying agent.
 Emulsion containing liquid paraffin made with gelatin, prepared
emulsion is quite white and have agreeable taste.
 Gelatin containing emulsion need to preserve with suitable
preservative, bcz its prone to bacterial growth.

22. 3. Semi-synthetic polysaccharides:
Eg- methyl cellulose, sodium carboxy methyl cellulose
a) Methyl cellulose-
 It is actually, synthetic derivatives of cellulose.
 Widely used as suspending, thickening, emulsifying agent with 2%
concentration.
 It is added to emulsion containing vegetable or mineral oil but get ppt
out in presence of electrolytes.
b) Sodium carboxy methyl cellulose-
 It is generally used as emulsion stabilizer with concentration of 0.5-
1%.
 It is soluble in both cold and hot water.
4. Synthetic emulsifying agents:
Eg- anionic, cationic, non- ionic
a) Anionic-
Eg- alkali soaps, metallic soaps, sulphated alcohol and sulphonates are
used as anionic emulsifying agent.

23.  Soap emulsions are used for external application.
 From the sulphated alcohol, sodium lauryl sulphate is commonly used
as emulsifying agent.
 It produce a O/W type of emulsion.
b) Cationic-
 Actually quaternary ammonium compound are used as a cationic
emulsifying agent.
Eg- benzalkonium chloride, benzethonium chloride, cetrimide, etc.
 These cationic kind of emulsifying agent bear a positive charge (+) and
mainly used in external preparation.
Eg- skin lotion and creams
c) Non-ionic-
 The glyceryl esters and sorbitan fatty acid esters are commonly used as
non-ionic emulsifying agent.
Eg- glyceryl monostearate, sorbitan fatty acid esters

24.  These are widely used bcz it keeps stable the emulsion on wide range
of pH changes.
5. Inorganic emulsifying agents:
-Milk of magnesium (10-20%)
-Magnesium oxide ( 5-10%)
-Magnesium aluminium silicate (1%)
 These are used to prepare coarse O/W type of emulsion
 Bentonite (5%) is used to prepare O/W or W/O type of emulsion.
 When Bentonite used to prepare O/W emulsion, then oil added to
suspension of bentonite.
 Whereas it is used to prepare W/O emulsion, oil place to container and
then bentonite suspension added to it with continuous stirring.

25. 6. Alcohols:
Eg- carbowaxes, cholesterol, lecithin
a) Carbowaxes-
 Mainly used to prepare ointment or cream.
 Carbowaxes (mol.wt-200-700) are viscous, light colored, hygroscopic
liquid.
 Carbowaxes (mol.wt-1000 and above) are waxes like a solid
 By using right type of carbowaxes or mixture of carbowaxes we can
prepare desire emulsion.
b) Cholesterol-
Eg- cetyl alcohol, stearyl alcohol, cholesterol and glyceryl monostearate
 Are used as a stabilizer.
 Are not used alone, used with some other e-agent.

26. c) Lecithin-
 It is rarely used because it darken the color when expose to light and
easily oxidized.
 Some time used to prepare W/O emulsion.
B. Preservation of emulsion
 Emulsion prepared by using various kind of emulsifying agent like-
carbohydrate, protein, sterol and some surfactant.
 Due to these agent chances of bacterial, fungal or mould growth in
emulsion in presence of water.
 Due to contamination may cause unpleasant odor, taste, and
discoloration.
 Due to breakdown of E-agent changes occur in consistency of
emulsion ,lead to cracking of emulsion.

27. Other reason of contamination of emulsion:
-Use of unclean equipment in emulsion preparation.
-Use of contaminated natural E-agents. Eg- gums, starch and clay
-Taken wrong ratio of water and oil
-Not use of de-ionized or purified water
-Not maintain suitable pH of the preparation
Steps to overcome contamination and helps to maintain a stable
emulsion:
-Use cleaned equipments
-Use standard quality materials
-Maintain required ratio of water, oil and gum
-Use purified or fresh boil water
-Use good quality of container and closures
-Maintain required pH of preparation.

28.  To preserve emulsion properly from contamination, necessary to
maintain above precaution.
 Along with precaution add suitable kind of preservatives in
formulation of emulsion.
Eg-
-Benzoic acid (0.1-0.2%)
-Methyl paraben and propyl paraben (0.1-0.2%)
-Chloroform (0.25%)
-Chlorocresol (0.1%)
-Cetrimide (0.002-0.01%)
-Phenylmercuric nitrate (0.004-0.01%)
C. Antioxidants:
 During storage of emulsion, fats or emulsifying agents undergo
oxidation by atmospheric oxygen.
 This can be prevented by adding suitable anti-oxidant, eg- tocopherol,
gallic acid, ascorbic acid.

29.  Also sometime oxidation occurred due to enzyme produced by micro-
organism.
 This problem can be prevented by adding anti-microbial agent.
Ideal qualities of anti-oxidant:
-Should be readily soluble in medium
-Should be effective in low concentration
-Should be non-toxic and non-irritant
-Should be compatible with other ingredients
-Should be colorless, odorless, tasteless
D. Flavors:
 Vanillin for liquid paraffin
 Benzaldehyde for emulsion containing cod-liver oil
 Combination of sweetening and flavor also preferred for increasing
palatability of emulsion.

30. PREPARATION OF EMULSION

31. For the preparation of emulsion, various methods are used, following are
the some methods by which we can prepare emulsion on a small scale-
Dry gum method, Wet gum method, Bottle method, Other methods
Dry gum method-
1.Calculate required quantity of oil:water:gum for preparation of
primary emulsion.
2. Take dry M-cylinder and measure required amount of oil and transfer
into dry mortar
3. Add required amount of gum acacia into it and triturate rapidly until
uniform mixture.
4. Add required amount of water and triturate continuously till clicking
sound is produced and product become white or nearly white
5. In this stage those emulsion produced are called primary emulsion.
6. Add more water to produced required volume.
7. Transfer the emulsion to a bottle, cork, label and dispense.

32. Wet gum method-
1. Same as dry gum method (step-1)
2. Take a required quantity of fine powder of gum acacia in dry mortar
and add water and triturate it so as to form mucilage.
3. Add required quantity of oil in small portion with rapid trituration till
clicking sound produce and product become white.(k/as primary
emulsion)
4. Add more water into primary emulsion to produce required volume.
stir thoroughly so to form uniform emulsion.
5. Transfer the emulsion to a bottle, cork, label and dispense.
Bottle method-
1. This method used for the preparation of emulsion of volatile oil or
other non-viscous oil.
2. Take a large bottle, transfer required amount of oil into it and add fine
powder of gum acacia.
3. Shake the bottle continuously till oil and gum are mixed.

33. 4. Into above add calculated amount of water at once.
5. Shake the mixture continuously to form primary emulsion.
6. Add more water by small-small portion with constant stirring to
produce final volume.
7. Transfer to suitable container, cork, label and dispensed.
Other method-
 Various homogenizer and blenders are used for preparation of
emulsion.
 Homogenizers- hand homogenizer and silver-son mixer homogenizer,
colloidal mill
Principle- the large globules in coarse emulsion are broken into smaller
globules by passing them under pressure through a narrow orifice.
 A coarse emulsion is produced by mortar, transfer to hand
homogenizer and pass many time till desired satisfaction emulsion
produced.
 By using colloidal mill can be produced fine emulsion having globule
size less than 1 micron on large scale manufacturing.

35. Hand homogenizer-
 It’s a hand operating machine and by this coarse emulsion make fine.
 The emulsion placed in hopper and do up and down movement of the
handle.
 It draw the emulsion into inlet value and forcefully pass through the
fine orifice.
 The fine globules are broken into fine globules of uniform size.
Silver-son mixer homogenizer-
Construction-
 It consist of electric motor, shift, stand and emulsifier head is covered
with fine meshed stainless steel sieve.
 The emulsifier head consist of number of blades, blades are rotated by
electric motor, hence produce very high speed and powerful shearing
action.
Working-
 Emulsifier dipped in a vessel containing immiscible liquid.

36.  When the motor is started, liquids sucked through the fine holes and
the oil is reduced into fine globules due to rotation of blades.
 So a fine emulsion is produced, which is then expelled out.

37. STABILITY OF EMULSION
 If emulsion remain as such after its preparation i.e. dispersed globules
are uniformly distributed into dispersion medium during it storage,
then we shall call it stable.
 As well as should be chemically stable and there should not any
bacterial growth during its shelf life.
Following are the three changes occurs during the storage of emulsion-
A. Cracking
B. Creaming
C. Phase inversion
A. Cracking-
 It’s a separation of disperse and continuous phase from each other.
 Its occur due to coalescence of disperse phase globule, and difficult to

38. re-disperse by shaking.
Reason of cracking-
1. By addition of opposite type of emulsifying agent
2. By decomposition or precipitation of E-agent
3. By addition of common solvent
4. By micro-organisms
5. Change in temperature
6. By creaming
1. By addition of opposite type of E-agent-
 Soap of monovalent metals produce O/W emulsion
 Soap of divalent metals produce W/O emulsion
 But addition of M-metal soaps to D-metal soap emulsion or vice-versa
may lead to cracking of emulsion.

39. 2. By decomposition or precipitation of E-agent-
 If acid added to alkali soap emulsion (turpentine liniment), decompose
to E-agent may lead to emulsion cracking.
 If NaCl added to sodium or potassium soap emulsion, E-agent
precipitate out may lead to emulsion cracking.
3. By addition of common solvents-
 If common solvent added to emulsion which either miscible with
disperse phase, E-agent and continuous phase.
 Due to this, formation of one phase or clear solution, may lead to
emulsion cracking.
Eg- Addition of alcohol to turpentine liniment, lead to formation of clear
solution.
Bcz- turpentine oil, soft soap and water are soluble in alcohol.
4. By micro-organisms-
 If emulsion is not carefully store, may chances of bacteria or mould
growth, lead to destruction of E-agents, hence emulsion become crack.

40.  Hence, it is desirable that all emulsion should store for long period
with careful preservation.
5. Change in temperature-
 When emulsion are store for long time , an increases temperature,
may reduce viscosity and encourage creaming and lead to cracking.
 Whereas store in low or freezing temperature, the water content
become ice and shaking may reform the emulsion.
6. By creaming-
 Creamy emulsion are very suitable to crack than homogenous
emulsion.
 Hence, care should taken to prevent creaming as far as possible.

41. B. Creaming-
 It is a upward movement of disperse globules to form a thick layer at
surface of emulsion.
 It is a temporary condition, it is to be re-dispersed by mild shaking.
 As far as possible creaming should avoid bcz it may lead to cracking
with complete separation of two phase.
 According to Stoke’s law, the rate of creaming depend on various
factors, this can be explained by below equation-
2r*r (d1-d2)g
V= ------------------------
9n
Where-
V- rate of creaming
r- radius of globules

42. d1- density of dispersed phase
d2- density of continuous phase
g- gravitational constant
n- viscosity of dispersion medium
1. Radius of globules-
 Rate of creaming= the radius of globules
 Large globule size=more will creaming
 Smaller globule size= less will creaming
 Smaller globules size form slow creaming than large globules.
 Solution- creaming can reduced by reducing the globule size by
passing through homogenizer.
2. Difference in density of dispersed and continuous phase-
 Rate of creaming depend on difference between density of dispersed
and continuous phase.
 Greater difference= more creaming

43.  Difference can be reduced but its not required therapeutically.
3. Viscosity of dispersion medium-
 Rate of creaming=1/viscosity of dispersion medium
 Viscosity can be increased by adding tragacanth or methyl cellulose
 High viscosity is not desirable bcz difficult to re-dispersed and to pure
from container.
4. Storage condition-
 Emulsion should store in cool place, bcz increasing temp reduce the
viscosity may lead to creaming.
 Also freezing should avoided bcz may lead to cracking.
C. Phase inversion-
 Its means conversion of emulsion from one type to another type.
i.e. O/W changes to W/O or vice versa
Reason of phase inversion
1. Addition of an electrolyte

44. 2. Change in phase volume ratio
3. Temperature change
4. Changing the emulsifying agent
Solution to treat this condition
1. It is minimize by keeping concentration of dispersed phase between
30-60%
2. Storing emulsion in cool place
3. Using suitable kind of E-agent in adequate concentration.

45. STORAGE OF EMULSION
Containers-
 Packed in container having a adequate air space above emulsion for
adequate shaking before its use.
 Emulsion meant for internal use, should packed in wide mouth bottle
for easy withdrawal of emulsion.
 Don’t use metallic closers
 Wide mouth amber glass bottle very suitable for storage of emulsion.
Labeling-
 Secondary label- ‘’shake well before use’’ is need to mention
Storage-
 Should be store in air tight container
 protected from light
 protect from high temperature or freeze but should store in cool place.

46. DIFFERENCE BETWEEN
1. It is a BLDF containing two
immiscible liquid, one of
which dispersed as minute
globules into other.
2. Dispersed globule size 0.25-
25 micron
3. Need E-agent to make stable
emulsion
4. Its type-O/W and W/O
5. Several test are here to
identify its type.
6. Freezing should avoided, may
cause cracking of emulsion
1. It is BLDF of medicament in
which fine solid particles are
dispersed in liquid or semi-
solid vehicle.
2. Particle size of dispersed solid
of 0.5-5.0 micron.
3. Need suspending agent to form
stable suspension.
4. Its type- flocculated and non-
flocculated of suspension
5. There is no any test to identify
its type.
6. Freezing avoided, may lead to
cake formation.
EMULSION SUSPENSION

47. REFERENCE
R. M. Mehta, pharmaceutics-II, second adition-2003,reprint
2010,vallabh Prakashan. Pg. No. 138 to 155.