This document discusses emulsions. It defines an emulsion as a dispersion of small globules of one liquid distributed throughout another immiscible liquid. Emulsions are classified based on the dispersed phase as oil-in-water or water-in-oil, and based on droplet size as macroemulsions or microemulsions. Emulsifying agents are substances that stabilize emulsions by forming films at the liquid interfaces. Various natural, semi-synthetic, and synthetic agents are described. Methods for preparing emulsions include dry gum, wet gum, and bottle methods. Factors that cause emulsion instability like cracking and creaming are also outlined.

1. EMULSION
Mr.R.R.Patil
Dr.Shivajirao Kadam College of
Pharmacy, Kasbe digraj, Sangli

2. INTRODUCTION
• An emulsion is a dispersion in which the
dispersed phase is composed of small globules
of a liquid distributed throughout a vehicle in
which it is immiscible.
• Vigorous shaking may break one liquid into
globules that become distributed throughout
the other, this condition is only temporary as
separation quickly take place on standing.
• e.g castor oil and water

3. Classification of emulsions
Based on dispersed phase
Oil in Water (O/W): Oil droplets dispersed in water
Water in Oil (W/O): Water droplets dispersed in oil
Based on size of liquid droplets
0.2 –50 mm Macroemulsions (Kinetically Stable)
0.01 –0.2 mm Microemulsions (Thermodynamically
stable)

4. Emulsifying Agent
• Emulsifying agent are the third substance or agent which
produce the film at the interface between two immiscible
liquids and stabilised the system those agent are called
emulsifying agent or emulsifier or emulgent.
• Pharmaceutically acceptable emulsifiers must also
 be stable
 be compatible with other ingredients
 be non –toxic
 possess little odor , taste , or color
 not interfere with the stability of efficacy of the active agent

5. • Emulsion dosage form present in liquid or semi-solid form.
• Liquid emulsions are used internally, externally or parenterally.
 The o/w type of emulsions orally used bec. they disguise the
taste or oiliness of medicinal oils such as paraffin, cod liver oil
& also improve absorption of oils.
 for some patients, o/w type of nutritive oils & fats are
administered intravenously.
 For both liquid & semi-solid external preparations o/w are
superior to w/o emulsions.
 w/o type of emulsion used on non-weeping surface or dry
surface to prevent dehydration (emollient).

6. Theory of Emulsification
• INTERFACIAL TENSION:
Interfacial or surface tension exists when two phases are
present. These phases can be gas/oil, oil/water, or
gas/water. Interfacial tension is the force that holds the
surface of a particular phase together and is normally
measured in dynes/cm.
• INTERFACIAL FILM:
In interfacial film , an amphiphilic molecules to align it self
at water-oil interface in the favorable position such as,
- Oleophilic portion in oil phase.
&
- Hydrophilich portion in water phase.

7. e.g. O/W
OLEOPHILIC PART
HYDROPHILIC PART

8. • For the amphiphilic to be concentrated at the
interface, it must be balanced with the proper
amount of water- and oil-soluble groups.
• If the concentration of the emulsifier is high
enough, it forms a rigid film between the
immiscible phases, which acts as a mechanical
bar to both adhesion & coalescence of the
emulsion.

9. Determination of Emulsion Type
 Dilution Test:
- o/w emulsion can be diluted with water.
- w/o emulsion can be diluted with oil.
 Conductivity Test:
- Electrodes are used in that test.
- In o/w type emulsion the lamp will light.
- In w/o type emulsion the lamp fails to light.

10.  Dye-Solubility Test:
- water soluble dye will dissolve in the aqueous
phase.
- oil soluble dye will dissolve in the oil phase.
 CoCl2 / Filter paper Test:
Filter paper impregnated with CoCl2 dried
(blue) changes to pink when o/w emulsion is
added. This test may fail if emulsion is unstable or
break in the presence of electrolytes.

11. Classification of Emulsifying Agents
1. Natural emulsifying agents from vegetable
sources
a. Acacia
b. Tragacanth
c. Agar
d. Pectin
e. Starch

12. 2. Natural emulsifying agents from animal sources
a. Gelatin
b. Egg yolk
c. Wool fat
3. Semi-synthetic polysaccharides
a. Methyl cellulose
b. Sodium carboxymethyl cellulose.
4. Synthetic emulsifying agents
a. Anionic
b. Cationic
c. Non-ionic

13. 5. Inorganic emulsifying agents
a. Milk of magnesia
b. Magnesium oxide
c. Magnesium trisilicate
d. Bentonite
6. Saponins
7. Alcohols
a. Cholesterol
b. Carbowaxes
c. Lecithin

14. Natural emulsifying agents from vegetable sources
• Acacia:-
- Acacia 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.

15. • 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 stabiliser,
particularly in acacia emulsions.
- A suitable proportion is 1 part to 10 parts of acacia.

16. • 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.
- If it is used as emulsifying agent a ratio of 0.1 gm
per gram of acacia.
- 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.

17. • AGAR:-
- Agar is a dried extract from certain seaweeds.
- It is not a good emulsifying agent as it forms a
very coarse & viscous emulsion.
- It was formerly used as an emulsion stabiliser in
liquid paraffin emulsions prepared with acacia.
- Generally 2% mucilage of agar is prepared by
dissolving it in boiling water & cooled to 450 C.
below this it forms a gel which is not useful in
emulsion.

18. • Natural emulsifying agents from animal sources
• Gelatin:-
- Gelatin is mainly used for the emulsification of
liquid paraffin.
- 1% concentration forms the emulsion.
- Gelatin emulsions are prone to bacterial growth
therefore suitable preservative must be
incorporated.

19. • Egg yolk:-
- Egg yolk itself is an emulsion bec. It contains
lecithin & cholesterol which acts as emulsifying
agent.
- It is generally used for the emulsification of fish
liver oils.
- 15grms egg yolk obtained from each egg which
can emulsify about 120 ml of fixed oil & 60 ml
volatile oil.
- Preservatives must be used in that type of
emulsion.

20. • Wool Fat:-
• Wool fat also called as anhydrous lanolin
• It is type of wax. It’s M.P is 36 to 400 C.
• It consist of fatty acid esters of cholesterol & fatty alcohols.
• 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.
• It absorbed 50% of water but it mixed with other fatty substances it
can emulsify several times its own weight of water & other
hydroalcholic liquids.

21. • 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 used emulsification of mineral oil & vegetable oil but
less satisfactory for cod liver oil.
• It is soluble in hot water.
• It is stable to pH changes & alcohol but produces ppt in the
presence of large amounts of electrolytes.

22. • 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.

23. • Synthetic Emulsifing Agents or Surfactants :
• Anionic:-
• It is used good emulsifing agents for those emulsions
which are applicable for external purpose.
• various alkali soaps, metallic soaps, sulphated alcohols &
sulphonates are used as emulsifing agents.
• It produce O/W type of emulsion.
• Sulphated salts, sodium lauryl sulphate is commonly used
as emulsifing agent in topical preparation
• Dioctyl sodium sulphsuccinate is e.g. of sulphonates used
internally for soften the stools.

24. • Cationic:-
• They are used emulsifing agent in O/W type of
emulsions.
• Quaternary ammonium compounds are only group
that extensively used emulsifing agent.
• They have show against bacterial properties, so it is
used for disinfectant.
• It is not good emulgent when it 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.

25. • Non-Ionic:-
• Non-ionic surfactant are widely used in the
pharmaceutical emulsion.
• Those 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.

26. Inorganic Emulsifying Agents:-
• Various inorganic emulsifying agents are used such
as milk of magnesia, magnesium oxide, bentonite
etc.
• They produce O/W type of emulsions.
• But bentonite used either O/W or W/O type of
emulsion.
• 5% suspension of bentonite is used as a emulsifying
agent.
• For O/W oil is added to the bentonite suspension.
• For W/O oil is placed in the container & then
bentonite suspension added to the oil & rapid
stirring.

27. SAPONINS
Saponins are rarely used as
emulsifying agents.
Quillaia tincture or panama tincture &
liquid extract may be used.

28. ALCOHOLS
• Cholesterol:-
• A number of high molecular weight alcohols
are used.
• They used as a stabiliser in emulsion
preparation.
• Cetyl alcohol, stearyl alcohol, glyceryl
monostearate included in this group.

29. • Carbowaxes:-
• They act as non-ionic emulsifying agents.
• They are used in the ointments & cream
preparations.
• Their M.W various from 200-1000
• Carbowaxes 200-700 are viscous & light
coloured.
• Carbowaxes M.W 1000 are wax like solid.

30. • Lecithins:-
• Lecithin forms W/O type emulsion.
• It is rarely used as emulsifying agent.
• Because it exposed to light & gets easily
oxidised.

31. Hydrophile-Lipophile Balance (HLB)
• Discovered by griffin scientist in 1954.
• This system is useful of classification on non-
ionic surfactants related to their behavior &
solubility in aqueous system or water.
• The numerical values, called the Hydrophile-
Lipophile Balance (HLB), denote the relative
affinity for oil & water.
• Oil soluble materials have low value & water
soluble materials have high values.

33. • On HLB assigns various numbers which vary
from 1-20.
• Numbers are calculated from saponification
values (esters) and acid value number (fatty
acid).
• Emulsifying agent with high HLB values i.e. 7
to 20 produce O/W emulsions (hydrophilic) &
those with low HLB values i.e. 3 to 6 produce
W/O emulsion (lipophilic).

34. Sr.No. Name of
Emulsifying Agent
HLB Value Type of Emulsion
1. Acacia 8.0 O/W
2. Tragacanth 13.2 O/W
3. Glyceryl
monostearate
3.8 W/O
4. Sorbitan mono-
stearate
4.7 W/O
5. Sorbitan
monooleate
4.3 W/O

35. Preparation of Emulsion
Dry gum method
Bottle Method
Wet gum method
Step involved to form Primary Emulsion
-In dry gum method the oil is first triturated with gum &
then water is added.
- In wet gum method the first gum triturated with water
to form a mucilage & then oil added in small
quantities.

36. Table shows Proportions of oil, water
& Gum acacia
Proportion of Oil : Water: Gum
Fixed Oils 4 : 2 : 1
Volatile Oils 4 : 4 : 2
Fixed Oils:- Castor oil, Cod liver oil, Shark liver oil, Olive oil, Almond oil, Liquid
paraffin.
Volatile Oils:- Turpentine oil, Sandal wood oil, Cinnamon oil, Peppermint oil

37. Dry Gum Method / Continental
Method
“4:2:1" Method
4 parts (volumes) of oils
2 parts of water
1 part of gum
In dry gum method the oil is first triturated with
gum & then water is added.

38. Wet Gum Method / English Method
4 parts (volumes) of oil
2 parts of water
1 part of gum
In wet gum method the first gum triturated with
water to form a mucilage & then oil added in
small quantities.

39. Bottle Method/ Forbes Bottle Method
• This method useful for the volatile & other
non-viscous oils.
• Because of low viscosity the volatile oils it
requires greater amount of gum.
• This method also called 4 : 4: 2 method.
• Oil is put in large bottle + Gum (shaken until
mixed) + Water (to form primary emulsion)
then volume make up with water.

40. Other Method
HOMOGENISER

41. Hand Homogeniser

42. MICROEMULSIONS
• Defined as dispersion of insoluble liquids in a
second liquid that appear clear &
homogeneous to the naked eye.
• Microemulsions are also called
 Transparent emulsion
 Solubilized system
 Micellar solution

43. • Microemulsions should not be confused,
however, with solutions formed by co-
solvency. e.g. the clear system consisting of
water, benzene, and ethanol.
• It can be prepared with emulsifying agents
which give a local negative interfacial tension
& forms monomolecular interfacial films.

44. INSTABILITY OF EMULSION
Cracking
• In cracking, separation of the disperse phase
& continuous phase.
• Cracking may be caused by any chem.,
physical or biological effect that changes the
nature of emulsifying agent or tends to make
it less stable.

45. Causes of Cracking
• Addition of opposite type of emulsifying agent:
- Monovalent soap metals produce O/W type of
emulsion & divalent soap metals produce W/O
type of emulsion.
- If monovalent soap added in divalent soap of
emulsion or divalent soap added in monovalent it
causes cracking of emulsion.

46. • Precipitation or Decomposition of Emulsifying
agent:
- Gums, Gelatin & casein are insoluble in alcohol if
this solvent is transferred to prepared emulsion,
that time the emulgent precipitate & cracking
was caused.
- Anion emulgent are incompatible with large
cations & cation emulgent are incompatible with
large anions.

47. • By addition of Common Solvent:
- If common solvent was added in prepared
emulsion that time cracking was showed.
- E.g. alcohol is added in turpentine oil liniment,
- alcohol is soluble with turpentine oil, soft soap &
water are soluble in alcohol that time destroying
the emulsion.

48. Creaming
• E.g. Milk
• Creaming may be defined as the formation of a
layer of relatively concentrated emulsion.
• Creamed emulsion may be made homogeneous
again by shaking, creaming is less serious type
of instability than cracking.
• Creaming is undesirable bec. The closeness of
the globules in the cream favours breakdown of
the interface.

49. Following are ways in which creaming may be minimised:
 Reducing the mean size & the size distribution of the globules:-
The size of the globules made either by hand or mechanical
mixer, the globule range from 1 to 50 µm, but effectively
homogenisation will reduced their diameter to form 1 to 3 µm.
 Increasing the viscosity of the continuous phase :-
- syrup & glycerin used, they changes in density betw.continuous &
dispersed phase & those are unsuitable.
- Tragacanth, sodium alginate & methylcellulose are increases
viscosity, without affecting density, useful for O/W & soft paraffin is
useful for W/O emulsion.
 Storage in cool place :-
- Temp. rise affect on viscosity. & freezing of the aqua. phase must be
avoided , ice may separate & exerting pressure on the globules,
causes cracking.

50. Phase Inversion
• It is Physical Instability
• In that changes phase O/W to W/O & vice versa.
• it causes, addition of electrolytes or changing
phase ratio or by temperature.
• It can be minimised by, proper emulsifying agent
in adequate conc. & conc. of dispersed phase
betw. 30 to 60 percent.

51. Phase Inversion Temperature formulation
(PIT/HLB temperature)
• The temperature at which the inversion occurs depends upon
emulsifier concentration is called as PIT.
• e.g. it was observed that water in benzene W/O were stabilized
with sodium stearate convert to O/W upon heating & reform
W/O emulsion upon cooling.
• Since in that formation those emulsion are prepared at
relatively high temperature & then cool at room temperature.

52. Coalescence
• Coalescence is a growth process during which the
emulsified particles join to form large particle.
• Particularly occurs in O/W systems containing
nonionic surfactants & in W/O system in which
electrical effect are negligible.
• So that reason, variety of natural gums & proteins
used at low levels & can be used at higher
concentration as primary emulsion.

53. PACKAGING
• Depending on the use, emulsions should be packed in suitable
containers.
• Emulsions meant for oral use are usually packed in well filled bottles
having an air tight closure.
• Light sensitive products are packed in amber coloured bottles.
• For viscous emulsions, wide mouth bottles should be used.
• The label on the emulsion should mention that these products have
to be shaken thoroughly before use.
• External use products should clearly mention on their label that they
are meant for external use only.
• Emulsions should be stored in a cool place but refrigeration should be
avoided as this low temperature can adversely effect the stability of
preparation.

54. EVALUATION TESTS
Determination of particle size and particle count:
It is performed by optical microscopy,
sedimentation by using Andreasen apparatus and
Coulter counter apparatus.

55. • Determination of viscosity:
For viscous emulsions, the use of penetrometer
instrument is used.

56. • Determination of phase separation:
This is another parameter used for assessing the
stability of the formulation. Phase separation may
be observed visually or by measuring the volume
of the separated phases.
• Determination of electrophoretic properties:-
Determination of electrophoretic properties like
zeta potential is useful for assessing flocculation
since electrical charges on particles influence the
rate of flocculation.
O/W emulsion having a fine particle size will exhibit
low resistance but if the particle size increase,
then it indicates a sign of oil droplet aggregation
and instability.

57. STABILITY
The stress conditions used for speeding up
instability of emulsions include:
• Centrifugal force, Agitation force Aging and
temperature
• Centrifugation: In that centrifugation at 3750
rpm in a 10 cm radius centrifuge for a period
of 5 hours is equivalent to the effect of gravity
for about 1 year.

58. • Agitation:-
In that method observing the Brownian
movement of droplets.
It is believed that no coalescence of droplet
take place unless droplets impinge upon each
other.