This document discusses emulsions and suspensions. It defines emulsions as biphasic liquid preparations containing two immiscible liquids, one dispersed as globules in the other. Suspensions are biphasic preparations with finely divided solids dispersed in a liquid vehicle. The document describes the types, formulations, evaluation and factors affecting stability of emulsions and suspensions. It also provides details of various tests to identify the types of emulsions.

1. Emulsions
&
Suspensions
Presented By
NARESH GORANTLA, M.Pharm.., (Ph.D)
Asso. Professor,
Balaji college of Pharmacy,
Anantapuramu

2. Emulsions
An emulsion is a biphasic liquid preparation
containing two immiscible liquids, one of which is
dispersed as minute globules into the others.
The liquid which is converted into minute
globules is called dispersed phase and liquid in which
the globules are dispersed is called the continuous phase

3. The emulsions are mainly of two types :-
1. Oil in water type (o/w)
2. Water in oil type (w/o)
3. Multiple emulsions
 In oil-in-water type emulsion, the oil is in
dispersed phase where as water is in continuous phase. The
o/w type emulsions are preferred for internal use
 In water-in-oil type emulsion, the water is in the dispersed
phase whereas oil is in continuous phase.
Types of Emulsions

4. 1. Dilution test
2. Dye test
3. Conductivity test
4. Fluorescence test
Tests for identification of Types of Emulsions

5.  Emulsions are diluted with water.
 If the emulsion remains stable then it is o/w emulsion.
 The w/o emulsion breaks on dilution with water as the
external phase is oil which is immiscible with water.
Dilution test

6.  Oil soluble dye – Scarlet red
 Water soluble dye – Amaranth
 Dye is mixed with a drop of emulsion and observed
under microscope.
 On addition of oil soluble dye, If the Globules appear
colored and the background remains colorless then the
emulsion is o/w type.
Dye test

7.  Water is a good conductor of electricity and oil is a poor
conductor.
 Pair of electrodes connected through low voltage bulb
and is dipped in emulsion.
 If the bulb glows on passing electric current, the
emulsion is o/w type, because the continuous phase is
water.
Conductivity test

8.  Certain fixed oils possess the physical property of
fluorescing in the presence of UV radiation.
 On microscopic observation of emulsion under UV
radiation, the whole field fluorescence indicates that oil
is in continuous phase and thus it is w/o emulsion.
 If the emulsion is o/w type then spotty fluorescence can
be seen.
Fluorescence test

9. A. Classification of emulsions in accordance to the type of
emulsifying agents used in the preparation of an emulsion
1. Emulsion containing natural gum e.g:- gum acacia, tragacanth
2. Emulsion containing gum substitute e.g:- Cellulose
3. Emulsion containing saponins
4. Emulsion containing starch
5. Emulsion containing natural waxes e.g :- woolfat and bees wax
6. Emulsion containing synthetic wax e.g:-emulsifying wax
7. Emulsion containing other emulsifying agents such as pectin.
Classification of Emulsions

10. Emulsions for oral administration :-
These are usually o/w type.
E.g:cod liver oil emulsion.
Emulsions for external use:- These may be either
o/w type or w/o type.
E.g:- oily calamine lotion
Emulsions for parenteral use:-These are used to
administer fat soluble vitamins such as A,D,E and oil
soluble sex hormones ,because there absorption in
this form is very rapid.
E.g:- cleviprex
B. Classification of emulsions in accordance to
route of administration

11. Emulsions for rectal use:-These are used in the form
of enema for the evacuation of bowel.
starch mucilage is generally used in the preparation
of enema.
Formulation of Emulsions
1. Emulsifying agents
2. Preservatives
3. Antioxidants
4. Flavours

12. The emulsifying agents reduce the interfacial tensions
between two phase i.e, oil phase and aqueous phase
and then make them miscible with each other and form
stable emulsion.
HLB scale – Hydrophile Lipophile Balance
3 – 6 indicates lipophilic properties and produces w/o emulsions.
8-18 indicates hydrophilic properties and produces o/w emulsions.
1. Emulsifying agents

13. EMULSIFYING
AGENT
NATURAL
VEGETABLE
SOURCE
ANIMAL
SOURCE
SEMI-SYNTHETIC SYNTHETIC INORGANIC ALCOHOLS
Emulsifying agents

14. Natural Emulsifying agents
from vegetable source:
1. Acacia
2. Tragacanth
3. Agar
4. Pectin
5. Starch
Natural Emulsifying agents
from Animal source:
1. Wool fat
2. Egg yolk
3. Gelatin
Semisynthetic
polysaccharides:
1. Methyl cellulose
2. SCMC
Synthetic polysaccharides:
1. Anionic: alkali soaps, metallic soaps
2. Cationic: Quart. amm compounds,
Cetrimide
3. Non-ionic: Glyceryl monostearate.
Inorganic Emulsifying
agents:
1. Magnesium oxide
2. Magnesium Al silicate
3. Bentonite
Alcohols:
1. Carbowaxes
2. Cholesterol: Cetyl alcohol, Stearyl
alcohol, Cholesterol
3. Lecithins

15. B. Preservation of emulsions:- Emulsions which are prepared
by using emulsifying agents such as carbohydrates, proteins may
lead to the growth of bacteria, fungi in the presence of water.
In order to preserve emulsion properly:-
Benzoic acid (0.1-0.2%)
Methyl paraben and propyl paraben (0.1-0.2%)
Chloroform (0.25%)
Cetrimide (0.002-0.01%)
C. Antioxidants :- During storage of emulsions the fats
and emulsifying agents under go oxidation by
atmospheric oxygen. This can be avoided by using
antioxidants such as
Gallic acid and Ascorbic etc.
D. Flavors :- To increase the palatability
Vanallin and Benzaldehyde.

16. Stability of emulsions
 An emulsion remain to be sable if it remains as such
after its preparation i.e. the dispersed phase globules
remain distributed uniformly during storage.
The following three changes occurs usually during
the storage of an emulsion.
1. Cracking
2. Creaming
3. Phase inversion

17. Cracking:
 Separation of two layers of disperse and continuous
phase due to coalescence of disperse phase and is
difficult to redisperse.
 The Reasons include:
1. Addition of Emulsifying agent of opposite type.
2. Decomposition or ppt of Emulsifying agent.
3. Addition of a common solvent.
4. Microorganisms.
5. Change in temperature.
6. Creaming.

18. Creaming:
 Upward moment of dispersed phase globules to form a
thick layer at the surface.
 Creaming is reversible and the emulsion can regain its
structure on shaking.
 Stokes law:
 The factors include:
1. Radius of globules
2. Difference in the densities
3. Viscosity of the dispersion medium
4. Storage condition

19. Phase inversion:
 Change of one type of emulsion into the other type i.e.
o/w type changes to w/o emulsion.
 The Reasons include:
1. Addition of Electrolyte
2. Changing the phase volume ratio
3. Changing the emulsifying agent
4. Change in temperature.

20. SUSPENSIO
NS

21. Suspensions
Suspensions are the biphasic liquid dosage form of
medicament in which the finely divided solids particles
ranging from 0.5 to 5.0 micron are dispersed in a liquid
vehicle.
The particle size of disperse phase is very important in the
formulation of suspensions.
Qualities of a Good suspension
1. It should settle slowly and should be readily re-dispersed on
gentle shaking of the container
2. It should be chemically inert.
3. The suspended particles should not form a cake.
4. The suspension should pour readily and evenly from its container.

22. Classification of suspensions
Suspensions are classified into four main classes
according to the pharmaceutical use:-
1. Oral Suspensions e.g :- Tetracycline HCL
2. Parenteral Suspensions e.g:- procaine pencilline G
3. Ophthalmic Suspensions e.g:- 2-amino butanol
4. Suspensions for external use e.g;- calamine lotion

23. FORMULATION
1. Flocculating agents
2. Thickening agents / Suspending agents
A. Polysaccharides
B. Inorganic agents
C. Synthetic compounds
3. Wetting agents
4. Preservatives
5. Organoleptic additives

24. Formulation of suspensions :-
1. Flocculating agents:-
• In suspensions the solids particles are
well dispersed into dispersion
medium i.e vehicle.
• The dispersion can be improved by
adding a surfactant or protective
collides which acts as flocculating agents .
• The flocculating agents acts by reducing the surface
tensions and thereby improving the dispersions of solids
and causes flocculation.
E.g:- sodium lauryl sulphate, tweens, spans etc.

25. 2. Thickening agents:-
• These are hydrophilic colloids which form colloidal
dispersions with water, and
• increase the viscosity of the continuous phase, so that
the solid particle remains suspended in it for a sufficient
long time.
The thickening agents used to stabilise suspensions are
classified into three major groups
A. Polysaccharides
B. Inorganic agents
C. Synthetic compounds

26. A. Polysaccharides:
Natural polysaccharides
1. Gum Acacia
2. Tragacanth
3. Starch
4. Sodium alginate: 1 %
Semisynthetic polysaccharides
1. Methyl cellulose: 2 %
2. SCMC: 0.25 to 1 %
3. MCC
B. Inorganic agents
1. Clay: Bentonite and Al.Mg Silicate
2. Aluminium hydroxide
C. Synthetic compounds:
1. Carbomer: 0.1 to 0.4 %
2. Colloidal silicon dioxide: 1.5 to 4 %

27. 3. Wetting agents:-
• These are the substances which reduce the
interfacial tensions between the solid particles
and liquid medium.
• wetting agents can be absorbed at solid or liquid
interface in such a way that the affinity of the
particles for the surrounding medium is increased
and the interparticular forces are decreased.
• Eg: Alcohol, Glycerine and polysorbate.

28. 4. Preservatives:-
• A suitable preservative is needed to preserve suspensions
against bacterial growth.
• Preservative selected should be effective against a wide
range of microorganism.
Benzoic acid, sodium benzoate, methyl paraben
5. Organoleptic additives:-
• Colouring agents, sweetening agents and flavouring
agents are generally incorporated in oral
suspensions.

29. EVALUATION OF SUSPENSIONS
1. Sedimentation methods
2. Rheological methods
3. Electrokinetic methods
4. Micromeritic methods
1. Phase separation
2. Rheological methods
3. Electrokinetic methods
4. Micromeritic methods
EVALUATION OF EMULSIONS

30. 1. Sedimentation method :-
 The measurement of sedimentation volume is the most
important parameter in the evaluation of the stability of
suspensions.
 The suspension was made separately into 100ml measuring
cylinder and sedimentation volume was read after At
weakly intervals for 12 weeks.
Sedimentation volume, F = Hu/Ho
Where, Hu = Ultimate height,
Ho = Initial height

31. 1. Phase separation for emulsions:-
 Phase separation in a emulsion may be due to creaming
or coalescence of globules.
 The rate and degree of phase separation can be
determined by keeping a certain amount in a measuring
cylinder and the volume of separated phase can be
measured at different time intervals.
 One more method is to collect samples of the emulsion
from the top and bottom of the emulsion after some
period of storage.
 Comparing the samples by appropriate analytical
techniques for
 Water content and
 Oil content gives information about the contents.

32. 2. Rheological methods :-
• Rheology is the study of viscosity.
• Rheological study of the suspensions provide
information about settling behaviour as the
sedimentation depends on the viscosity of the
dispersion medium.
• A decrease in the viscosity of the suspension results
in the settling of the dispersed phase particles.
Brookfield viscometer

33. 3. Electrokinetic methods:-
• The measurement of surface charge of the suspension is
the basis of electrokinetic methods.
• Zeta potential is the surface electric charge and is a
measure of extent of repulsion between particles.
• Measurement of Zeta potential using micro
electrophoresis apparatus and zetaplus it shows the
stability of dispersed system.
Micro electrophoresis apparatus Zeta plus apparatus

34. 4. Micrometric methods:-
• The stability of suspension depends on the particle size
of the dispersed phase.
• Any change in the particle size with time leads to an
instable suspension.
• Determination of particle size of dispersed phase
particles will provide useful information regarding the
stability of a suspensions.
• Two methods:
• Stage micrometer
• Coulter counter.