This document defines an emulsion as an unstable system consisting of at least two immiscible liquid phases, one dispersed as globules in the other. Emulsions can be oil-in-water or water-in-oil, with particle sizes typically ranging from 0.1 to 100 μm. Emulsifying agents help stabilize emulsions by forming monomolecular or multi-molecular films at the oil-water interface to prevent globule coalescence. Common emulsifying agents include surface-active agents, hydrophilic colloids, and finely divided solids. The HLB system assists in selecting emulsifying agents based on their hydrophilic-lipophilic balance. Pharmaceutical applications of emulsions include

1. EMULSION

2. PRESENTED BY:
 AREEBA SHAHID
 FARAH NAZ
 BUSHRA DAR
 MARINA MURAD
 JAWARIA NIAZ KHAN

3. DEFINITION:
An emulsion is a thermodynamically unstable
system consisting of at least two immiscible liquid
phases one of which is dispersed as globules in the
other liquid phase, stabilized by a third substance
called emulsifying agent.
Particle Size
The particle size
of the dispersed
phase commonly
ranges from 0.1 to
100 μm.

4.  The dispersed liquid is known as the Internal , Discontinuous Or
dispersed phase.
 The droplet phase is called the dispersed phase or internal phase.
 Whereas the dispersion medium is known as the External or
Continuous phase
 The liquid in which droplets are dispersed is called the external or
continuous phase.
Internal Phase & External Phase:

5. Internal Phase & External Phase:

6. OIL-IN-WATER EMULSION:
• Oil phase dispersed in water
WATER-IN-OIL EMULSION:
• Water phase dispersed in oil
EMULSION TYPES:

7. General Types of Pharmaceutical Emulsions:
Vitamin
drops
Lotions
Liniments
Creams
Ointments
Emulsions

8. 1) Dilution Test:
based on the solubility of external phase of
emulsion.
- o/w emulsion can be diluted with water.
- w/o emulsion cannot be diluted with oil.
Methods to determine type of emulsion:
Few drops
of emulsion
Few drops
of water Water distribute
uniformly
Water separate
out as layer
O/W emulsion
W/O emulsion

9. Methods to determine type of emulsion:
Electrode
Bulb
Emulsion
= Bulb glows with O/W
= Bulb doesn’t glow with W/O
2)Conductivity Test:
Water is good conductor of electricity
whereas oil is non-conductor.

10. 3)Dye-Solubility Test:
 Water-soluble dye will dissolve in the aqueous
phase.
 Oil-soluble dye will dissolve in the oil phase.
4)Fluorescence test:
Oils give fluorescence under UV light, while water
doesn’t. Therefore, O/W emulsion shows spotty
pattern while W/O emulsion fluoresces.
Methods to determine type of emulsion:

11. EMULSIFYING AGENTS:
Emulsifying agents is a substance that help
an emulsion become more stable. They are
added to an emulsion to prevent the
coalescence of the globules of the dispersed
phase.

12. Types of emulsifying agents:
1) Surface active agent: adsorbed at oil/water
interface to form monomolecular film to reduce
the interfacial tension
2) Hydrophilic colloids: forming a
multimolecular film around the dispersed droplet
3) Finely divided solid particles: they are
adsorbed at the interface between two
immiscible liquid phases to form a film of
particles around the dispersed globules.

13. 1
Synthetic
Surface active agents
( Monomolecular
films)
2
Semi synthetic and
natural
Hydrophilic colloids
( Multi-molecular films)
3
Finely divided solid
particles
( Particulate film)
Types of emulsifying agents:

14. Monomolecular films:
Emulsifying agents with stabilizing
action form monolayer at the oil-
water interface. This monolayer
prevents coalescence of droplets.
The functions of surface active agents
to provide stability to dispersed
droplets are as following:
• Reduction of the interfacial tension.
• Form coherent monolayer to prevent
the coalescence of two droplets when
they approach each other.
• Provide surface charge which cause
repulsion between adjust particles.
Mechanism of emulsifying agent:
e.g.
•Sorbitan monooleate
•Polyoxyethylene
sorbitan monooleate

15. Mechanism of emulsifying agent:
Multi molecular films:
Multi molecular films around the
droplets of dispersed phase are formed
by hydrophilic colloids. They act as
coats around the droplets making them
highly resistant to coalescence.
Hydrophilic colloids form multi
molecular 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. They have, also,
an auxiliary effect by increasing the
viscosity of dispersion medium.
e.g.
•Acacia
•Gelatin

16. Solid particle films:
Small solid particles like that
are wetted to some degree by
both oil and water can act as
emulsifying agents. This results
from their being concentrated
at the interface, where they
produce a particulate film
around the dispersed droplets
to avoid coalescence
Particles that are wetted
preferentially by water from
o/w emulsion, whereas those
wetted more by oil form w/o
emulsion.
Mechanism of emulsifying agent:
e.g.
Bentonite
Veegum

17. Selection of Emulsifying Agents
using HLB method
A system was developed by William C. Griffin to assist
making systemic decisions about the amounts and types
of surfactants needed in stable products. The system is
called the HLB (hydrophile-lipophile balance) system.
HLB RANGE USE
0-3 Antifoaming agents
4-6 W/O emulsifying agent
7-9 Wetting agents
8-18 O/W emulsifying agent
13-15 Detergents
10-18 Solubilizing agents

18. 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 lipophillic
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.

19. 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.

20. HLB values of some common
emulsifying agents
Emulsifying Agent HLB Value
Acacia: 8
Polysorbate 20neewT(20:) 16.7
Polysorbate 60neewT( :60:) 14.9
Polysorbate 80neewT(80:) 15
Oleic acid: 4.3
Sorbitan monolaurate (Span 20:) 8.6
Sorbitan monolaurate (Span 60:) 4.7
Sorbitan monolaurate (Span 80:) 4.3

21. To mask the taste
pharmaceutical application of emulsion:
O/W emulsion facilitates the absorption of
water-insoluble compounds comparing to their oily
solution preparations (e.g. vitamins)
Emulsion can be used for external
application in cosmetic and
therapeutic uses.