MULTIPLE EMULSION & SUBMICRON EMULSION
Jony Mallik
M.Pharm
CONTENT
1) Definitio of Emulsion.
2) What is multiple emulsion?
3) What is emulsifing agent?
4) Mechanism of drug release.
5) Equipments used in emulsion preparation.
6)
Application
7) What is Microemulsion?
8) Characteristics of microemulsion.
9) Advantage , Disadvantage & Application of microemulsion.
EMULSION
DEFINATION:”emulsion is a thermodynamically unstable mixture of two
immiscible liquids.”
TYPES:
Micro(transperent)
O/W
W/0
O/W/O
W/O/W
=water phase
=oil phase
Multiple emulsion are complex system which consist of both w/o and o/w
at the same time.
There are potential matrices for the encapsulation of biactive compounds
and for the controlled release compounds
w/o/w multiple emulsion are system where small water droplets are
entrapped within larger oil droplets and they are disperse continous water
phase
Because of presense of reseroir phase that can be use to prolong release of
active ingredients.
Multiple emulsion w/o/w contain two emulsifiers:
1 Low HLB surfactant (Hydrophobic in nature)
2 High HLB surfactant (Hydrophilic in nature)
Low HLB surfactant use in disperse phase
High HLB surfactant use in continous phase.
MULTIPLE EMULSION
HYDROPHILIC SURFACTANT
HYDROPHOBIC SURFACTANT
W/O/W SYSTEM
=water phase
O/W/O SYSTEM
=oil phase
surfactants
Non ionic
Anionic
Sodium oleate
Pottasium oleate
Glyceryl monostearate
cationic
Benzalkonium chloride
span 80
span20
Tween 20
Tween 60
Tween 80
Mechanism of release of drug:
 Two type inter phase in w/o/w multiple emulsion
1 Primary interface lying between the inner w/o phase contains the low
HLB surfactant.
2 Secondary interface lying between droplets and continuous aqueous phase. Low and
high HLB surfactant present in it. When hydrophilic surfactant in the continuous
aqueous phase exceed its critical micelle concentration the resultant micelles may
solubilize the hydrophobic surfactant present in oil phase.
 Resulting in a decrease in the hydrophobic surfactant concentration and rupture the oil
layer and lose of internal aqueous phase.
METHOD OF PREPARATION
1) Solvent evaporation method
2) Two step emulsification.
3) Phase inversion technique.
SOLVENT EVAPORATION
TECHNIQUE
EQUIPMENTS
To electric motor
shaft
Impeller/blade
Mechanical stirrer
MECHANICAL
STIRRES
•Impellers mounted on a
shaft.
•Paddles or blade is used.
•Degree of agitation is
controlled by speed but
liquid flow pattern is by
type of impellers.
inlet
Vibrating blade
Nozzle jet
ultrasonifiers
outlet
ULTRASONIFIERS
•Use ultrasonic enegry
for emulsification.
HOMOGENIZR
outlet
(500 to 5000psi)
spring
Small orifice
inlet
homogenizer
•Forcing liquid mixture
through small orifice at
very high pressure.
•Yiled emulsion of very
low particle size(1nm).
APPLICATION
• In theory, multiple emulsions have significant potential for breakthrough applications in
food, agricultural, pharmaceutical, nutraceutical, and cosmetic industries in which they can
facilitate the sustained release and transport of active material.
• In cosmetics, these systems can prevent degradation of an active ingredient and release it
at a controlled rate.
• They can also improve dissolutions or solubilization of insoluble materials.
• Due to these properties, multiple emulsions find applications related to protecting sensitive
and active molecules such as vitamins C and E from the external phase—a process called
antioxidation.
Microemulsions
Microemulsions are thermodynamically stable, optically transparent,
isotropic dispersions of aqueous and hydrocarbon liquids stabilized
by an interfacial film of surfactant molecules
Microemulsions are monodispersed spherical droplets (diameter <
100 nm) of water in oil or oil in water, depending on the nature of the
surfactant.
Microemulsions and (Macro) emulsions are Different
Microemulsion
Macroemulsion
Thermodynamically Stable
Kinetically Stable
Droplet size 10 - 100 nm (transparent)
1-10 m (opaque)
High surface area: 200 m2/g
Low surface area: 15 m2/g
Ultra Low O/W IFT (10-2 – 10-3 mN/m)
O/W IFT 1-10 mN/m
W/O , O/W and Bicontinuous types
W/O or O/W types
MODERN EQUIPMENTS
Bitumen-emulsion system UVB-14
Inline homogenizer
Vacuume emulsifier
Vacuume emulsifier for
Eye ointment and creams.
Intake homogenizer