2. IINNTTRROODDUUCCTTIIOONN
Emulsions may be described as heterogenous systems,
where one immiscible liquid is dispersed in another in
the form of droplets and stabilized by a third component
called emulsifying agent
The emulsions can be divided up into:
1. Oil in water (O/W) emulsions and
2. Water in Oil (W/O) emulsions.
1. O/W Emulsion:
By dispersion of oil into water the oil drops are the
inner, dispersed phase. Water is the outer, continuous
phase.
3. 2. W/O Emulsion:
By dispersion of water into oil the water
drops are the
Inner, dispersed phase. Oil is the outer,
continuous phase.
Oil phase
Aq phase
Oil phase
4. MMUULLTTIIPPLLEE EEMMUULLSSIIOONNSS::
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.
5. This is made possible by double emulsification
hence the systems are also called as
“Double emulsions”.
These are also called as “Liquid membrane
systems” as the liquid film which separates the
liquid phases acts as a thin semipermeable film
through which solute must diffuse in order to
transverse from one phase to another.
Multiple emulsions are thermodynamically
unstable.
They are often stabilized by using a
combination of hydrophilic & hydrophobic
surfactants.
The ratio of these surfactants is important in
achieving stable multiple emulsions.
6. TTYYPPEESS::
With optical microscopy method,
multiple emulsions are classified as,
1. coarse (>3 micrometer in diameter)
2. Fine (1-3 micrometer in diameter)
3. Micro-multiple emulsions
(<1 micrometer in
diameter)
10. Multiple emulsions can also be ffoorrmmuullaatteedd bbyy uussiinngg eeiitthheerr
oo11//oo22//oo11 ssyysstteemmss oorr oo11//oo22//ww ffoorrmmuullaattiioonnss aarree ppoossssiibbllee..
EExxaammpplleess ooff bbootthh aarree sshhoowwnn iinn FFiigguurree
11. 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 continuous
phase.
12. EEMMUULLSSIIFFYYIINNGG AAGGEENNTTSS
Emulsifier or surface active agent [SAA] is
molecule which has two parts, one is
hydrophilic and the other is hydrophobic. Upon
the addition of SAA, it tends to form
monolayer film at the oil/ water interface.
15. MMeecchhaanniissmm ooff rreelleeaassee ooff ddrruugg::
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.
20. AAPPLLLLIICCAATTOONNSS OOFF MMUULLTTIIPPLLEE
EEMMUULLSSIIOONNSS
Multiple emulsions finds wide range of
applications in controlled or sustained drug
delivery, targeted delivery, taste masking,
bioavailability enhancement, enzyme
immobilization, etc.
It will be able to provide a novel carrier system
for drugs, cosmetics and pharmaceutical agents.
21. 1. Hemoglobin multiple emulsion having specified
properties is suitable for provision of oxygen as a
blood substitute and other oxygen transfer processes.
2. W/O/W multiple emulsions are systems of potential
interest in the oral administration of insulin.
Although it has been shown that a single oral
administration of insulin-loaded W/O/W multiple
emulsion to diabetic rats led to the significant
decrease of blood glucose.
3. (w/o/w) multiple emulsions and polymeric
nanoparticle formulations containing influenza virus
surface antigen hemagglutinin (HA) are thought to
be suitable carriers for a vaccine delivery system.
22. 4. Using a water-in-oil-in-water multiple emulsion
system developed for pulmonary drug targeting,
the effectiveness of tetrandrine as an antifibrotic
agent.
5. To develop a prolonged and sustained
release preparation , an albumin micro-sphere-in-
oil-in-water emulsion was prepared.
Tegafur was used as a model drug.
6. Vitamin c has been widely used in
formulations of skin care products.
7. Multiple emulsions are also used in topical
application ex… a w/o/w emulsion of
Metronidazole.
23. RREEFFEERREENNCCEESS
1) Pharmaceutical Emulsions and Suspensions, edited by Francoise
Nielloud Gilberte Marti-Mestres.
2) Pharmaceutical Dosage Forms: Disperse systems, vol.3, second
edition, Edited by Herbert A.Liberman, Martin M. Rieger and
Gilbert S. Banker.
3) some studies on Multiple Emulsions by G.Vishwanadham, (Ph.D
thesis, KU)
4) Advances in Controlled and Novel Drug Delivery Systems,
Edited by N.K. Jain.
5) Targeted and controlled Drug Delivery Novel Carrier Systems
by -S.P. Vyas and R.K. Khar.
http://www.aapsj.org/view.asp
http://www.blackwell-synergy.com
http://www.rsc.org/delivery/_ArticleLinking
http://cat.inist.fr
http://iufost.edpsciences.org
