Microemulsions are thermodynamically stable, transparent mixtures of oil, water, and a surfactant (and sometimes a co-surfactant) that form spontaneously without requiring additional energy input, exhibiting unique properties and applications in various fields.

1. Microemulsion :
A novel drug carrier system
Guided by : Dr Sachin Rathod
Asst Professor
Presented by : Y Subhasish Singha
MPharm (IP) 1st semester

2. Agenda Overview
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INTRODUCTION
HISTORY
MICROEMULSION TYPES
PREPARATION METHODS
EQUIPMENTS USED
INFLUENTIAL FACTORS
EVALATION PARAMETERS
APPLICATIONS

3. INTRODUCTION
Microemulsions are thermodynamically stable, isotropic systems composed of
water and oil phases mixed with a surfactant, often combined with a co-
surfactant. The co-surfactant, typically a short- to medium-chain alcohol,
reduces the interfacial tension between the two immiscible phases, allowing
the formation of microemulsions with droplet sizes ranging from 10 to 140 nm.
These unique properties make microemulsions highly effective for drug
delivery, particularly in topical applications. Their low viscosity, transparency,
and ability to solubilize poorly soluble drugs enhance the delivery of active
agents into the skin, improving solubilization and bioavailability compared to
conventional vehicles like lotions or creams.

4. HISTORY
The microemulsion concept was introduced as early as 1940's by
Hoar and Schulman who generated a clear single-phase solution
by titrating a milky emulsion by hexanol.
Schulman and co-worker (1959) subsequently coined the term
microemulsion.
In the year 1970, research in microemulsion reached on a larger
scale.

5. W h a t i s M i c r o e m u l s i o n ? ? ?
Micro-emulsion is homogenous,
transparent, thermodynamically
stable dispersions of water and
oil, stabilized by a surfactant,
usually in combination with a
co-surfactant."

6. Microemulsions are small scale versions
of emulsion.
The droplet sizes are very small,
typically 100 Å which is about 100 times
smaller than typical emulsion droplet
sizes.
Fig : Microemulsion structure

7. ALTERNATIVE NAMES :
Microemulsions are also called as
Transparent emulsion
Swollen micelle
Micellar solution
Solubilized oil

8. Microemulsion in our life

9. ADVANTAGES OF MICROEMULSIONS
These are thermodynamically stable.
Require minimum energy for formation.
Ease of manufacturing.
Improved drug solubilization and bioavailability.
Wide applications in colloidal drug delivery systems.
The formation of microemulsion is reversible.
Improve the efficacy of a drug & Minimum side effects.

10. • Use of large concentration of surfactant and co-surfactant
necessary for the stabilizing micro droplets.
• Limited solubilizing capacity for high melting substances.
• Microemulsion stability is influenced by environmental parameters
such as, temperature & pH. These parameters change upon
microemulsion delivery to the patients.
DISADVANTAGES OF MICROEMULSIONS

11. Feature Microemulsions Traditional Emulsions
Droplet Size 10-200 nm 1-20 µm
Appearance Clear or translucent Cloudy or opaque
Preparation Low energy input, can form spontaneously
High energy input required (e.g., high shear
mixing)
Stability Generally more stable due to smaller droplets
Less stable, as larger droplets can coalesce
over time
Surfactant Requirement
Typically requires surfactants and co-
surfactants for stabilization
Surfactants are used, but the system is less
delicate
Form
Can form in a single phase (oil and water
mixed)
Requires separate oil and water phases
Comparison between microemulsions and traditional emulsions

12. E M U L S I O N MICROEMULSION

13. Microemulsions are of 3 types. They are :
O/W Microemulsion
W/O Microemulsion
Bi-continuous microemulsion

14. O/W Microemulsion where in droplets are dispersed in the
continuous aqueous phase.
W/O Microemulsion where in water droplets are dispersed in the
continuous oil phase.
Bi-continuous microemulsion where in micro domains of oil &
water are inter dispersed within the system.
In all the three types of microemulsions, the interface is stabilized
by an appropriate combination of surfactants and/or co-
surfactants.

15. PREPARATION METHODS OF MICROEMULSIONS :
Following are the different methods used for the
preparation of the microemulsions :
1) Phase titration method
2) Phase inversion method

16. PHASE-TITRATION METHOD :
Dilution of an oil-surfactant mixture with water. [W/O]
Dilution of a water surfactant mixture with oil.[O/W]
Mixing of all components at once, in some systems, the
order of ingredients addition may determine whether a
microemulsion forms are not.

17. PHASE-INVERSION METHOD :
Temperature range in which an o/w microemulsions inverts to a w/o
type.
• Using non-surfactants: polyoxyethylene are very susceptible to
temperature. With increase in the temperature, polyoxyethylene group
becomes dehydrated, altering critical packing parameter which results
in the phase inversion.
• For ionic surfactants: increasing temperature, increase the
electrostatic repulsion between the surfactant headgroups thus causing
reversal of film curvature. Hence, the effect of temperature is opposite
to the effect seen with non-ionic surfactants.

18. EQUIPMENTS USED
Colloidal Mill
It is a machine that reduces the size
of particles in a liquid or the size of
droplets in an emulsion. It uses a
high-speed rotor to push a fluid
through small holes in a stationary
stator. The size of the holes can be
adjusted to control the level of
shear, which determines the size of
the resulting particles.

19. A rotor-stator mill, also known as a
rotor-stator mixer, is a device that uses
a rotating rotor and a stationary stator
to mix, disperse, and homogenize
materials
Rotor-stator

20. HOMOGENIZER
Homogenizer is a mixer used to
create a uniform and even mixture
by forcing material through a
narrow, confined space.

21. BRAND NAME DRUG COMPANY DOSAGE FORM CATEGORY
Douxoseborrhea Phytosphingosine Sogeval Spray Emollient
Retamax Retinol Skin Health inc Cream Emollient
White glow SPF25 Lotus Herbal Cream Emollient
Tray bell Cocoa extract Alcantra Shampoo Cleansing
MARKETED PREPARATIONS

22. Factors affecting microemulsion formation
PACKING RATIO
PROPERTY OF SURFACTANT
PROPERTY OF OIL PHASE
TEMPERATURE
CHAIN LENGTH
NATURE OF CO-SURFACTANT

23. EVALUATION PARAMETERS STUDIES :
Phase behaviour
Size and shape
Rheology
Conductivity
Zeta potential
Drug release studies
Physical stability study

24. Applications of Microemulsion
Oral bioavailability enhancement poorly water soluble drugs
Protection against Biodegradation
Solid State formulation
Supersaturable Microemulsion System
Ocular Drug delivery System
Parenteral Drug Delivery System
Topical Drug Delivery System
Mucosal Drug Delivery System
Transdermal Drug Delivery System

25. CONCLUSION :
Microemulsions are potentially quite powerful alternative carrier system
for delivery because of high solubilization capacity, transparency,
thermodynamic stability, ease of preparation, and high diffusion and
absorption rates through skin, when compared to solvent without the
surfactant system.
A number of factors must be considered when using microemulsions as
drug delivery system such as surfactant, co-surfactant, oils, PH, HLB,
temperature etc.

26. REFERENCES :
• The Theory and practice of Industrial pharmacy., Leon
Lacham, Herbert A.Liberman special Indian edition 2009,pg.no:
507-530.
• Shaji,J.,Reddy, M.S.; Microemulsion as drug delivery
system,Pharma Times,
• Razdan,R.,Devarajan,P.V.; Microemulsions Indian Drugs,
2003,pg.no: 139-146.

27. Thank You