3. Introduction
Definition:
The process by which individual particals or droplets
of solid or liquid material are surrounded or coated with
continuous film of polymeric material to produce
microcapsules .
Microcapsule / Micosphere: size of particle from
micrometer to millimeter i.e. 1-1000 micrometer.
5. Advantages:
• Mask the bitter taste
• Decrease irritation
• To prevent acid degradation
• Increase solubility
• stabilisation of core material
• Hygroscopic drug is used
7. Microencapsulation
Methods
• Air suspension
• Multiorifice
CentrifugaL
• Coacervation
Phase Separation
• Pan Coating
• Solvent
Evaporation
• Spray drying and
congealing
Applicable core
material
• Solids
• Solids and liquids
• Solids and liquids
• Solids
• Solids and liquids
• Solids and liquids
Approximate
Particle size in
micrometer
• 35 -5000
• 2-5000
• 1-5000
• 600-5000
• 5-5000
• 600
Methods of Microencapsulation
8. Air suspension/wruster Process:
Microencapsulation by air suspension
method consists of the dispersing of
solids, particulate core materials in a
supporting air stream and the spray
coating on the air suspended particles
Within the coating chamber, particulate
core materials are suspended on an
upward moving air stream.
9. 2.Multiorifice Centrifugal Method:
• The Southwest Research
Institute (SWRI) has developed
this method.It is a mechanical
process for producing
microcapsules.
• Centrifugal forces are used to
hurl a core material particle
through an enveloping
microencapsulation membrane.
10. 3.Coacervation Phase separation Method:
Coacervation means the separation of a
liquid or phase when solution of two
hydrophilic colloids are mixed under
suitable conditions.
In this method, the three immiscible
phases of core material, solvent and
coating material are formed followed
by deposition of coating material on
the core.
The coating material is dissolved in a
suitable solvent and the core material
is uniformly dispersed in the solution of
the coating material.
Then the coating material is phased out
of its solution which starts getting
deposited on the particles of the core
material.
11. 4.Pan Coating Method:
Pan coating is a physical method of
preparing microencapsulation and it
can only be used for particles greater
than 600 microns in diameter.
Process of microencapsulation by pan
coating
1.Solid particles are mixed with a dry
costing material.
2.The temperature is raised so that
the coating material melts and encloses
the core particles, and then is
solidified by cooling Or the coating
material can be gradually applied to
core particles tumbling in a vessel
rather than being wholly mixed with
the core particles from the start of
encapsulation.
12. 5.Solvent Evaporation Method:
Solvent evaporation techniques are
carried out in a liquid
manufacturing vehicle (O/W
emulsion) which is prepared by
agitation of two immiscible liquids.
The process involves dissolving
microcapsule coating(polymer) in a
volatile solvent which is immiscible
with the liquid manufacturing
vehicle phase.
A core material (drug) to be
microencapsulated is dissolved
dispersed in the coating polymer
solution.
13. 6.Spray Drying And Congealing Method:
Spray Drying:
The coating solidification effected
by rapid evaporating of solvent in
whichcoating material is dissolved.
Spray Congealing:
The coating solidification is
effected by thermally congealing a
molten coating material. The
removal of solvent is done by
sorption, extraction or evaporation
technique
14. Reference:
The Theory and Practice of Industrial Pharmacy, lachman/lieberman, 4th
edition, pg no. 579-596
Microencapsulation- Processes and Applications, edited by Tan E. Vandegar,
pg no. 1-20 and 57-59
Multiparticulate drug delivery, edited by lisaac Ghebre-Sellassie, pg no. 51-
109
The Design and Manufacture of Medicines, Michael Aulton and Kevin
M.G.Taylor, 4th edition, pg no. 578-581
Polymeric Drug Delivery- Particulate Drug Carriers, edited by Sonke
Svenson, pg no. 242-245
