Microencapsulation

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A
Presentation
On
Microencapsulation
By
Mr. Ghodake Chaitanya A.
Under the Supervision of
Mr. N. A. Guajrathi
Assistant Professor
P.S.G.V.P.M’S COLLEGE OF PHARMACY,
DEPARMENT OF PHARMACEUTICS,
SHAHADA, DISTRICT- NANDURBAR
MAHARASHTRA.
2011- 2012

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CONTENTS
•Introduction
•Reasons for Microencapsulation
•Release Mechanisms
•Coating Materials
•Coating Material Properties
•Techniques to Manufacture
•Application
•References

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“Microencapsulation may be defined as the process of
surrounding or enveloping one substance within another
substance on a very small scale, yielding capsules ranging
from less than one micron to several hundred microns in size.”
•It is mean of applying thin coating to small particle of solid or
droplet of liquid & dispersion.
•Particle size: 50-5000 micron.
•2 phases: a) Core material
b) Coating material
•Also known as microcapsule, microsphere, coated granules,
pellets.
Introduction
Definition

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Reasons For Microencapsulation
For sustained or prolonged drug release.
For masking taste and odor of many drugs to improve
patient compliance.
For converting liquid drugs in a free flowing powder.
To reduce toxicity and GI irritation
Incompatibility among the drugs can be prevented by
microencapsulation.
The drugs, which are sensitive to oxygen, moisture or light,
can be stabilized by microencapsulation

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Release Mechanisms
1.Degradation controlled monolithic system
2. Diffusion controlled monolithic system
3. Diffusion controlled reservoir system
4. Erosion

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List of coating material
Water soluble Water soluble
resinresin
Water insoluble Water insoluble
resinresin
Wax & lipidWax & lipid Enteric resinEnteric resin
Gelatin,Gelatin,
Gum arabic,Gum arabic,
PVP,PVP,
CMC,CMC,
Methyl cellulose,Methyl cellulose,
Arabinogalactan,Arabinogalactan,
Polyvinyl Polyvinyl
acrylate,acrylate,
Polyacrylic acid.Polyacrylic acid.
Ethyl cellulose,Ethyl cellulose,
Polyethylene,Polyethylene,
Polymethacrylate,Polymethacrylate,
Cellulose nitrate,Cellulose nitrate,
Silicones. Silicones.
Paraffin,Paraffin,
Carnauba wax,Carnauba wax,
Bees wax,Bees wax,
Stearic acid,Stearic acid,
Stearyl alcohol.Stearyl alcohol.
Shellac,Shellac,
Zein, Zein,
Cellulose acetate Cellulose acetate
phthalate.phthalate.

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1. Stabilization of core material.
2. Inert toward active ingredients.
3. Controlled release under specific conditions.
4. Film-forming, pliable, tasteless, stable.
5. Non-hygroscopic, no high viscosity, economical.
6. Soluble in an aqueous media or solvent, or melting.
7. The coating can be flexible, brittle, hard, thin etc.
Coating Material Properties

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Techniques To Manufacture
1. Physical methods
1.1 Air-suspension coating
1.2 Coacervation Process
1.3 Pan coating
1.4 Spray–drying
2. Chemical process
2.1 Solvent Evaporation
2.2. Polymerization

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1. Physical Methods
1.1Air-suspension
The air suspension The air suspension
process offers wide process offers wide
variety of coating variety of coating
material candidates for material candidates for
microencapsulation.microencapsulation.
It consist of It consist of
dispersing the solid dispersing the solid
particulate core material particulate core material
in supporting air stream in supporting air stream
and being coated with and being coated with
coating material (usually coating material (usually
polymeric solution)polymeric solution)

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1.2 Coacervation phase separation
The general process consist of 3 steps under continuous agitation:The general process consist of 3 steps under continuous agitation:
1.1.Formation of 3 immiscible chemical phaseFormation of 3 immiscible chemical phase
2.2.Deposition of coatingDeposition of coating
3.3.Rigidization of coating.Rigidization of coating.
Step: 1) Three immiscible phases are as:Step: 1) Three immiscible phases are as:
a) Liquid manufacturing vehicle phase a) Liquid manufacturing vehicle phase
b) Core material phaseb) Core material phase
c) Coating material phase.c) Coating material phase.
Coating material phase formed by utilizing following methods:Coating material phase formed by utilizing following methods:
A) Temperature change.A) Temperature change.
B) By addition of incompatible polymerB) By addition of incompatible polymer
C) By non-solvent additionC) By non-solvent addition
D) By salt additionD) By salt addition
E) Polymer-polymer interaction. E) Polymer-polymer interaction.

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Solid particle greater than 600 micron Solid particle greater than 600 micron
size are generally consider for effective size are generally consider for effective
coating.coating.
It is used for preparation of controlled- It is used for preparation of controlled-
release beads.release beads.
Coating is applied as solution by Coating is applied as solution by
automized spray to desired solid core automized spray to desired solid core
material in coating pan.material in coating pan.
Usually warm air is passed over the Usually warm air is passed over the
coated material as the coating are being coated material as the coating are being
applied in the coating pan.applied in the coating pan.

1.3 Pan coating1.3 Pan coating
Figure Pan coaterFigure Pan coater

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1.4 Spray Drying and Spray Congealing
Spray Drying:
The coating solidification effected by
rapid evaporating of solvent in which
coating 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.
Figure Schematic diagram of a Spray Dryer

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Core material
Dissolved Or Dispersed
Coating polymer solution
With Agitation
Liquid Manufacturing Vehicle Phase
Heating (If necessary)

Evaporation of Polymer solvent
Microencapsulation
2.1 Solvent Evaporation

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2.2 Polymerization
•The method involve the reaction of monomeric unit located at
the interface existing between a core material substance and
continuous phase in which the core material is disperse.
•The core material supporting phase is usually a liquid or gas,
and therefore polymerization reaction occur at liquid-liquid,
liquid-gas, solid-liquid, or solid-gas interface.
•E.g. In the formation of polyamide (Nylon) polymeric reaction
occurring at liquid-liquid interface existing between aliphatic
diamine & dicarboxylic acid halide.

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Application
To improve the flow properties. e.g. Thiamine, Riboflavine
To enhance the stability. e.g. Vitamins
To reduce the volatility of materials. e.g. Peppermint oil,
Methyl salicylate
To avoid incompatibilities. e.g. Aspirin and
Chloramphenicol
To mask the unpeasant taste and odour. e.g. Aminophylline,
castor oil
To convert liquids into solids. e.g. Castor oil, Eprazinone,
To reduce gastric irritation. e.g. Nitrofurantoin,
Indomethacin

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REFERENCE
1.Leon, Lachman, Herbert A. L., Joseph, L. K;
“ The Theory And Practice Of Industrial
Pharmacy”, 3rd edition, 1990, Varghese
Publishing House,412, 428.
2.Microencapsulation encyclopedia of
polymer science and technology, 2005 John
Wiley & Sons, 1-3.
3.Microencapsulation: a review international
journal of pharmaceutical sciences review
and research volume 1, issue 2, marches –
April 2010.
4.Jackson, L. S., Lee. K., (1991-01-01),
“Microencapsulation and the food industry”
(htm) Lebennsmittel-Wissenschaft
Techonologie. Rerrived on 1991-02-02.
5.Youan, B. C., Hussain, A., Nguyen, N.T.,
“AAPS Pharma Sci.”, 2003, 5(2).

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