The document presents information on microencapsulation including definitions, reasons for microencapsulation, release mechanisms, coating materials and their properties, manufacturing techniques such as air suspension coating and coacervation, and applications. Microencapsulation is described as applying a thin coating to small particles or droplets to form microcapsules or microspheres ranging from less than one micron to several hundred microns in size. Common techniques for manufacturing microencapsulates include physical methods like pan coating and spray drying as well as chemical processes like solvent evaporation and polymerization.

1. 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 1

2. CONTENTS
• Introduction
• Reasons for Microencapsulation
• Release Mechanisms
• Coating Materials
• Coating Material Properties
• Techniques to Manufacture
• Application
• References
2

3. Introduction
Definition
“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. 3

4. 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
4

5. Release Mechanisms
1. Degradation controlled monolithic system
2. Diffusion controlled monolithic system
3. Diffusion controlled reservoir system
4. Erosion
5

6. List of coating material
Water soluble Water insoluble Wax & lipid Enteric resin
resin resin
Gelatin, Ethyl cellulose, Paraffin, Shellac,
Gum arabic, Polyethylene, Carnauba wax, Zein,
PVP, Polymethacrylate, Bees wax, Cellulose acetate
CMC, Cellulose nitrate, Stearic acid, phthalate.
Methyl cellulose, Silicones. Stearyl alcohol.
Arabinogalactan,
Polyvinyl
acrylate,
Polyacrylic acid.
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7. Coating Material Properties
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.
7

8. 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
8

9. 1. Physical Methods
1.1Air-suspension
The air suspension
process offers wide
variety of coating
material candidates for
microencapsulation.
It consist of
dispersing the solid
particulate core material
in supporting air stream
and being coated with
coating material (usually
polymeric solution)
9

10. 1.2 Coacervation phase separation
The general process consist of 3 steps under continuous agitation:
1. Formation of 3 immiscible chemical phase
2. Deposition of coating
3. Rigidization of coating.
Step: 1) Three immiscible phases are as:
a) Liquid manufacturing vehicle phase
b) Core material phase
c) Coating material phase.
Coating material phase formed by utilizing following methods:
A) Temperature change.
B) By addition of incompatible polymer
C) By non-solvent addition
D) By salt addition
E) Polymer-polymer interaction.
10

11. 1.3 Pan coating
Solid particle greater than 600 micron
size are generally consider for effective
coating.
It is used for preparation of controlled-
release beads.
Coating is applied as solution by
automized spray to desired solid core
material in coating pan.
Usually warm air is passed over the
coated material as the coating are being
applied in the coating pan.
Figure Pan coater
11

12. 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, Figure Schematic diagram of a Spray Dryer
extraction or evaporation technique. 12

13. 2.1 Solvent Evaporation
Core material
Dissolved Or Dispersed
Coating polymer solution
With Agitation
Liquid Manufacturing Vehicle Phase
Heating (If necessary)
Evaporation of Polymer solvent
Microencapsulation
13

14. 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.
14

15. 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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16. 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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