Microencapsulation involves coating active ingredients with thin polymer shells to protect them. There are several methods for microencapsulation including physicomechanical methods like pan coating and spray drying, physicochemical methods like ionotropic gelation and coacervation, and chemical methods like solvent evaporation and polymerization. Microencapsulation has advantages like masking tastes, converting liquids to powders, and enabling controlled release, but also has disadvantages like higher costs and potential stability issues. Common encapsulation methods include spray drying, pan coating, solvent evaporation, and interfacial polymerization.

1. Microencapsulation
Introduction,
Advantages and
disadvantages,
Methods of
encapsulation
- Snehal Jagtap

2. Introduction -
Definition : “Microencapsulation
is a process in which active
substances are coated by
extremely small capsules.”
“Microencapsulation is a
process by which solids, liquids
or even gases can be enclosed
in microscopic particles by
formation of thin coating of wall
material (polymer) around the
substance.”

3. Types -
Microencapsulation [
1 to 800
micrometers]
Microencapsulation [
800 to 1000
micrometers]

4. Theory of encapsulation-
1) Core material
2) Coating material

5. Core material (API)
Additives
Preservatives
Diluent
Disintegrents
Preservatives
Stabilizers

6. Coating material
1) Water soluble resins Ex. Gelatin, gum acacia, starch,
methyl cellulose
2) Water insoluble resins Ex. Ethyl cellulose, silicon
3) Waxes and lipids Ex. Paraben, bees wax, stearic
acid
4) Enteric resins Ex. Shellac, Cellulose acetate

7. Advantages-
It Masks the taste of bitter drugs to make them more palatable and
improving patient compliance.
Conversion of a liquid dosage form to pseudo solid or free-flowing
powder.
To provide environmental protection of the core material from moisture,
light, and oxygen.
To formulate sustained or prolonged release dosage forms that
continuously release the drugs at a constant rate for a set period.
To alter the physical and surface properties of certain drugs.

8. Disadvantages -
The cost of the materials used and the formulation process
might be higher than standard formulations.
Unstable release characteristics.
Incomplete or discontinued coating.
Inadequate stability and shelf life.

9. Methods of microencapsulation -.
• Physicomechanical methods
• Physicochemical methods
• Chemical methods

10. A] Physicochemical methods
1. Air suspension
2. Centrifugal extrusion
3. Pan coating
4. Spray drying – co-current
- counter current
- mix flow
5. Vibrational nosal method

11. B] Physicochemical
methods
1. Ionotropic gelatin
2. Coacervation
C] Chemical methods
1. Solvent evaporation
2. Polymerization - interfacial
- in situ
- matrix method

12. [A] Physicomechanical methods
1]Air suspension coating
• Developed by Prof. Dale E. Wurster.
Factors to be considered…..
1. Properties of drug material and coating material
2. Concentration of coating material
3. Coating material application rate
4. Amount of coating of coating material
5. Inset and outlet pressure operative maintenance

13. Air suspension

14. Process-

15. 2] Centrifugal extrusion
• Centrifugal extrusion is a liquid coextrusion process utilizing nozzles consisting. of a
concentric orifice located on the outer circumference of a rotating cylinder. i.e., the head.
• Centrifugal extrusionLiquids are encapsulated using a rotating extrusion head
containing concentric nozzles.
• This process is excellent for forming particles 400-2,000 µm in diameter
• Since the drops are formed by the breakup of a liquid jet, the process is only
suitable for liquid or slurry.
• A high production rate can be achieved, i.e., up to 22.5 kg of microcapsules can
be produced per nozzle per hour per head.
• Heads containing 16 nozzles are available.

16. 3] Pan coating
• Pan Coating process is used for solid particles greater
than 600 microns in size.
• The coating is applied as a solution, or as an atomized
spray, to the desired solid core material in the coating pan.

19. 4] Spray drying
Process….

20. Instruments of spray dryer
1. Air heater
2. Automizer (used to reduce molecularsize )
3. Main chamber
4. Cyclon
5. Blender / fan
6. Product collector

21. Co-current flow
• In a co-current flow spray dryer, the spray is directed into the hot
air entering the dryer and both pass through the chamber in the
same direction

22. Counter current
• In counter-current spray drying, the material to dry and the air
are injected at opposite location in the drying chamber

23. Mixed flow
• It combines both co-current
and counter current flow.

24. 5] Vibration nozzel method
• A fluid stream of liquid core and shell material is
pumped through concentric tubes and forms
droplets under the influence of vibration.
• Particle size 100-500 micrometer
• Capacity is 1 - 10,000 kg/ hr

25. [B] Physicochemical methods
1]Ionotropic gelation
• Ionotropic gelation (IG) is a technique that allows the production of nanoparticles and
microparticles by electrostatic interactions between two ionic species under certain
conditions. At least one of the species has to be a polymer.
• Example ..
Chemical reaction between sodium algenate or barium chloride with
verapamil, reduces the gastric irritation of Verapamil (antihypertensive)

26. 2] Co-acervation
• Coacervation can be defined as the separation of a
macromolecular solution into two immiscible liquid
phases: a dense coacervate phase and a dilute
equilibrium one.

27. Process-
(a)Core material dispersion in
solution of shell polymer;
(b) separation of coacervate from
solution;
(c) coating of core material by
microdroplets of coacervate;
(d)Coacervance of coacervate to
form continuous shell around
core particles.

28. [C] Chemical methods
1] Solvent evaporation
In the solvent evaporation method, the drug is dissolved,
dispersed, or emulsified into an organic polymer solution,
which is then emulsified into an external aqueous or oil
phase.
The microspheres are formed after solvent diffusion/evaporation
and polymer precipitation.

30. 2] Polymerization
i) Interfacial
ii) In-situ
iii) Matrix

31. i) Interfacial polymerization
• Interfacial polymerization is a
type of step-growth
polymerization in which
polymerization occurs at the
interface between two immiscible
phases (generally two liquids),
resulting in a polymer that is
constrained to the interface.

32. ii) In-situ polymerization
• In some
Polymerization
processes,
direct
Polymerization of
single monomer
is carried out on
the particle
surface.

33. iii) Matrix Polymerization
•A core material is imbedded in a
polymeric matrix during formation of
particles.