Need of Microencapsulation
DEFINITION: A process by which solid , droplets of liquid and
dispersion can be enclosed in microscopic particle by the formation
of thin coating of wall material around the substance.
Core material Wall material
NEED OF MICROENCAPSULATION:
Entrapment of a material inside microparticles for
To Increase of bioavailability.
To alter the drug release.
To produce a targeted drug delivery.
To protect the core from outside environment.
To decrease evaporation rate of the volatile core material.
To convert liquid into solid form.
To mask the core taste.
Protects the GIT from irritant effects of the drug.
Core material Coating material Vehicle
Aqueous No aqueous
The material to be coated.
It may be liquid or solid in nature.
Liquid core may be dissolved or dispersed material.
COMPOSITION OF CORE MATERIAL:
Drug or active constituent
Additive like diluents
Capable of forming a film cohesive with core material.
It should be compatible with the core material.
It Should be stable, non reactive.
Provide desired coating properties like strength, flexibility&
COMPOSITION OF COATING:
1. MICROENCAPSULATION TECHNIQUES:
1. Air suspension technique (Wurster)
2. Coacervation-Phase separation process
3. Spray drying & spray congealing
4. Multiorifice Centrifugation Process
5. Pan coating
6. Solvent evaporation
8. Nozzle vibration technology
9. Jet cutter technology
11. Single & double emulsion techniques
12. Supercritical fluid anti solvent method (SAS)
MICROENCAPSULATION PROCESSES &
1.Formation of three immiscible phases
2.Deposition of coating
3.Rigidization of coating
Used for large size particles i.e. 600-5000 μm size.
Coating pan is used for this operation.
Coating solution is applied as a solution or atomized
spray on sugar pellets (Non-pareil sugar seeds).
Warm air is passed to remove the coating solvent.
+ Volatile organic solvent
Organic Polymeric Phase
Formation of Oil-in-Water
Particle Formation by Polymer
RECOVERY OF POLYMERIC
Addition into an aqueous
phase (+o/w stabilizer)
6.SPRAY DRYING & CONGEALING :
Spray drying : spray = aqueous solution / Hot air
Spray congealing : spray = hot melt/cold air
Method developed by Chang
Aliphatic diamine Dicarboxilic acid halide
Liq- Liq. interface
(D) Vibration technology
•This technology is based on an ancient principle (Lord
Rayleigh, in the late 19th century) which shown that a
laminar liquid jet breaks up into equally sized droplets by
a superimposed vibration. The parameters are the
frequency, the velocity of the jet and the nozzle diameter.
•To guarantee the production of uniform beads or
capsules and to avoid large size distributions due to
coalescence effects during the flight, the droplets pass
through an electrostatic field to be charged. As a result
these droplets don’t hit each other during the flight and
will be spread over a larger surface of the gelation bath
thus resulting in monodisperse beads.
(E) JetCutter technology
The JetCutter is a simple technology for bead production that meets
the requirement of producing monodisperse beads originating from
low up to high viscous fluids with a high throughput `
ADVANTAGE OF MICROENCAPSULATION
• administered dose of a
drug is subdivided into
small units that are
spread over a large area
of the gastrointestinal
tracts, which may
enhance absorption by
diminishing local drug
• Micro-K ExtenCaps
Its costly process, not economical.
More skill is required.
It is difficult to get continuous & uniform film.
1.Microcapsules: The active agent forms a core surrounded by an
inert diffusion barrier.
2.Microspheres: The active agent is dispersed or dissolved in an
Size of microcapsules- Sieving Method
Amount of drug present In microcapsules
Dissolution test- Invitro drug release
Leon, L., Herbert A. L., Joseph, L. K; “ The Theory And
Practice Of Industrial Pharmacy”, 3rd edition (1990),
Varghese Publishing House, Page no. 412-428.
Vyas S.P, Khar R.K; “Targeted & Controlled drug
delivery ’’ Novel carrier systems,1st
publisher & distributors New delhi, page no.418-455.
Wise D.L, “Handbook of pharmaceutical controlled
edition , Marcel Dekker New York,
page no. 271-286,