MICROENCAPSULATION
By SANA TABASSUM (B.Pharm)
Under the guidance ofMrs.Ch.S VIJAYA VANI,M.Pharm.
Associate Professor,Department of Pharmaceutics.
A Presentation
On
CMR COLLEGE OF PHARMACY
DEFINITIONMicroencapsulation is the process by which tiny solid particles or droplets of liquid are surrounded or coated with a continuous film of polymeric material to produce capsules in the micrometer to millimeter range. The product obtained by this process is called as microcapsules.1 Microcapsule
MICROCAPSULES
Microcapsules in blood stream
Microscopic view of microcapsules
Advantages of microencapsulationMasking of bitter taste drugs. Eg: Ofloxacin.Conversion of liquid to pseudo solid. Eg: Eprazinone.2
Environmental protection.Eg: Vit.A.Palmitate. Reduction of hygroscopicity .Eg: NaCl. Reduction of vaporization of volatile drugs. Eg: Methyl salicylate.Prevention of incompatibilities among drugs. Eg: Aspirin and Chlorpheniramine maleate .2
Disadvantages of Microencapsulation.
Possible cross reaction between core and shell material.Difficult to achieve continuous and uniform film.Shelf life of hygroscopic drugs is reduced.More production costs.More skill and knowledge is required.2
MECHANISMS OF DRUG RELEASE
Degradation controlled monolithic system
Diffusion controlled monolithic system
Diffusion controlled reservoir system
Erosion
MECHANISMS OF DRUG RELEASE1)Degradation controlled monolithic
system-Drug releases on degradation of matrix.
2)Diffusion controlled monolithic system-Drug released by diffusion then degradation of matrix occurs.
3)Diffusion controlled reservoir system-Drug from capsule diffuses then rate controlling membrane erodes.
4)Erosion-Due to pH and enzymatic hydrolysis.2
CLASSIFICATION OF MICROCAPSULES2
Mononuclear Polynuclear Matrix Mononuclear with multiple shells
MATERIALS INVOLVED IN FORMULATION
A)Core Material:Specific material to be coated.It may be liquid or solid. Liquid core may be dissolved or dispersed material.3
Core Material Purpose Final Product Form
Acetaminophen Taste masking Tablet
Potassium chloride
Reduces gastric irritation
Capsule
Isosorbide dinitrate
Sustained release
Capsule
Examples of core material
B)Coating Material: Inert substance which coats on core with desired thickness.
Composition of coating solution•Inert polymer.•Plasticizer- Triethylcitrate, glycerin•Solvents- Water,cyclohexane.•Co solvents-Glycerol, sorbitol.
Examples of various coating material 3
Category of Coating Material
Examples
Water soluble resins Gelatin, Polyvinylpyrrolidone(PVP).
Water insoluble resins Ethyl cellulose, Polyethylene.Waxes and lipids Paraffin, Carnauba, Beeswax.Enteric resins Shellac, Zein.
TECHNIQUES TO MANUFACTURE MICROCAPSULES
S.No Physical Methods Chemical Methods
A) Air Suspension Solvent EvaporationB) Pan Coating PolymerizationC) Coarcervation Phase
Separation Interfacial
Polymerization In-situ PolymerizationD) Multi-orifice
Centrifugal ProcessE) Spray Drying & Spray
CongealingF) Fluidized Bed
Technology
A)Air Suspension(Wurster Method)Within the coating chamber, particles are suspended on an upward moving air stream.
Spraying of coating material on the air suspended particles.
The cyclic process is repeated depending upon purpose of microencapsulation.
Air stream serves to dry the product.3
Advantages: Disadvantages:Various coating material can be used.
Applicable only to solid core material.
Capacity is more
Agglomeration of the particles
WURSTER APPARATUS
B) Pan Coating
The particles are tumbled in a pan while the coating material is applied slowly as solution or atomized spray to the core.
To remove the coating solvent, warm air is passed over the coated materials or dusting of talc is done.
Medicaments are usually coated onto nonpareil sugar seeds and then coated with polymers.3
Advantages: Disadvantages:Suitable to larger particles.
Time consuming.
Sustained release preparations.
High material loss.
C) Coacervation Phase Separation:
Simple coacervation Complex coacervationA desolvation agent is added for phase separation
It involves complexation between two oppositely charged polymers.
Steps involved in this process are:-1) Formation of three immiscible phases.2) Deposition of liquid coating material upon
the core material.3) Rigidization of coating.
Coacervation process
Various methods to obtain three immiscible phases:
1) Temperature change2) Incompatible Polymer Addition3) Non-Solvent Addition4) Salt Addition5) Polymer-Polymer Interaction(Complex Coacervation)
Temperature change:
Temperature-composition phase
diagram for a binary system of a polymer
and a solvent.
TEM
PERA
TURE
POLYMER CONCENTRATION %
XA
BC D
E
F G
•Point X represents –single phase.
The phase-boundary curve indicates that with decreasing temperature.
One phase becomes polymer rich.
Other phase becomes polymer poor.
Eg: N-acetyl p-amino phenol.4
Non-Solvent Addition:
A liquid that is a non-solvent for a given polymer can be added to a solution of the polymer to induce phase separation.
Eg: Addition of isopropyl ether to CAB dissolved in methyl ethyl ketone.Core: Methyl scopolamine HBr.4
XA
BC
D E
SOLVENT 100%
100%POLYMER
100%NON SOLVENT
Phase diagram for phase-separation/
coacervation induced by Non Solvent
Addition
Salt Addition
Soluble inorganic salts can be added to aqueous solutions of water-soluble polymers .Eg: Sodium sulfate,Core-Vitamin in corn oil.4
Polymer-Polymer Interaction (Complex Coacervation):Steps involved:4
1. Formation of an O/W emulsion
2. Formation of the coating
3. Stabilization of the coating
A
CB
WATER100%
100%P -
100%P+
Ternary Phase diagram
X
D) Multi-orifice Centrifugal Process
Advantages:Encapsulates both solid and liquid materials.Production rate is more.
It utilizes centrifugal forces to hurl a core material particle through an enveloping microencapsulation membrane .4
E) Spray Drying and Spray Congealing:
Spray Drying Spray CongealingCoating solidification effected by rapid evaporation of solvent in which coating material is dissolved.
Coating solidification is effected by thermally congealing a molten coating material.4
Advantages:Low bulk density product.Porous nature capsules.Free flowing particles.
F) Solvent Evaporation
Advantages:Encapsulation of hydrophobic and hydrophilic drug.Simple technique.Encapsulation of solid and liquid drug.
G) Polymerization
Interfacial Polymerization In-situ Polymerization
NOVEL METHODSA) Vibration Technology
A fluid stream of liquid core and shell materials is pumped through concentric tubes and forms droplets under the influence of vibration. 1
B) Jet Cutter TechnologyA solid jet of fluid coming out of a nozzle by means of rotating cutting wires is cut into cylindrical segments which then form beads due to surface tension on their way to a hardening device.1
C) Rapid Expansion Of Super Critical Solution(RSS)Core and the shell material are maintained at high pressure and then released at atmospheric pressure through a small nozzle.
Sudden drop in pressure causes desolvation of the shell material.1
APPLICATIONSTo reduce gastric and other GIT irritations. Eg: Aspirin preparations.Prolonged release dosage forms preparation. Preparation of enteric-coated dosage forms .Replacement of therapeutic agents (not taken orally like insulin), gene therapy and in use of vaccines for treating AIDS, tumors, cancer and diabetes.Delivery of DNA vaccines.Prodrug approach. Eg: Minocycline HCl.Biodegradable and biocompatible microparicles preparations.Example: Risperidone or testosterone.5
Marketed formulations prepared using microcapsules5
S.No Brand Name
Generic Name
Categoryof drug
1. Lupin Cefadroxil Antibiotic
2. ZORprin CR Aspirin Anti-arthritic
3. Glipizide SR Glucotrol Anti diabetic
REFERENCES1. http://www.authorstream.com/Presentation/vivekchauhan-
1147305-microencapsulation.2. Hammad umer et.al,” International Journal of Research in
Pharmaceutical and Biomedical Sciences” ISSN: 2229-3701.
3. S. S. Bansode et.al,” Institute of Pharmaceutical Education And Research”, Volume 1, Issue 2, March –April 2010; Article 008 .
4. Lachman LA, Liberman HA, Kanig JL. The Theory and Practice of Industrial Pharmacy. Mumbai, India: Varghese Publishing House; 3:414-415.
5. http://www.authorstream.com/Presentation/thokesagar-1295371-shree/
THANK
YOU
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