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Microencapsulation
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.
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Microencapsulation
- 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. Degradationcontrolled monolithic system 2. Diffusion controlled monolithic system 3. Diffusion controlled reservoir system 4. Erosion 5
- 6. List of coatingmaterial 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. 6
- 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 phaseseparation 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 Solidparticle 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 Dryingand 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 improvethe 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 15
- 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). 16
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