MICROENCAPSULATION Formulation, Method of Preparation TJS.ppt
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Microencapsulation for Industrial Pharmacy, Pharmaceutical Technology
MICROENCAPSULATION Formulation, Method of Preparation TJS.ppt
- 1. MICROENCAPSULATION Dr. T. J. Shaikh A.R.A. COLLEGE OF PHARMACY, Nagaon, DHULE
- 2. DEFNITION Microencapsulation is a means of applying relatively thin coatings of polymer to small particle of solids or liquids and dispersions. Microencapsulation differ from macrocoating technique in that the former involves coatings of particles ranging from several tenths of a micron to 5000 micron in size
- 3. Microencapsulation provides the mean of : • Converting liquid to solids • Altering colloidal and surface properties • Providing environmental protection • Controlling the release characteristics or availability of coated materials. Uniqueness of microencapsulation is the smallness of the coated particles and their subsequent use in variety of dosage forms.
- 4. Morphology of Microcapsules: • The morphology of microcapsules depends mainly on the core material and the deposition process of the shell. 1- Mononuclear (core-shell) microcapsules contain the shell around the core. 2- Polynuclear capsules have many cores enclosed within the shell. 3- Matrix encapsulation in which the core material is distributed homogeneously into the shell material. In addition to these three basic morphologies, microcapsules can also be mononuclear with multiple shells, or they may form clusters of microcapsules.
- 5. • Morphology of Microcapsules
- 6. Formulation Microspheres consist of two parts 1 Core material 2 Coating material Core material:- • It is defined as the specific material to be coated, can be liquid or solid in nature . • The composition of core material can be varied • This ability provide definite flexibility and utilization of this character allows effectual design and development of desired microcapsule properties.
- 7. Coating materials properties: • Stabilization of core material. • Inert toward active ingredients. • Controlled release under specific conditions. • Film-forming, pliable, tasteless, stable. • Non-hygroscopic, no high viscosity, economical. • Soluble in an aqueous media or solvent or melting. • The coating can be flexible, brittle, hard, thin etc.
- 8. Classification of Coating material Water soluble resin Gelatin Gum Arabica PVP CMC MC Hydroxy ethyl - cellulose Water Insoluble resin Ethyl cellulose Polyethylene Polyamide / nylon Polymethacrylate Cellulose nitrate - silicones Waxes and Lipids Paraffin Beewax Stearic acid Stearyl alcohol Glyceryl stearates Enteric resin Shellac Cellulose acetate- phthalate Zein
- 10. Microencapsulation Techniques 1) Air suspension 2) Coascervation /Phase separation 3)Multiorifice centrifugation 4)Pan coating 5) Spray coating 6) Solvent evaporation 7) Interfacial polymerization
- 11. •Air suspension It is known as Wurster process which consist of the dispersing of solid, particulate core material in a supporting air stream and the spray coating of the air suspended particles within a coating chamber, particles are suspended on an upward moving air stream.
- 12. Fluidized-Bed Technology: - Different types of fluid-bed coaters include top spray, bottom spray, and tangential spray. - used for encapsulating solid or liquids absorbed into porous particles. Steps: 1-Solid particles to be encapsulated are suspended on a jet of air and then covered by a spray of liquid coating material. 2- The rapid evaporation of the solvent helps in the formation of an outer layer on the particles. 3- This process is continued until the desired thickness and weight is obtained.
- 13. Schematics of a Fluid-bed coater. (a) Top spray; (b) Bottom spray; (c) Tangential spray
- 14. Coacervation –Phase separation Coacervation occurs in three stages 1)Formation of three immiscible chemical phase 2)Application of coating material 3) Rigidization of coating material 1)Formation of three immiscible chemical phase Three immiscible phases are 1) Coating material 2) Core material 3) Liquid manufacturing vehicle
- 16. • Core material is dispersed in a solution of coating polymer • The solvent for polymer being the liquid manufacturing vehicle phase • Separation of coating material from manufacturing vehicle take place by one of the methods below:- a)Temperature changes E F G Temp polymer
- 17. • It is a biphasic system –polymer and solvent phase diagram • Above FEG polymer solution exists as homogeneous phase when temperature decreases it crosses phase boundary and polymer get separated from vehicle phase . Polymer coaservates around core particle and microencapsulation occurs Eg. Microencapsulation of acetaminophen using ethyl cellulose in cyclohexane solution
- 18. b)By adding Incompatible polymer It involve a ternary system consisting of solvent and two polymer x and y. Polymer x is dissolved in vehicle core particle is dispersed in polymer x. To this incompactible polymer y is added. When concentration of polymer y increases it crosses the phase boundary and phase separation occur. Polymer coacervates around core material resulting in microencapsulation. E 100% polymerY 100% polymerX
- 19. Eg. microencapsulation of methylene blue hydrocolloid using ethyl cellulose in toluene solution Incompatible polymer- polybutadiene c) By adding Non-solvent to polymer A non solvent is added instead of incompatible polymer Eg: microencapsulation of methyl scopolamine using cellulose acetate butyrate Solvent-Methyl ethyl ketone Nonsolvent-Isopropyl ether
- 20. d) By Adding salt Soluble inorganic salt is added to aqueous solution of certain water soluble polymers to cause phase separation Eg: oil soluble vitamin microencapsulation induced by adding sodium sulphate to a gelatin solution Inorganic salt –Sodium sulphate
- 21. e)Polymer-Polymer Interaction The interaction of oppositely charged polyelectrolyte can result in the formation of a complex having such reduced solubility that phase separation occurs eg: polymer used are acacia (+ve) and gelatin (-ve)
- 22. 2)Application of Coating material In this adsorption of coating material at the interface between core material and vehicle phase. It can be enhanced by increasing total interfacial energy of the system 3)Rigidisation of Coating material The prepared microcapsules are stabilized by crosslinking (with formaldehyde), desolvation or thermal treatment.
- 23. Multiorifice Centrifugation 1- Suspensions of core particles in liquid shell material are poured into rotating disc. 2- Due to the spinning action of the disc, the core particles become coated with the shell material. 3- The coated particles are then cast from the edge of the disc by centrifugal force. 4- After that the shell material is solidified by external means (usuall cooling). This technology is rapid, cost-effective, relatively simple and has high production efficiencies.
- 24. Pan Coating: • Solid particles are mixed with a dry coating material. • The temperature is raised so that the coating material melts and encloses the core particles, and then is solidified by cooling. • Or, the coating material can be gradually applied to core particles tumbling in a vessel rather than being wholly mixed with the core particles from the start of encapsulation.
- 26. Spray-Drying & Spray-congealing : Microencapsulation by spray-drying is a low-cost commercial process which is mostly used for the encapsulation of frgrances, oils and flavors. Steps: 1- Core particles are dispersed in a polymer solution and sprayed into a hot air stream. 2- The shell material solidifies onto the core particles as the solvent evaporates. - The microcapsules obtained are of polynuclear or matrix type.
- 28. Spray Drying
- 29. Spray-congealing: This technique can be accomplished with spray drying equipment when the protective coating is applied as a melt. 1- The core material is dispersed in a coating material melt. 2- Coating solidification (and microencapsulation) is accomplished by spraying the hot mixture into a cool air stream. e.g. microencapsulation of vitamins with digestible waxes for taste masking.
- 30. Solvent Evaporation - It is the most extensively used method of microencapsulation. 1-Prepare an aqueous solution of the drug (may contain a viscosity building or stabilizing agent) 2- Then added to an organic phase consisting of the polymer solution in solvents like dichloromethane or chloroform with vigorous stirring to form the primary water in oil emulsion. 3- This emulsion is then added to a large volume of water containing an emulsifier like PVA or PVP to form the multiple emulsion(w/o/w). 4- The double emulsion is then subjected to stirring until most of the organic solvent evaporates, leaving solid microspheres. 5- The microspheres can then be washed and dried.
- 32. Polymerization: This methods involve the reaction of monomeric unit located at the interface existing between a core material substance and a continuous phase in which the core material is dispensed. The continuous or core material supporting phase is usually a liquid or gas and therefore the polymerization reaction occur at a liquid– liquid, liquid-gas, solid-gas interface.
- 33. Dru g Preparation of Polymerization mixture Initiation of polymerization Monodisoerse latex formation by polymer precipitation Recovery of polymeric micro particle Monomer (S)(eg; acrylamide, methacrylic acid ) +Cross linker (eg;methylene bis acrylamide ) Drug Alcohol Addition of alcoholic solution of the initiation(eg;AIBN 8 Hrs Reaction time T(reaction)=60c.Nitrogen atmosphere
- 34. Application • Sustained release or prolonged action medications • Taste marked chewable tablets ,powders and suspension • Single layer tablet containing chemically incompatible ingredients • New formulation for creams, ointment, aerosols • Pharmaceutically related areas such as hygiene ,diagnostic aid , and medical equipment design also amendable to microencapsulation application. • Decrease the gastric irritation eg;KCl
- 35. Benefits of Microencapsulation: 1- Microorganism and enzyme immobilization. - Enzymes have been encapsulated in cheeses to accelerate ripening and flavor development. The encapsulated enzymes are protected from low pH and high ionic strength in the cheese. • The encapsulation of microorganisms has been used to improve stability of starter cultures.
- 36. 2-Protection against UV, heat, oxidation, acids, bases (e.g.colorants and vitamins). e.g. Vitamin A / monosodium glutamate appearance (white) protection (water, T, light) 3- Improved shelf life due to preventing degradative reactions (dehydration, oxidation). 4-Masking of taste or odours. 5- Improved processing, texture and less wastage of ingredients. - Control of hygroscopy - enhance flowability and dispersibility - dust free powder - enhance solubility
- 37. 6-Handling liquids as solids 7-There is a growing demand for nutritious foods for children which provides them with much needed vitamins and minerals during the growing age. Microencapsulation could deliver the much needed ingredients in children friendly and tasty way. 8- Enhance visual aspect and marketing concept.
- 38. • 9- Carbonless copy paper was the first marketable product to employ microcapsules. A coating of microencapsulated colorless ink is applied to the top sheet of paper, and a developer is applied to the subsequent sheet. When pressure is applied by writing, the capsules break and the ink reacts with the developer to produce the dark color of the copy. 10-Pesticides:- are encapsulated to be released over time, allowing farmers to apply the pesticides less amounts than requiring very highly concentrated and toxic initial applications followed by repeated applications to combat the loss of efficacy due to leaching, evaporation, and degradation.
- 39. 10-Today's textile industry makes use of microencapsulated materials to enhance the properties of finished goods. One application increasingly utilized is the incorporation of microencapsulated phase change materials (PCMs). Phase change materials absorb and release heat in response to changes in environmental temperatures. When temperatures rise, the phase change material melts, absorbing excess heat, and feels cool. Conversely, as temperatures fall, the PCM releases heat as it solidifies, and feels warm. This property of microencapsulated phase change materials increase the comfort level for users of sports equipment, clothing, building materials, etc.
- 40. 12- Ingredients in foods are encapsulated for several reasons. Most flavorings are volatile; therefore encapsulation of these components extends the shelf-life of these products. • Some ingredients are encapsulated to mask taste, such as nutrients added to fortify a product without compromising the product’s intended taste Alternatively, flavors are sometimes encapsulated to last longer, as in chewing gum.
- 41. 13- Controlled and targeted release of active ingredients. 14- Microencapsulation allows mixing of incompatible compounds