Microencapsulation
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This document provides an overview of microencapsulation including its classification, fundamental considerations, morphology, coating materials, reasons for use, release mechanisms, techniques, evaluation, applications, and disadvantages. Microencapsulation involves enclosing solids, liquids, or gases in microscopic particles with thin coatings to form microparticles, microcapsules, or microspheres ranging from 100-5000 microns. It allows for controlled release, masking of tastes, and protection of unstable or volatile materials. Common techniques include coacervation, pan coating, spray drying, solvent evaporation, and polymerization.
Microencapsulation
- 1. Bangabandhu Sheikh Mujibur Rahman Science & Technology University Department of Pharmacy A Presentation On Microencapsulation Presenting Group: Group C & Group E Course Title: Pharmaceutical Technology-II Corse Code: PHR361
- 2. Contents Microencapsulation Classification of Microcapsules Fundamental Consideration of Microencapsulation Morphology of the Microcapsules Coating material properties Reasons for microencapsulation Release Mechanism of Microencapsulation Techniques of Microencapsulation Evaluation of Microencapsulation Pharmaceutical Applications Advantages of Microencapsulation Disadvantages of Microencapsulation
- 3. Microencapsulation Microencapsulation is a process by which solids, liquids or even gases may be enclosed in microscopic particles by formation of thin coatings of wall material around the substances. The product obtained by this process is called as micro particles, microcapsules and microspheres. Coating size range may be 100 – 5000 Micron. Figure: Microcapsules
- 4. Red one’s are R.B.C Purple one’s are microspheres Microspheres
- 5. Microcapsules can be classified on three type. 1. Mono Nuclear: contain the shell around the core. 2. Poly Nuclear : Having many cores enclosed within shell. 3. Matrix : Distributed homogeneously into the shell material. Classification of Microcapsules Mono Nuclear Poly Nuclear Matrix
- 6. Fundamental Consideration of Microencapsulation
- 7. Morphology of the Microcapsules Micro capsules consist of two components - a) Core material b) Coat material Core Coat
- 8. Morphology of the Microcapsules Core Material: The material to be coated. It may be liquid or solid or gas. Liquid core may be dissolved or dispersed material.
- 9. Morphology of the Microcapsules Coat 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.
- 10. 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.
- 11. The drugs, which are sensitive to oxygen, moisture or light, can be stabilized by microencapsulation. For masking taste and odor of many drugs to improve patient compliance. Example-Ofloxacin. Obtain controlled and target release of the drug substance. For safe handling of the toxic materials. To avoid adverse effects like gastric irritation of the drug. Example- Indomethacin To increase of bioavailability. Incompatibility among the drugs can be prevented by microencapsulation. Example- Aspirin and Chlorpheniramine maleate Reduction of hygroscopicity. Example- NaCl To convert liquid active components into a pseudo solid system. Example- Eprazinone. Reduction of vaporization of volatile drugs. example- Methyl salicylate. Reasons for Microencapsulation
- 12. Release Mechanism of Microencapsulation The aim of a microencapsulation is the isolation of the core from its surrounding, the wall must be ruptured at the time of use. A variety of release mechanisms have been proposed for microcapsules. These are— 1. Degradation controlled monolithic system 2. Diffusion controlled monolithic system 3. Diffusion controlled reservoir system 4. Erosion
- 13. Release Mechanism of Microencapsulation 1.Degradation controlled monolithic system: Drug releases on degradation of matrix. Figure: Degradation controlled monolithic system
- 14. Release Mechanism of Microencapsulation 2.Diffusion controlled monolithic system: Drug released by diffusion then degradation of matrix occurs. Figure: Diffusion controlled monolithic system Diffusion
- 15. Release Mechanism of Microencapsulation 3.Diffusion controlled reservoir system: Drug from capsule diffuses then rate controlling membrane erodes. Diffusion Fig: Diffusion controlled reservoir system Controlled release
- 16. Release Mechanism of Microencapsulation 4.Erosion: Due to pH & enzymatic hydrolysis. Fig: Erosion
- 17. Techniques of Microencapsulation 1. Air suspension techniques( Wurster) 2. Coacervation process 3. Pan coating 4. Spray drying & congealing 5. Solvent evaporation 6. Polymerization There are some techniques for microencapsulation---
- 18. Air Suspension Techniques (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. Wurster Apparatus
- 20. Coacervation Coacervation may be defined as a process when solution of two hydrophilic colloids are mixed under suitable conditions where separation of liquid phase takes place. There are two methods for coacervation are available, namely simple and complex processes.
- 21. Coacervation 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.
- 22. Pan Coating
- 23. Spray Drying & Congealing
- 24. Solvent Evaporation In the case in which the core material is dispersed in the polymer solution, polymer shrinks around the core. In the case in which core material is dissolved in the coating polymer solution, a matrix - type microcapsule is formed. The core materials may be either--- 1. water - soluble or 2. water - insoluble materials.
- 27. A relatively new microencapsulation method utilizes polymerization techniques to from protective microcapsule coatings in situ. 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. Polymerization
- 30. Physicochemical Evaluation Characterization: The characterization of the micro particulate carrier is important, which helps to design a suitable carrier for the proteins, drugs or antigen delivery. This microspheres have different microstructures. These microstructures determine the release and the stability of the carrier.
- 39. Pharmaceutical Applications To improve the flow properties. e.g. Thiamine, Riboflavin 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 unpleasant taste and odor. e.g. Aminophylline, castor oil To convert liquids into solids. e.g. Castor oil, Eprazinone, To reduce gastric irritation. e.g. Nitrofurantoin, Indomethacin
- 41. Disadvantages of Microencapsulation Disadvantages of Microencapsulation
- 42. Thank You