Microencapsulation
- 1. MICROENCAPSULATION TECHNIQUES Ravindra Kumar Gupta M.Pharm, DIPR Lecturer B.R. Nahata College of Pharmacy , Mandsaur (M.P.)
- 2. Microencapsulation is a process by which very tiny droplets or particles of liquid or solid material are surrounded or coated with a continuous film of polymeric material. The product obtained by this process is called as micro particles, microcapsules. Particles having diameter between 3 - 800µm are known as micro particles or microcapsules or microspheres. Particles larger than 1000µm are known as Macroparticles . INTRODUCTION
- 3. CLASSIFICATION OF MICROPARTICLE Generally Micro particles consist of two components a) Core material b) Coat or wall or shell material . 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 inert polymer.
- 4. ADVANTAGES : To Increase of bioavailability To alter the drug release To improve the patient’s compliance To produce a targeted drug delivery To reduce the reactivity of the core in relation to the outside environment To decrease evaporation rate of the core material. To convert liquid to solid form & To mask the core taste.
- 5. FUNDAMENTAL CONSIDERATION : Core material Coating material Vehicle Solid Liquid Microencapsulation Polymers Waxes Aqueous Nonaqueous Resins Proteins Polysaccharides
- 6. ROLE OF POLYMERS : Polymers are substances of high molecular weight made up by repeating monomer units. Polymer molecules may be linear or branched, and separate linear or branched chains may be joined by crosslinks. Polymers are used widely in pharmaceutical systems as adjuvants, coating materials and, a components of controlled and site- specific drug delivery systems
- 7. MICROENCAPSULATION TECHNIQUES: Air suspension techniques( Wurster) Coacervation process Spraydrying & congealing Pan coating Solvent evaporation Polymerization Extrusion Single & double emulsion techniques Supercritical fluid anti solvent method (SAS) Nozzle vibration technology
- 9. COACERVATION / PHASE SEPARATION 1.Formation of three immiscible phase 2.Deposition of coating 3.Rigidization of coating. Polymeric Membrane Droplets Homogeneous Polymer Solution Coacervate Droplets PHASE SEPARATION MEMBRANE FORMATION
- 11. SOLVENT EVAPORATIONS Step 1: Formation of a solution/dispersion of the drug into an organic polymer phase. Step 2: Emulsification of the polymer phase into an aqueous phase containing a suitable stabilizer, thus, forming a o/w emulsion. Step 3: Removal of the organic solvent from the dispersed phase by extraction or evaporation leading to polymer precipitation and formation of the microspheres. Polymer + Volatile organic solvent Organic Polymeric Phase Formation of Oil-in-Water Emulsion Solvent Evaporation Particle Formation by Polymer Precipitation RECOVERY OF POLYMERIC MICROPARTICLES Temperature increase Active Ingredient Addition into an aqueous phase (+o/w stabilizer)
- 12. SPRAY DRYING & CONGEALING ( COOLING) Spray drying : spray = aqueous solution / Hot air Spray congealing : spray = hot melt/cold air
- 13. Monodisperse microgels in the micron or submicron size range. Precipitation polymerization starts from a homogeneous monomer solution in which the synthesized polymer is insoluble. The particle size of the resulting microspheres depends on the polymerization conditions, including the monomer/co monomer composition, the amount of initiator and the total monomer concentration. POLYMERIZATION: Drug Addition of the alcoholic solution of the initiator (e.g., AIBN) 8 hrs Reaction time Monomer(s) (e.g. acrylamide, methacrylic acid) + Cross-linker (e.g. methylenebisacrylamide) Alcohol T (reaction) = 60 °C Nitrogen Atmosphere Preparation of the Polymerization Mixture Initiation of Polymerization Monodisoerse Latex Formation by Polymer Precipitation RECOVERY OF POLYMERIC MICROPARTICLES
- 14. EXTRUSION: This method was first patented in 1957. The advantage of extrusion is that it completely surrounds the core material with wall material. The process involves forcing a core material dispersed in a molten carbohydrate mass through a series of dies, into a bath of dehydrating liquid. When contact with the liquid is made, the carbohydrate case hardens to entrap the core material. The extruded filaments are separated from the liquid bath, dried using an anti-caking agent such as calcium tripolyphosphate and sized . This process is particularly useful for heat labile substances such as flavours, vitamin C and colours.
- 18. SAS METHOD :
- 19. APPLICATION OF MICROENCAPSULATION TECHNIQUES:
- 20. CONCLUSION: The microencapsulation technique offers a variety of opportunities such as protection and masking, reduced dissolution rate, facilitation of handling, and spatial targeting of the active ingredient. This approach facilitates accurate delivery of small quantities of potent drugs, reduced drug concentrations at sites other than the target organ or tissue and protection of labile compounds before and after administration and prior to appearance at the site of action. In future by combining various other approaches,microencapsulation technique will find the vital place in novel drug delivery system.