![Particle size analysis
For size distribution analysis, different sizes in a
batch were separated by sieving by using a set of
standard sieves. The amounts retained on
different sieves were weighed [5]
.
Encapsulation efficiency [8]
Encapsulation efficiency was calculated using
the formula
:
Encapsulation efficiency = Actual Drug Content /
Theoretical Drug Content ×100](https://image.slidesharecdn.com/4-microencapsulation-250204165513-b63d3d8f/85/4-microencapsulation-ppt11111111111111-28-320.jpg)
4- microencapsulation .ppt11111111111111
- 2. Microencapsulation Microencapsulation is a means of applying thin uniform coatings to microparticles of solids dispersion or droplets of liquids.
- 3. Microcapsules are small particles that contain an active Microcapsules are small particles that contain an active agent ( agent (core material core material) surrounded by a shell or ) surrounded by a shell or coating coating. . Their diameters generally range from a few microns to a Their diameters generally range from a few microns to a few millimetres. few millimetres. Microcapsules can have many different types and Microcapsules can have many different types and structures: structures: a) simple droplets of liquid core material surrounded by a a) simple droplets of liquid core material surrounded by a spherical shell ( spherical shell (Microcapsules) Microcapsules) b) irregularly-shaped particles containing small particles of b) irregularly-shaped particles containing small particles of solid core material dispersed in a continuous polymer shell solid core material dispersed in a continuous polymer shell matrix matrix )microspheres microspheres) ) Microcapsules
- 4. Mechanisms for the release of encapsulated core materials: Disruption of the coating by pressure, shear, or abrasion forces. Enzymatic degradation of the coating where permeability changes. Diffusion or leaching of core materials. The rate of release of core material is a function of : • the permeability of the coating to core material. • the dissolution rate of the core materials • the coating thickness • the concentration gradient existing across the coating membrane.
- 5. application of microencapsulation Four important areas of microencapsulation application are : 1. The stabilization of core materials 2. The control of release or availability of core materials 3. Separation of chemically reactive ingredients within a tablet or powder mixture. 4. Taste-masking.
- 6. Microencapsules can be formulated as powders and suspensions, single-layer tablets, chewable tablets, creams, ointments, aerosols, dressings, plasters, suppositories, and injectables.
- 7. Core Material The core material is the material to be coated, which may be The core material is the material to be coated, which may be liquid liquid or or solid solid in nature. in nature. The composition of the core material can be varied: The composition of the core material can be varied: The liquid core can include dispersed and/or dissolved material. The liquid core can include dispersed and/or dissolved material. The solid core can be a mixture of active constituents, stabilizers, The solid core can be a mixture of active constituents, stabilizers, diluents, excipients , and release-rate retardants or accelerators. diluents, excipients , and release-rate retardants or accelerators.
- 8. The coating material should: • Be capable of forming a film • Be chemically compatible and non-reactive • Provide the desired coating properties - carboxy methyl cellulose - ethyl cellulose - cellulose acetate phthalate - poly vinyl alcohol - gelatin, gelatin- gum arabic - poly hydroxy cellulose - waxes - chitosan Coating Materials
- 9. Microencapsulation methods 1. Air suspension 2. Coacervation-phase separation 3. Spray drying 4. Congealing 5. Pan coating 6. Solvent evaporation techniques
- 10. Microencapsulation Processes and Their Applicabilities Microencapsulation Microencapsulation Process Process Applicable Core Applicable Core Material Material Approximate Approximate Particle Size (µm) Particle Size (µm) Air suspension Air suspension Solids Solids 35-5000 35-5000 Pan coating Pan coating Solids Solids 600-5000 600-5000 Multiorifice Multiorifice centrifugal centrifugal Solids & liquids Solids & liquids 1-5000 1-5000 Coacervation-phase Coacervation-phase separation separation Solids & liquids Solids & liquids 2-5000 2-5000 Solvent evaporation Solvent evaporation Solids & liquids Solids & liquids 5-5000 5-5000 Spray drying and Spray drying and congealing congealing Solids & liquids Solids & liquids 600 600
- 11. A, control panel; B, coating chamber; C, particles being treated; D, process airflow; E, air distribution plate; F, nozzle for applying film coatings. Microencapsulation by air suspension techniques using Wurster Air Suspension Apparatus Air Suspension Schematic drawings of Wurster Air Suspension Apparatus
- 13. Coacervation-Phase Separation Step 1. formation of three immiscible chemical phases (vehicle ,Core and liquid coating). Coating formation during coacervation phase-separation process consists of three steps carried out under continuous agitation: Step 2. Deposition of liquid coating material. Step 3. Rigidization of the coating
- 14. Step 1 Formation of three immiscible chemical phases: A liquid manufacturing vehicle phase, a core material phase, and a coating material phase. To form the three phases The coating material phase, an immiscible polymer in a liquid state, is formed by utilizing one of the methods of phase separation coacervation
- 15. Step 2 Depositing the liquid polymer coating upon the core material. This is accomplished by controlled, physical mixing Deposition of the liquid polymer coating around the core material The continued deposition of the coating material is promoted by a reduction in the total free interfacial energy of the system
- 16. Step 3 Rigidizing the coating By thermal , cross-linking (formaldehyde), or desolvation techniques
- 17. Temperature Change Temperature-composition phase diagram for a binary system of a polymer and a solvent. TEMPERATURE POLYMER CONCENTRATION % X A B C D E F G Water insoluble polymer : Ethylcellulose Solvent : cyclohexane Core material: N acetyl p- amino phenol
- 18. Incompatible Polymer Addition Core materail: Methylene blue hydrochloride Coating material: Ethyl cellulose Solvent : Toulene Incompatible polymer: Liquid polybutadiene Rigidization with hexane X A B C D E SOLVENT SOLVENT 100% 100% 100% 100% POLYMER Y POLYMER Y 100% 100% POLYMER x POLYMER x Phase diagram for phase- Phase diagram for phase- separation/ coacervation separation/ coacervation induced by Incompatible induced by Incompatible Polymer Addition Polymer Addition
- 19. Nonsolvent Addition Core material: Methylscopolamine Coating material: Cellulose acetate butyrate Solvent: Methyl ethyl ketone Non solvent : Isopropyl ethet X A B C D E SOLVENT SOLVENT 100% 100% 100% 100% POLYMER POLYMER 100% 100% NON SOLVENT NON SOLVENT Phase diagram for phase- Phase diagram for phase- separation/ coacervation separation/ coacervation induced by Non Solvent induced by Non Solvent Addition Addition
- 20. Salt Addition Core material: Oil soluble vitamins Corn oil, gelatin and water 20% of sodium sulphate X A B C D E WATER WATER 100% 100% 100% 100% POLYMER POLYMER 100% 100% SALTS SALTS Phase diagram for phase- Phase diagram for phase- separation/ coacervation separation/ coacervation induced by Salt Addition induced by Salt Addition
- 21. Polymer-Polymer Interaction (Complex Coacervation) The interaction of oppositely charged polyelectrolytes can result in the formation of a complex having reduced solubility and phase separation occurs. Complex coacervation process consists of three steps : 1. Formation of an O/W emulsion 2. Formation of the coating 3. Stabilization of the coating The phase diagram for a ternary system comprised of two dissimilarly charged polyelectrolytes in water (as solvent). A C B WATER WATER 100% 100% 100% 100% P P - - 100% 100% P+ P+ Phase diagram for phase- Phase diagram for phase- separation/ coacervation separation/ coacervation induced by Polymer induced by Polymer Interaction Interaction X
- 22. Gelatin and gum arabic are typical polyelectrolytes that can interact. Gelatin, at pH below its isoelectric point, possesses a positive charge, whereas the acidic gum arabic is negatively charged. Under the proper temperature, pH, and concentrations, the two polymers can interact through their opposite electrical charges, forming a complex that exhibits phase separation/coacervation.
- 23. Solvent evaporation This method of microencapsulation is the most widely used due to: 1.Simple technique . 2.this method allow encapsulation of hydrophobic and hydrophilic drug 3.this method allow encapsulation of solid and liquide drug 4.Microcapsule produced have wide size rang (5-5000µm)
- 25. Pan Coating
- 26. Spray Drying and Spray Congealing
- 27. Percentage Yield Percentage yield = Amount of microcapsule obtained / Theoretical Amount×100 Scanning electron microscopy . The SEM photomicrographs was taken at the acceleration voltage of 20 KV . EVALUATION OF MICROCAPSULES
- 28. Particle size analysis For size distribution analysis, different sizes in a batch were separated by sieving by using a set of standard sieves. The amounts retained on different sieves were weighed [5] . Encapsulation efficiency [8] Encapsulation efficiency was calculated using the formula : Encapsulation efficiency = Actual Drug Content / Theoretical Drug Content ×100
- 29. Drug release was studied by using USP type II dissolution test apparatus (Electrolab TDT 08L) in Phosphate buffer of pH 7.4 (900 ml). The paddle speed at 100 rpm and bath temperature at 37 ± 0.5°c were maintained through out the experiment . A sample of microcapsules equivalent to 100 mg of cefotaxime sodium was used in each test. Aliquot equal to 5ml of dissolution medium was withdrawn at specific time interval and replaced with fresh medium to maintain sink condition. Sample was filtered through Whatman No. 1 filter paper and after suitable dilution with medium; the absorbance was determined by UV spectrophotometer (Elico SL159) at 254 nm . All studies were conducted in triplicate (n=3). The release of drug from marketed sustained release tablet was also studied to compare with release from microcapsules . Invitro Drug release Studies