Microencapsulation

This presentation includes information related to the different technologies used for preparation of micro-capsules and also their evaluation parameters.

1. Microencapsulation Presented By: Poonam Y. Purkar M.Pharm E.mail : [email protected] Sir. Dr. M.S.Gosavi College of Pharmaceutical Education & Research. Nasik.

2. Content: Introduction Concept of Microencapsulation Merits of Microencapsulation Demerits of encapsulation Methods of preparation Chemical encapsulation process Mechanical encapsulation process Evaluation of Microcapsules Applications of Microcapsules

3. Introductions: A small entities that contain active agent or core material surrounded by shell or embedded into matrix structure. Commercial microparticles have a diameter 3 to 800 µm and contains 10-90% w/w core.

4. Microcapsules: droplet of liquid surrounded by spherical shell Microspheres: small particles of solid material dispersed in a continuous polymer shell matrix

5. Concept of Microencapsulation: Materials involved in microencapsulation: Core material: specific material to be coated It may be a liquid or solid Examples: for masking the taste of acetaminophen, aspirin, microcapsules can be prepared. Coating material: stabilization, reduced volatility, release characteristics, environmental conditions should be taken in to consideration while selecting polymer as coating material. Examples: gelatin, PVP, EC, paraffin, beeswax

6. Morphology of microcapsules: Polynuclear

7. Mechanism & Kinetics of Drug release: Disruption of coating by pressure, shear or abrasion forces Enzymatic degradation of the coating where permeability changes Diffusion or leaching of core materials On the basis of that, classified as Degradation controlled monolithic system Diffusion controlled monolithic system Diffusion controlled reservoir system Erosion

8. Types of Microencapsulation: Chemical encapsulation processes: Coacervation (simple, complex) Polymer-polymer incompatibility Polymerization Interfacial polymerization In-situ polymerization Matrix polymerization Mechanical encapsulation processes: Pan coating Spray drying Spray congealing Fluidized bed coater Extrusion & spheronization techniques Rotational suspension separation Solvent evaporation

9. Chemical encapsulation processes Coacervation Phase Separation:

10. Simple coacervation : It can be effected by either by mixing two colloidal dispersions, one having a high affinity for water or it can be induced by adding strongly hydrophilic substances such as alcohol or sodium sulphate . The water soluble polymer is concentrated in water by the action of water miscible, non-solvent for emerging polymer phase. Phase separation can be effected by addition of an electrolyte such as an inorganic salt to an aqueous phase solution of polymer.

11. Complex coacervation : It consist of 3 steps carried out under continuous agitation Step-1: Formation of three immiscible chemical phases A liquid manufacturing vehicle phase A core material phase A coating material phase Methods of phase separation coaervation , By changing the temperature of the polymer solution By adding a salt By adding a non-solvent By adding incompatible polymer to the polymer solution By inducing a polymer-polymer interaction Step-2: Depositing the liquid polymer coating upon core material Step-3: Rigidizing the coating

12. Core material dispersion in solution of shell polymer Separation of coacervate from solution Coating of core material by micro droplets of coacervate Coalescence of coacervate to form continuous shell around core particles

13. Polymer-polymer incompatibility: This method utilizes two polymers that are soluble in a common solvent, yet do not mix with one another in the solution. Polymers form two separate phases, one rich in polymer intended to form the capsules walls, the other rich in the incompatible polymer meant to induce separation of the two phases. The second polymer is not intended to be part of the finished microcapsules wall.

14. Polymerization: The methods involve the reaction of monomeric units located at the interface existing between core material substance and a continuous phase in which the core material is dispersed. Interfacial polymerization In-situ polymerization Matrix polymerization

15. Mechanical encapsulation processes Pan coating: List of variables affecting pan coating:

16. Spray Drying & Spray congealing: It includes: Air heater Atomizing spray chamber Fan Cyclone Product collector Modes of contact of airflow: Co-current Counter- current Mixed flow

17. Fluidized Bed Coater Different types of fluidized bed coater: Top spray Bottom spray Tangential spray.

18. Extrusion & Spheronization: Dispersion of core material in molten carbohydrate mass Extruded into dehydrating liquid for hardening spheronization separation & drying

19. Rotational suspension separation The process involves suspending core particles in a pure, liquefied coating material, then pouring suspension through rotating disk apparatus . The excess liquid between the core particles spreads into very small particles that are separated from product & recycled

20. Solvent Evaporation Advantages of solvent evaporation technique: Simple technique Allows encapsulation of hydrophobic & hydrophilic drug Allows encapsulation of solid & liquid drugs

21. Microencapsulation process with their relative particle size ranges Microencapsulation process Applicable core material Approximate particle size (um) Air suspension Solids 35-5000 Pan coating Solids 600-5000 Multiorifice centrifuge Solids & liquids 1-5000 Coacervation phase separation Solids & liquids 2-5000 Solvent evaporation Solids & liquids 5-5000 Spray drying & congealing Solids & liquids 600

22. Evaluations of microcapsules: Sieve analysis Morphology of microspheres Atomic Force Microscopy Particle Size Polymer solubility in the solvents Viscosity Density determination Capture efficiency Angle of contact In vitro methods Beaker method Dissolution.

23. Applications: Four important areas of microencapsulation applications:

24. Benefits of microencapsulation: Microorganism & enzyme immobilization Protection against UV, heat, oxidation, acids, bases Improved shelf life due to preventing degradation reaction Masking of taste or odors Improved processing, texture and less wastage of ingredients Handling liquids as solids Nutrition food Enhance visual aspects and marketing concepts Textile Industry Pesticides encapsulated to be released overtime Controlled & targeted released of active ingredients. Allows mixing of incompatible compounds Soil inoculation Protection of liquid crystals.

25. Examples of some microencapsulated drugs: Drug/core material Characteristics property Purpose of encapsulation Final product form Acetaminophen Slightly water soluble Taste masking Tablet Aspirin Slightly water soluble Taste masking, SR, reduced gastric irritation, separation of incompatibles Tablet or capsule Menthol Volatile solution Reduction of volatility, SR Lotion Progesterone Slightly water soluble SR Varied Potassium chloride Highly water soluble Reduced gastric irritation Capsule Vitamin A palmitate Nonvolatile liquid Stabilization of oxidation Dry powder

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