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Questions and Answers
Microencapsulation only involves liquid materials.
Microencapsulation only involves liquid materials.
False
The diameters of micro particles can range from 50 to 5000 microns.
The diameters of micro particles can range from 50 to 5000 microns.
True
Particles larger than 1000µm are termed micro particles.
Particles larger than 1000µm are termed micro particles.
False
One reason for microencapsulation is to convert liquid active components into a dry solid system.
One reason for microencapsulation is to convert liquid active components into a dry solid system.
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Microencapsulation cannot help in isolating core substances from their surroundings.
Microencapsulation cannot help in isolating core substances from their surroundings.
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Microspheres are solely made from synthetic polymers for drug delivery systems.
Microspheres are solely made from synthetic polymers for drug delivery systems.
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Microencapsulation can enhance the toxicity of a drug.
Microencapsulation can enhance the toxicity of a drug.
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Microencapsulation can convert liquid core materials into solid form.
Microencapsulation can convert liquid core materials into solid form.
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The coating material must be reactive with the core material to be effective.
The coating material must be reactive with the core material to be effective.
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Microencapsulation can mask the taste or odor of core materials.
Microencapsulation can mask the taste or odor of core materials.
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One of the goals of microencapsulation is to achieve targeted drug release.
One of the goals of microencapsulation is to achieve targeted drug release.
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A high viscosity is a desired property for coating materials used in microencapsulation.
A high viscosity is a desired property for coating materials used in microencapsulation.
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Coating material must always be aqueous to achieve effective microencapsulation.
Coating material must always be aqueous to achieve effective microencapsulation.
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The core material of microencapsulation can consist of solid, liquid, or gas.
The core material of microencapsulation can consist of solid, liquid, or gas.
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Microencapsulation has no role in increasing the bioavailability of drugs.
Microencapsulation has no role in increasing the bioavailability of drugs.
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Polymers used in microencapsulation can have a single linear structure only.
Polymers used in microencapsulation can have a single linear structure only.
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Air suspension techniques improve control and flexibility compared to pan coating.
Air suspension techniques improve control and flexibility compared to pan coating.
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Agglomeration of particles during air suspension techniques results in smaller particle sizes.
Agglomeration of particles during air suspension techniques results in smaller particle sizes.
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Microencapsulation can potentially increase the bioavailability of a drug.
Microencapsulation can potentially increase the bioavailability of a drug.
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All dosage forms can be microencapsulated using the same technique.
All dosage forms can be microencapsulated using the same technique.
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The co-acervation process results in the formation of three immiscible phases.
The co-acervation process results in the formation of three immiscible phases.
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The desolvation step is crucial during the co-acervation process.
The desolvation step is crucial during the co-acervation process.
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Coating thickness depends solely on the size of the core material.
Coating thickness depends solely on the size of the core material.
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Microencapsulation can improve patient compliance through controlled drug release.
Microencapsulation can improve patient compliance through controlled drug release.
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Hygroscopic drugs typically have an extended shelf life.
Hygroscopic drugs typically have an extended shelf life.
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Volume of air is not a significant variable in the air suspension techniques for microencapsulation.
Volume of air is not a significant variable in the air suspension techniques for microencapsulation.
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The use of microencapsulation techniques is cost-effective.
The use of microencapsulation techniques is cost-effective.
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All core materials used must have a melting point below room temperature for effective microencapsulation.
All core materials used must have a melting point below room temperature for effective microencapsulation.
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Continuous and uniform film formation is a common challenge in microencapsulation.
Continuous and uniform film formation is a common challenge in microencapsulation.
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Pan coating is considered more effective than air suspension techniques in terms of flexibility.
Pan coating is considered more effective than air suspension techniques in terms of flexibility.
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The process of co-acervation results in the formation of a polymer-rich phase known as a co-acervate.
The process of co-acervation results in the formation of a polymer-rich phase known as a co-acervate.
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Microencapsulation by spray-drying is primarily intended for the encapsulation of solid particles.
Microencapsulation by spray-drying is primarily intended for the encapsulation of solid particles.
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Spray drying produces microcapsules that are generally larger than 100µm in size.
Spray drying produces microcapsules that are generally larger than 100µm in size.
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Desolvation involves the removal of solvent from the polymer solution, which can initiate co-acervation.
Desolvation involves the removal of solvent from the polymer solution, which can initiate co-acervation.
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The hardening of the coat material in microencapsulation can only be achieved through temperature reduction.
The hardening of the coat material in microencapsulation can only be achieved through temperature reduction.
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In the context of spray drying, the initial step involves atomization of the core particles.
In the context of spray drying, the initial step involves atomization of the core particles.
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Coating material is deposited on liquid droplets rather than solid particles during the microencapsulation process.
Coating material is deposited on liquid droplets rather than solid particles during the microencapsulation process.
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Crosslinking is one of the methods that can harden the coat material in microencapsulation.
Crosslinking is one of the methods that can harden the coat material in microencapsulation.
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Change in pH has no effect on the solubility of polymers during the co-acervation process.
Change in pH has no effect on the solubility of polymers during the co-acervation process.
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Spray-drying involves spraying a polymer solution into a cold chamber to solidify the shell material.
Spray-drying involves spraying a polymer solution into a cold chamber to solidify the shell material.
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Study Notes
Industrial Pharmacy - Lecture 8: Microencapsulation Technology
- Microencapsulation is a process that coats tiny droplets or particles of liquid or solid material with a continuous polymer film.
- It creates capsules ranging from less than one micron to several hundred microns in size.
- It is used to apply thin coatings to tiny particles of solids, liquids, or even gases.
- Particle size typically ranges from 50 to 5000 microns.
- Microencapsulation has two main phases:
- Core material (the substance being coated)
- Coating material (the protective polymer layer)
- The products of this process are microparticles, microcapsules, microspheres, coated granules, and pellets.
- Particles between 3 and 800 µm are called microparticles or microcapsules or microspheres.
- Particles larger than 1000 µm are called macroparticles.
Microencapsulation: Introduction
- Microencapsulation is a method to coat or encapsulate one substance inside another substance.
- This could be used to create controlled-release drug delivery systems.
- This technique allows the careful targeting of drugs to specific tissues.
- This helps to reduce the side effects and maximize the benefits by controlling the release of the drug.
- A well designed controlled drug delivery system overcomes some problems of conventional therapy.
- Enhances the efficacy of a drug by delivering it to target tissues in the optimal amount and time.
- This method minimizes toxicity and minimizes side effects.
Reasons for Microencapsulation
- Protects reactive substances from environmental factors.
- Converts liquid active components into a dry solid system.
- Separates incompatible components for various functional reasons.
- Protects the immediate environment of the microcapsules from the active components.
- Isolates the core material from surroundings e.g. isolating vitamins from oxygen.
- Protects from chemical attack
- Offers safe handling of toxic materials
- Allows controlled release to achieve targeted drug action (e.g., timed or sustained release).
- Masks undesirable tastes or odors.
- Enhances bioavailability
Fundamental Considerations of Microencapsulation
-
Microparticles typically consist of two components.
- Core material: a mixture of active ingredients, stabilizers, diluents, excipients, and release-rate modifiers.
- Coating material: compatible, non-reactive components that provides desired characteristics like strength, flexibility, impermeability, optical properties, non-hygroscopicity, and stability.
-
Core material can include active ingredients, stabilizers, diluents, excipients, and release-rate modifiers.
-
Coating material (shell) needs to be compatible, non-reactive, and provide properties like strength, flexibility, impermeability, optical properties, non-hygroscopicity, and stability.
Coating Material Properties
- Coating material needs to stabilize the core material.
- It should be inert to active ingredients.
- Allow controlled release rates.
- Be film-forming, tasteless, and stable in nature.
- Be non-hygroscopic and have minimal viscosity for economical reasons.
- Be capable of dissolving in aqueous media, solvents, or through melting processes.
- It can possess flexibility, thinness, etc.
- Coating thickness depends on coating-to-core ratio and particle size of core material.
Types of Coating Materials
- Water-soluble resins (e.g., gelatin, gum arabic, methyl cellulose)
- Water-insoluble resins (e.g., ethyl cellulose, cellulose nitrate, silicones)
- Wax and lipid coatings (e.g., paraffin, carnauba wax, stearic acid)
- Enteric coatings (e.g., shellac, zein, cellulose acetate phthalate)
Advantages of Microencapsulation
- Increased bioavailability.
- Altered drug release.
- Enhanced patient compliance.
- Targeted drug delivery
- Reduced reactivity of the core material.
- Reduced rate of evaporation from the core material.
- Conversion of liquid to solid form.
- Masking taste and odor of the core material.
Disadvantages of Microencapsulation
- High cost of microencapsulation techniques
- Difficulty encapsulating diverse dosage forms in a single process
- Potential non-uniform coating and variations in release pattern
- Potential cross-reactions between core and shell materials in some cases.
- Reduced shelf life of hygroscopic drugs.
Microencapsulation Techniques
- Air Suspension techniques (used to create spherical particles)
- Air suspension, centrifugal extrusion, pan coating, spray-drying, mixed-flow spray drying.
- Co-acervation process (based on phase separation):
- Preparing dispersion of core material in a homogeneous coating polymer solution.
- Desolvating, leading to polymer-rich phase and solvent phase.
- Coating polymer deposition on core material.
- Hardening of coating (desolvation, pH changes, temperature changes, gelation, etc.)
- Solvent Evaporation Process:
- Forming a solution/dispersion of the drug into an organic polymer phase
- Adding into the aqueous phase and forming o/w emulsion to create suitable stabilizer
- Removing the solvent to make microspheres.
- Pan Coating
- Spray-drying & congealing
Applications of Microencapsulation
- Taste-masking (e.g., acetaminophen)
- Sustained release (e.g., aspirin)
- Conversion of liquids to solids (e.g., clofibrate)
- Odor masking (e.g., castor oil)
- Reduced gastric irritation (e.g., phenylbutazone)
- Oxidation stability (e.g. vitamin A palmitate)
Conclusion
- Microencapsulation offers advantages in terms of protection, masking, controlled release, and easier handling of drug materials.
- It enables accurate delivery of small quantities of potent drugs.
- Protects drug compounds for improved delivery.
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Description
Explore the essential concepts of microencapsulation, including its role in drug delivery systems and the physical characteristics of micro particles. This quiz addresses core materials, coating requirements, and the benefits of microencapsulation in enhancing drug effectiveness. Test your knowledge on the techniques and applications associated with this innovative pharmaceutical process.
