Encapsulation and Capsules Flashcards

1
Q

What is the definition of encapsulation, and what are the different encapsulation technologies available?

A

encapsulation is the process in which tiny particles or droplets are surrounded by a coating.

types:
1. nanoencapsulation: used for vaccines, injectable drug delivery systems or imaging-phase contrast
2. microencapsulation: reasonable payload, holds nutrients, enzymes and cells.
3. macroencapsulation: high payload possible, consistent product quality, used for multi-particulate drug delivery.

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2
Q

What are the properties of nanoencapsulation?

A
  • low payload
  • limited protection/stability
  • highly permeable
  • can be prepared by top-down or bottom-up method
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3
Q

What is one application of nanoencapsulation?

A

viable commercial production of polymeric nanoparticles

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4
Q

What are some reasons for encapsulation?

A
  • protection against moisture, oxygen and light
  • prolong shelf-life, increasing stability
  • prevent dose dumping
  • mask undesirable taste, odor or colour
  • convert liquid into solid form (ease of handling)
  • reduce flammability, improving safety
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5
Q

What are some techniques for encapsulation?

A
  1. Emulsification
  2. Spray drying
  3. Fluid bed coating
  4. Extrusion
  5. Coacervation
  6. Solvent change/removal
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6
Q

What are the properties of dripping/extrusion?

A
  • nozzle drips starter seed/capsule containing bioactive substance into inhospitable medium.
  • inhospitable medium coats substance.
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7
Q

What are the properties of coacervation?

A

liquid phase of coating material from a polymeric solution is separated.

  • core particles are encapsulated by a uniform polymeric layer.
  • this is achieved through the manipulation of pH , temperature, solubility and ionic surfactants.
  • e.g. gelatin-gum, gelatin-acacia, gelatin-sodium alginate
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8
Q

What are some advantages and limitations of coacervation?

A

Advantages:

  • uses batch process which is a well-established method
  • wide variety of biopolymers can be used, most common one (gelatin) is easily accessible as well.

Disadvantage:
- require skilful operator/operation

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9
Q

What are the properties of emulsification?

A
  • formation by water-organic solvent mixtures with emulsion

- e.g. sodium alginate solution in iso-octane + surfactants, hardened using calcium chloride

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10
Q

What are some applications of emulsification?

A
  • protects drug from the environment
  • masks unpleasant taste and odour
  • reduce drug volatility
  • reduce gastric irritation by drug
  • controlled drug release
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11
Q

What is macro encapsulation, and what is it used for?

A
- macro encapsulation refers to the coating of cores containing active ingredient to modify drug release (delayed/sustained release), 
as well as to 
- protect drug 
>> taste masking 
>> moisture/gas barrier 
>> UV protection 
>> Add colour
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12
Q

What are the different coated dosage form systems?

A
  1. coated particle : popular in taste masking, stability enhancement
  2. coated pellet: multi-particulate drug delivery system
  3. coated tablet: decorative and identification, enteric-coated
  4. coated capsule: not common, used for enteric or prolonged release
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13
Q

What is a controlled release system?

A
  • release of drug from dosage form that occurs in planned, predictable and slower-than-normal manner.
  • drug is delivered at a specific planned and controlled rate.
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14
Q

What are the advantages of controlled release systems?

A
  • extended daytime and night-time activity of the drug
  • potential for reduced incidence of side effects
  • reduced dosage frequency
  • increased patient compliance
  • potential lower daily cost to patient
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15
Q

What are the different coating processes for pharmaceuticals?

A
  • compression
  • pan coating
  • air suspension
  • spray coating
  • melt coating
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16
Q

What is the design of a sustained drug release pellet?

A
  1. diffusion barrier coating
  2. drug layer: polymer and drug
  3. nonpareil bead (sugar/MCC)
    - nonpareils are used as cores that are coated by drug and polymer, which are obtained from extrusion and spheronization.
    - diffusion barrier coating is made by fluid bed coating.
17
Q

How would you describe pellet coating systems with “envelope” air?

A

Envelope air comes out of nozzle via bottom or side spray, coats substrate bed and minimises local over-wetting.

18
Q

How long does a drug remain in the GI tract?

A

7-10 hours

19
Q

What are the properties of spray drying, and what is it used for?

A
  • liquid containing API is sprayed into a column that contains vents to allow hot air to access and evaporate the liquid, before it cools to become a powder.
  • during the process of spraying small particles can be coated.
  • both suspensions and solutions can be sprayed.
  • used as a simple one-step process to convert liquid solutions into dry powders.
20
Q

What are the advantages of spray drying?

A
  • reduce volume, liquid to dry form
  • ease of dosing, handling and transport
  • improved chemical and biological stability
  • porous and highly specific surface, easy dissolution
21
Q

What can you say about the size distribution for a two-fluid nozzle, a rotary atomiser and a pressure nozzle?

A
  • pressure nozzle: narrow distribution

- two-fluid nozzle: extensively used, middle size distribution

22
Q

What are the different types of capsules?

A
  1. hard gelatin capsules
    - capsule consists of two parts, a cap and a body, that fit one inside the other.
  2. soft gelatin capsule:
    - soft elastic gelatin capsule or softgel that consists of a unit of continuous gelatin shell surrounding a liquid fill material.
23
Q

What are some issues with capsules?

A
  • problems with gelatin:
    1. it is an animal protein and there may be religious sensitivities, may be associated with animal diseases, animal rights and greenhouse gas emission.
    2. moisture-sensitive
    3. properties may change with adsorbed constituents (e.g. aldehydes)
24
Q

How do you determine the fill capacity of hard gelatin capsules?

A
  • Hard gelatin capsules have 5 sizes, popular sizes range from 0-4.
  • capsule fill weight depends on tapped density.
  • capsule fill weight = [tapped density] x [capsule volume]
  • good fill depends on good flow properties of feed.
25
Q

Examples of non-protein based capsules

A

HPMC, alginate

26
Q

What are the tests in which one can evaluate capsule quality?

A
  • assay
  • uniformity of dosage units
  • disintegration
  • dissolution
27
Q

What are the different shapes of soft gelatin capsules?

A

round, oval, oblong, tube

28
Q

What are the advantages of soft gelatin capsules?

A
  • no compression stage, can contain poorly compressible drug
  • liquid fill avoids powder flow and mixing problems
  • prevents oxygen or moisture degradation of drug during long term storage
  • ideal for poorly water soluble drugs
29
Q

What are some things to avoid in the fill content of softgel capsules?

A
  • emulsions (may crack)
  • high concentration of surfactants
  • pH<2.5, hydrolysis of gelatin
  • pH >7.5, gelatin may tan
  • aldehydes, cross-linking or tanning effect