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Form & Tech CA3 Rev > Encapsulation and capsules > Flashcards

Encapsulation and capsules Flashcards

1
Q

benefits of using pellet coating systems with envelope air

A

Minimise local overwetting
Pattern spray dispersion
Protect the spray (prevent particles from getting stuck on the nozzle)

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2
Q

Microencapsulationn

A

Process which tiny particles/droplets surrounded by coating

2 types:

  • Reservoir: core covered by shell – drug release controlled by barrier property of shell
  • Matrix: consist of drug dispersed in matrix – drug release controlled by surface area available for release – release of drug is 1st order, thus formulation must be able to erode to form a pseudo zero order system
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3
Q

Types of encapsulation technologies:

A

nano: imaging phase contrast, injectables, vaccine
micro: reasonable payload, holding nutrients, enzymes, cells – offers protection, diffusion barrier
Macro: high payload possible, consistent production quality, multi-particulate drug delivery system

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4
Q

Methods for nanoencapsulation

A

Top down:

  • milling/shreading/grinding
  • homogenisation/extrusion

Bottom up methods:

  • Antisolvent precipitation
  • Coacervation (temp/salt/pH): liquid liquid phase separation
  • Drying
  • formation of inclusion complex
  • fluid gel particle formation (shear and gelation)
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5
Q

traits of nanocapsules:

A

low payload, limited protection and stability, highly permeable

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6
Q

Encapsulation materials:

A

Particles
Modified biopolymers
Synthetic (co) polymers
low MW molecules

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7
Q

Functional ingredients frequently encapsulated:

A 
Probiotics 
sensitive fatty acids 
antioxidants 
vitamins
flavours, aromas, colorants 
drug like components
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8
Q

Release trigger of capsules:

A 
pH
Mechanical stress
Enzymes 
Ultrasound 
Temperature 
Ionic strength 
Light
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9
Q

Encapsulation techniques:

A 
Emulsion based: pickering, self-assembling, layer by layer 
Spray drying 
dipping (slide 10)
fluid bed coating 
extrusion 
coacervation 
solvent change/removal
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10
Q

Need for encapsulation

A
  • protection against moisture, oxygen and light
  • prolonged shelf life (confer stability)
  • prevent premature release and pre reaction
  • mask undesirable taste, odour and/or colour
  • provide controlled release
  • convert liquid into solid – for handling
  • Reduce flammability
  • Increase safety and handling
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11
Q

Dipping/extrusion:

A

Dripping of droplets of pellet material into a medium where the material will not be soluble in using a nozzle – air used to break up the string of liquid

can have formation of different sizes

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12
Q

coacervation:

A

Separation of liquid phase of coating material from polymeric solution and ecapsulating core particles by uniform polymeric layer

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13
Q

Traits of coacervation:

A

Well established method, batch process
Require skillful operator
often contains gelatin
use in: carbonless paper, pesticide fragrances, liquid crystals, detergents, paint stabilisers, adhesives

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14
Q

Emulsification method:

A

Formationn by water-organic solvent mixtures with surfactants

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15
Q

Uses of emulsification method:

A 
protect drug from environment 
Mask unpleasant taste and odour 
decreased drug volatility 
decreased gastric irritation by drug 
separates incompatible components 
control drug release 
production of chemoembolisation agents 
production of microbioreactors
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16
Q

Macroencapsulation:

A

Coating of cores containing active ingredient

  • modification of drug release (delayed/sustained)
  • Protection of drug (taste masking, moisture/gas barrier, UV protection, add colour)
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17
Q

Coated dosage form systems:

A

Coated particle: taste maskig, stability enhancement
coated pellet: multiparticulate drug delivery system, multi unit pellet system tablet
coated tablet: decorative and identification, eteric coated, sustained release coated, osmotic pump
coated capsule : non common, enteric/prolonged release

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18
Q

Traits of controlled release systems:

A
  • Extended daytime and nighttime activity of drug
  • Potential for reduced incidence of side effects
  • Reduced dosage frequency
  • Increased patient compliance
  • Potential lower daily cost to patient (fewer dosage units)
19
Q

Coating process for pharmaceuticals:

A
  1. Coating: specialised tablet press with capability of multilayer compression
  2. Pan-coating: popular and well established method to coat tablets
  3. Air suspension: wurster coating used for coating pellets
  4. spray coating: spray dryers used to convert liquid feeds to dry powders
  5. melt coating: hot melt extrusion/spray congealing
20
Q

Design strategies:

A
  • non pareils used as cores to be layered with drug and then coated with diffusion barrier polymer coat
  • Drug loaded pellets prepared by extrusion spheronisation then overcoated with diffusion barrier polymer coat
21
Q

Production steps by extrusion-spheronisation:

A
  1. dry blending
  2. wet massing
  3. extrusion
  4. spheronisation
  5. drying
  6. coating
22
Q

Fluid bed drying and coating types:

A

Top spray
bottom spray
side spray
drying

23
Q

Top spray coating:

A

use countercurrent system

  • air moves upwards – smaller particles preferentially coated
  • used more for granulation than coating – coating efficiency inferior to bottom/side spray systems
24
Q

Bottom spray system:

A

draw in pellets from the side and all will be effectively coated efficiently as particles are effectively in a queue

25
Q

Side spray coating:

A

Efficient coaters for paticles and air flow will swirl pellets around

26
Q

Pellet coating systems with ‘envelope’ air

A

3 component nozzle

Air around spray nozzle extend spray into coating substrate bed
movement of particles is spiral

27
Q

Repeat action preparations:

A

pellets with pulsatile release coatings for sustained overall response

28
Q

Limitations of GIT on sustained release

A

absorptive phase max 8-10h – at best BD dosing

pellets can pass closed pylorus port and thus drug release will not be dependent on gastric emptying time

29
Q

Spray drying:

A

convert solutions, suspension/emulsions to dry powders in a 1 step process

30
Q

Advantages of spray drying:

A

highly efficient and versatile
fast and continuous drying process
can be established on large industrial scale
liquid can be converted to dry form – reduced volume
allow for ease of dosing, handling and transport
improved chemical and biological stability
defined shape and size
porus and high specific surface for easy dissolution

31
Q

Preparation of spray dried microparticles:

A
  1. spraying of suspensions: insoluble active in solution of shell material
  2. Active and shell material added as liquid
32
Q

functional principle of spray drying:

A
  1. atomised droplets added and comes into contact with hot drying gas
  2. dry surface formed
  3. Particle type formed:
    - Solid particle
    - shrivelled particle
    - hollow particle
    - cenosphere
    - particle distribution
33
Q

nozzle designs for spray drying

A

Two-fluid (air+feed) – largest particle size distribution
Three-fluid (2 samples+air)
Ultrasonic (vibration of nozzle)
Pressure – smallest particle size distribution
Rotatory atomiser (cooling air, feed, rotating spindle, purge gas)

34
Q

Examples of spray dryers:

A

laboratory
small scale, pilot
pilot scale small
production scale

35
Q

Spray prilling (congealing)

A

Cold air used to dry – confined to smaller sizes

36
Q

uses of spray prilling:

A

prepare meltable powders (lubricants) , taste masking, controlled release products
0.2-1.5 mm range

37
Q

Issues with capsules:

A

Gelatin used as raw material

  • animal protein – religious concerns, association with animal diseases
  • moisture sensitive
  • properties may change with adsorbed constituents
38
Q

Fill capacity of capsules (hard)

A

fill weight depends on tapped density (size 000(1.36 mL)-5 (0.15 mL))(largest to smallest)

Size 2 most commonly used: 0.37 mL

capsule fill weight = tapped density * capsule volume

can have self-locking mechanism

Good fill depends on good flow properties of feed

39
Q

Non-protein based capsules (alternatives to gelatin)

A

hydroxyproplymethyl cellulose (HPMC)
Pullulan
HPMC and carrageenan
Alginate

40
Q

Tests for capsule quality:

A

Hard gelatin capsules:

  • Assay (quality of the capsule itself) – moisture permeability
  • uniformity of dosage units
  • disintegration
  • dissolution
41
Q

Traits of soft gelatin capsules:

A
  • no compression stage, can contain poorly compressible drug
  • liquid fill avoid problems with powder flow and mixing
  • avoid oxygen/moisture degradation of drug during long term storage
  • For poorly water soluble drugs in liquid vehicle emulsified in GIT as fine droplets
42
Q

Fills avoided in soft gelatin capsules:

A
  • Emulsions (may crack in capsule)
  • Surfactants (affect gelatin integrity)
  • pH<2.5 (gelatin hydrolyses)
  • pH > 7.5 (tanning effect on gelatin)
  • Aldehydes (forms cross linking with gelatin and may have tanning effect)
43
Q

Bioavailability from capsules:

A

Dissolution of gelatin shell disperses content into intestinal liquid – bioavailability should be good (similar to liquid, powder, granule preparations)
Discharge of capsule content depends on flow of materials within – problematic for hydrophobic materials – need to add surface active agent to aid wetting/discharge

Form & Tech CA3 Rev (10 decks)

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