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Phay 6 > W22 Granulation > Flashcards

W22 Granulation Flashcards

1
Q

Definition of granulation

A

A process of size enlargement
- in which particles of varying shape/size are gathered to form larger, uniform, permanent aggregates
- in which the original particles can still be identified

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2
Q

Purpose of granulation (6)

A
  1. To improve flowability
  2. To prevent segregation of the constituents in a powder mix
    (ensure same amount of API + excipients)
  3. To increase bulk density
  4. To reduce dust production (hazard)
  5. To improve/control dissolution rate
    –> disintegrant를 추가하니까
  6. For control of moisture content
    –> heating도 일어나니까
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3
Q

Granulation process

A
  1. API + filler (=diluent) + disintegrant + binder mixed to ==> dry blend
    [Wet Granulation]
  2. Solvent added to dry mix = wet mix
  3. Granulate
  4. Dry to form dry granules ==> dry blend
  5. Lubricant added
  6. Compress into tablet
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4
Q

Wet granulation

A
  1. Preparation
    - Add powders
    - mix with impeller blade to prepare uniform powder mix
  2. Start point
    - Uniform powder mix
  3. Intermediate stage
    - Spray granulation fluid to powder
    - As granulation fluid added, nucleation & growth starts to occur
    - Turn chopper blade on to prevent large granules
  4. Finish point
    - Wet granules placed in oven to cause fluids to evaporate to get dried granules
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5
Q

What holds granules together -during wet granulation process

A

binder solution
two types
1. immobile liquid bridge= monolayer of binder solution
2. mobile liquid bridge = multiple layers of binder solution

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6
Q

What holds granules together - during dried granulation process

A
  1. solid bridges due to
    - hardening of liquid binder
    - recrystallisation
    - spot melting
  2. IMF
  3. surface tension from residual moisture
  4. mechanical interlocking
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7
Q

time progression of granulation

A
  1. mean particle size increases
  2. particle size distribution narrows
  3. granules become closer to spherical
  4. density increases
  5. porosity decreases

mds/dp

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8
Q

How big should granules be?
small tablet
large tablet

A

small tablet < 200mg
- 75-100 microns
large tablet ≥ 600 mg
- larger granules

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9
Q

duration of granulation
- too little granulation fluid
- too much granulation fluid

A
  • undergranulated granule –> very friable
  • overwetted granule –> slurry granules.
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10
Q

How to know when to stop granulation

A
  1. manual determination
  2. pressure detection
  3. light reflectance
  4. humidity measurement
  5. mass temp
  6. conductivity / resistance probs
  7. power consumption
  8. acoustic emission
  9. torque measurement
    –> measure of resistance to rotation
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11
Q

Types of granulators

A
  1. High shear mixer
    - blades and chopper
  2. lower shear granulators
    - oscillating rotor bars
  3. fluid bed granulation
    - air
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12
Q

variables that can be controlled in fluid bed granulatin

A
  1. droplet size
    - atomisation air pressure / volume
    - spray rate
  2. Evaporation rate
    - inlet air temp
    - RH
    - dew point
    - air volume
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13
Q

Dry granulation process

A
  1. mix drugs and excipients
  2. compress to form a big lump
  3. grind big lump to produce dry granules
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14
Q

Dry granulation techniques

A
  1. Roller compaction
    - powder feeder
    - rotating rolls breaking
    - granules produced
  2. slugging
    - hammer
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15
Q

Wetting apparatus four equipments

A
  1. Impeller blade = rotates slowly (= mixes powder mix)
  2. Chopper blade = sharper & rotates faster than impeller blade (= prevents granules getting too big)
  3. Granulation fluid = either water (dry binder) OR solution of water + binder (wet binder)
  4. Spray nozzle = sprays granulation fluid onto powder
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16
Q

Dried granules

A
  1. porous structure
  2. solid bridges between particles - after binding solution surrounding the particles evaporate
  3. greater porosity gives faster dissolution but weaker granules
17
Q

Fluid bed granulation
- (1 ) causes granules to move around in air rather than (2 )
- (3) added into air
- mixes until end of granulation
- measured by (4 and 5), cannot measure using (6) as there is no. (7)
- (8) prevents dust escaping

A
  1. air
  2. blade
  3. granulation fluid
  4. temperature
  5. humidity
  6. torque - measure of resistance to rotation
  7. blade
  8. exhaust filter
18
Q

Pros (4) and cons of wet granulation

A

Pros
1) increase granule strength - hard, not friable, easy to coat
2) can use with wide range of API concentration – useful for API with poor flow properties
3) uniform distribution of API and colours - create range of colour intensity
4) prevents component de-mixing (segregation)

cons
1) many stages = higher chance for things to go worng
2) long, expensive, requires large space
3. heat/water sensitive drug cannot
4. safety issues with organic solvents - evaporate to create gas
5. potentially hazardous dust
6. risk of migration of soluble components to granule surface (water moves from inside to outside when drying, carrying components )

19
Q

Dry granulation pros and cons

A

pros
1) less equipment, cheaper, no expensive drying process
2) no binder solution
3) no heat and liquid - so heat/water sensitive API can
4) overcome some morphology issues found with powders

cons
1) nultiple processing steps
2) mixing can be problematic - less consistant balance between drug and excipients
3. poor powder flow
4. no solid bridges - non porous, weaker
5. colour distribution poor
6. dust production- hazardous
7. final tablets softer than wet
8. harder to coat

20
Q

pros and cons of low shear granulators

A
  • high fluid
  • longer process
  • loss of materials occurs
  • cheaper equipment than high shear mixer
21
Q

Examples of binder

A
  1. sucrose
  2. starch
  3. PVP
  4. celluloses (HPMC)
  5. Gelatin
22
Q

Properties of binders

A
  1. cohesive
  2. inert
  3. easily blended
  4. non-hydroscopic = don’t suck moisture from air
23
Q

wet granulation process

A
  1. powder + binder droplets
  2. liquid bridge
  3. solid bridge
  4. snowball structure
24
Q

how to measure the particle size & create a graph

A
  1. powder containing particles w/ various size range is poured through the stack of sieves
  2. the frequency of particle size can be represented through a cumulative frequency diagram
    - get cumulative frequency undersize & oversize
  3. plot a cumulative frequency graph

Phay 6 (8 decks)

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