Granulation Flashcards

1
Q

What is granulation?

A

Size enlargement of powders, powders will adhere to make granule. Often used as an intermediate in tablets and capsules.

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2
Q

Why granulate?

A
  • Segregation; better uniformity
  • Flow; same shape, size helps flow
  • Compressibility; better for tabs formation
  • Densification; take up less volume
  • Dust hazard; no powder everywhere
  • Wettability of poorly soluble drugs; mixing with hydrophilic excipients
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3
Q

What are the requirements for granules?

A
  • Similar shape and colour
  • Mechanical strength
  • Moisture content 3-5% w/w
  • Disintegrate into original powder
  • Flow
  • Particle size is uniform
  • No more than 10% w/w
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4
Q

What are the 2 types of granulation?

A

Wet granulation
Dry granulation

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5
Q

Describe wet granulation

A

Powder + liquid mix
Granules formed
Dried
Sieved

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6
Q

Describe dry granulation

A

Slugs or compacts formed from dry powder
Coarse grinding
Sieved

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7
Q

What are the mechanisms for dry granulation formation?

A
  1. Particles adhere to each other when pressure is applied.
  2. Held together using Van de Waals forces because of small size.
  3. Think of a snow ball - push together hold shape
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8
Q

What are the mechanisms of wet granulation formation?

A
  1. Mix liquid and powder together
  2. Nucleation; small number of particles combine to form pendular state
  3. Add more liquid = capillary state
  4. Continue - ball growth - too large
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9
Q

What are the possible mechanisms of ball growth?

A
  • Layering; layer powder added to the granule
  • Coalescence; join to make larger one
  • Breakage; broken parts adhere to granule
  • Abrasion; granule hit each other and break , then can be attache to other granules
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10
Q

What are the types of wet granulation?

A

Low shear mixer
High shear mixer granulation
Fluidized bed granulator

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11
Q

Describe the low shear mixer

A
  • Powder and binder solution mixed in planetary mixer
  • After mixing, mass is out into a granulator
  • Then sieved into desired size
  • Dried in try oven
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12
Q

Describe shear mixer granulation

A
  • Mixer bowl with impeller and chopper
  • All in one machine
  • Dry powder mixed by impeller
  • Add liquid and mix impeller
  • Chopper will form granules from the wet mass
  • Granules are formed and pushed through sieve to be dried in fluidised bed
  • Easy and quick
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13
Q

Describe the fluidized bed granulator

A
  • Air blown through powder bed to fluidize and mix
  • Spray nozzle sprays the binder onto the powder
  • Temp - to solidify the granules
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14
Q

What are the things that affect granules in fluiddized bed?

A

Air pressure
binder conc and type
particle size
granulation, drying and temp time

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15
Q

What are the 2 types of dry granulation?

A

Roller compaction
Slugging

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16
Q

Describe roller compaction

A

Preferred
- 2 rollers apply stress
- fillers/binder used: MCC and lactose
Must control; roll pressure, speed, feeding rate of powder
- poor tensile strength - brittle

17
Q

Describe slugging

A

Tablet press
need a lubricant