Granulation

Question 1

What is granulation?

Answer 1

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

Question 2

Why granulate?

Answer 2

• 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

Question 3

What are the requirements for granules?

Answer 3

• 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

Question 4

What are the 2 types of granulation?

Answer 4

Wet granulation
Dry granulation

Question 5

Describe wet granulation

Answer 5

Powder + liquid mix
Granules formed
Dried
Sieved

Question 6

Describe dry granulation

Answer 6

Slugs or compacts formed from dry powder
Coarse grinding
Sieved

Question 7

What are the mechanisms for dry granulation formation?

Answer 7

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

Question 8

What are the mechanisms of wet granulation formation?

Answer 8

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

Question 9

What are the possible mechanisms of ball growth?

Answer 9

• 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

Question 10

What are the types of wet granulation?

Answer 10

Low shear mixer
High shear mixer granulation
Fluidized bed granulator

Question 11

Describe the low shear mixer

Answer 11

• 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

Question 12

Describe shear mixer granulation

Answer 12

• 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

Question 13

Describe the fluidized bed granulator

Answer 13

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

Question 14

What are the things that affect granules in fluiddized bed?

Answer 14

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

Question 15

What are the 2 types of dry granulation?

Answer 15

Roller compaction
Slugging

Question 16

Describe roller compaction

Answer 16

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

Question 17

Describe slugging

Answer 17

Tablet press
need a lubricant