Granulation

Question 1

What are granules?

Answer 1

Aggregates of powder particles

Question 2

What are granules for?

Answer 2

Oral administration

Question 3

What are the different types?

Answer 3

Effervescent, coated + gastro-resistant

Question 4

What is the size of granules?

Answer 4

200-4000 μm

Question 5

What are the pros?

Answer 5

Better handling
Less likely to segregate
Better compaction characteristics
Reduced fines
Higher bulk density

Question 6

Why is segregation less likely?

Answer 6

Particle size more uniform

Question 7

What are the cons?

Answer 7

Addition processing = increases cost
Instability during granulation

Question 8

What does particle aggregation result in?

Answer 8

Particle size enlargement

Question 9

What does particle aggregation require?

Answer 9

Powder ingredients
Binder
Equipment

Question 10

Wet granulation

Answer 10

Shear granulation
Fluidised-bed granulation

Question 11

Dr granulation

Answer 11

Slugging
Roller compaction

Question 12

What is the process?

Answer 12

Mix
Aggregate using suitable binder
Dry granules
Sieve to select particle size

Question 13

What type of binder is used for wet granulation?

Answer 13

Solution

Question 14

What type of binder is used for dry granulation?

Answer 14

Solid

Question 15

What is example of wet binder?

Answer 15

Amorphous polymers

Question 16

What do solubility of granules depend on?

Answer 16

Type, amount + solubility of binder

Question 17

What are examples of amorphous polymers?

Answer 17

Starch (5-15% w/w)
Gelatin (1-3% w/w)
PVP (3-3% w/w)
Cellulose ethers (1-5%)

Question 18

What is intragranular bonding?

Answer 18

Attractive forces between particles
Attractive forces between immobile films
Liquid bridges
Solid bridges
Mechanical interlocking

Question 19

What is the classification for intragranular bonding?

Answer 19

Rumpf

Question 20

When is there liquid bridges?

Answer 20

Wet granulation

Question 21

When is there solid bridges?

Answer 21

Dry granulation
= sintering of solid binder OR re-crystallisation of liquid binder

Question 22

When is there mechanical interlocking?

Answer 22

Shape-related bonding
= rough angular particles

Question 23

What are the stages of granulation by wet granulation?

Answer 23

Wetting + nucleation
Consolidation + coalescence = particles grow
Attrition + breakage = particles too large = broken down

Question 24

Describe wetting + nucleation

Answer 24

Wetted by binder solution = nuclei formed
Sprayed = uniform wetting

Question 25

What are important factors for wetting + nucleation?

Answer 25

Droplet size, wetting properties + particle flux in wetting zone

Question 26

Describe consolidation + coalescence

Answer 26

Other particles collide with nuclei, deform + adhere

Question 27

What are important factors in consolidation + coalescence?

Answer 27

Particle surface moisture, particle hardness + particle velocity

Question 28

Describe attrition + breakage

Answer 28

Fine particles shed from dry granule surface (attrition)
Dry granules break up

Question 29

What are important factors in attrition + breakage?

Answer 29

Particle velocity + granule porosity

Question 30

Describe shear granulator
(Wet granulation)

Answer 30

Perform low-shear granulation from wet mass
Vessel with impeller + chopper (rotate at right angle to each other)
Binder solution injected