Granules and Granulation

Question 1

Powders

Answer 1

Usually a mixture of fine powders, including active ingredient, colours, flavours and sweetening agents

Question 2

Granules

Answer 2

Comprise powder particles that have been aggregated to from large particles sufficiently robust to withstand handling

Question 3

small granules size?

Answer 3

0.2 to 0.4 mm

Question 4

large granules size?

Answer 4

1 to 4 mm

Question 5

define granulation:

Answer 5

processed to adhere to from larger multi-particulate entities

Question 6

Give reasons for granulation:

Answer 6

Loosely packed
Poor flowability
Not uniform
Dusty
Denser
Good flowability
Uniform
Reduce dust

Question 7

Why does granulation occur?

Answer 7

To prevent segregation of the constituents of a powder mix
Particles tend to segregate due to differences in the size, shape and density
To improve the flow properties of the powder mix
To improve compaction properties and uniformity of the mix
To reduce toxic dust
Other reasons
Reduce caking of hygroscopic materials
Increase bulk density, therefore reduce storage volume
Improve appearance of final product

Question 8

Prevention of segregation

Answer 8

Segregation or demixing: small dense particles
to the bottom;
large less dense particles to the top

Granules prevent segregation of the constituents of a powder mix

Question 9

segregation

Answer 9

Particles tend to segregate due to differences in the size, shape and density

Question 10

Flowability

Answer 10

Angle of repose

Question 11

“Bulk density “ (“Do” )

Answer 11

“weight of sample” /”volume of powder when poured into the cylinder”

Question 12

“Tapped density “ (“Df” )

Answer 12

”=” “weight of sample” /”volume of powder after tapping until fully settled”

Question 13

“Carr’s index “

Answer 13

“Df – Do” /”Df” “×100”

Question 14

“Hausner ratio “

Answer 14

“Do” /”Df”

Question 15

Low interparticulate friction

Answer 15

More cohesive powders

Question 16

What is the process of wet granulation?

Answer 16

1) Blend powder = SOLID drug/excipients
2) moist mass = LIQUID; solvent/ binder
3) moist agglomerates = After wet massing, the moist mass is pressed through a sieve or extruder to size the granules
4) dried granules = Primary particles of granules are held together by solid bridges held together by solid bridges upon drying
Bridges of hardening binding agent
Bridges of crystallised drug or excipient
5) sized granules =

Question 17

Cost, stability, los of material, multiple processing steps, incompatibilities

Answer 17

Granulation is an expensive process because of labour, time, equipment, energy and space requirements

may be major concern for moisture-sensitive or thermolabile drugs, as well as those exhibiting polymorphisms

during various stages of processing

add complexity and make validation and control difficult

between formulation components can be aggravated

Question 18

Equipment for wet granulation

Answer 18

High-shear granulation - Mixing, densification and agglomeration achieved through shear and compaction force exerted by the impeller

Fluid-bed granulation - Spraying a binder solution onto a fluidized powder bed

Question 19

Dry granulation

Answer 19

Blend powder
Slug
Granules
Sized granules

Question 20

Ball growth mechanism (each process may overlap):

Answer 20

Coalescence > Breakage
> Layering > Abrasion transfer