Pellets and Extrusion

Question 1

What are pellets?

Answer 1

Dense spherical agglomerates of particles

Commonly formed granules

Question 2

What is an example of a pellet?

Answer 2

Omeprazole (PPI)

Question 3

What are similarities of pellets and granules?

Answer 3

Can contain multiple drugs and excipients
Can be coated individually for modified release
Commonly filled into capsules or pressed into tablets
Possbile to manufacture incompatible ingredients into a dosage form
Smaller than tablets and capsules

Question 4

Why is disintegration not needed?

Answer 4

Large SA

Question 5

What are the advantages of pellets? (6)

Answer 5

1) Greater density
2) Better flow properties
3) Lower friability
4) Narrower particle size distribution
5) More uniform packing
6) Smoother surface for more uniform coating

Question 6

How are pellets made?

Answer 6

Extrusion-sphrenoisation

Question 7

What steps are involved in extrusion-spheronisation?

Answer 7

1) Agglomeration
2) Extrusion
3) Pelletisation
4) Spheronisation

Question 8

What is extrusion?

Answer 8

Semi-solid material, like playdough

Question 9

What is extrusion?

Answer 9

Semi-solid material, like playdough forcing material through a tiny hole (toothpaste)
Usually elongated cylindrical

Question 10

What are the 4 types of extruder?

Answer 10

1) Screw extruder
2) Sieve / basket extruder
3) Roll extruder
4) Ram extruder

Question 11

What are the parameters of extrusion?

Answer 11

1) Material flow properties
2) Screen gemotries and dimensions
3) Extrusion speed
4) Extruder temperature

Question 12

How do spheronisers shape pellets?

Answer 12

Cause the particles to collide with the spheroniser wall, with the friction plate and with each other, the so-called roping movement.

Question 13

What are the two patterns of the friction plate-pattern?

Answer 13

Cross-hatch (COMMON)

Radial pattern gentler but unsuitable for large disc diameters

Question 14

Why are cross-hatch more common?

Answer 14

more uniform

Question 15

What are the mechanisms of spheronisation?

Answer 15

1) Plastic deformation
2) Dumb-bell breakup
3) Attrition-agglomeration

Question 16

What are the 3 spheronisation parameters?

Answer 16

Rotational speed
Fill volume/mass - particle movement space
Residence time (machine operation time)

Question 17

What are the pellet properties?

Answer 17

Particle size
Particle shape
Surface morphology 
Friability
Tensile strength
Density
Porosity
Disintegration time
Dissolution time