Compaction

Question 1

How are tablets made?

Answer 1

Via compaction

Question 2

How can tableting be done?

Answer 2

by compaction on a tablet press

Question 3

What types of tablet presses are there? (2)

Answer 3

single-station tablet press
- suited for small scale manufacture

multi-station (rotary) tablet press

Question 4

What is compression?

Answer 4

Particles are forced into close proximity, reduced porosity and volume of powder.

Question 5

What is compressibility?

Answer 5

Amenability to compression

Question 6

What is compaction?

Answer 6

Particles cohering to form a solid specimen

Question 7

What is compatibility?

Answer 7

Susceptibility to compaction.

Question 8

Compaction requires

Answer 8

compression

Question 9

Compression may not necessarily result in…

Answer 9

compaction

compaction and compression are two different things.

Question 10

How can particle cohesion be modified?

Answer 10

By formulation.

Question 11

What is the compaction cycle? (3)

Answer 11

how tablets are formed.

1) filling step
- the lower punch is partially inserted from the bottom into the dicavity - where the powder is filled inside. pusher comes in and sweeps off any excess.

2) compression step
- upper punch comes from the top and inserts into the dicavity. both upper punch and lower move to compress the powder. the powder is squeezed into a smaller and smaller space.

3) ejection step
- both upper and lower punches move up and tablet is lifted up and collected by a pusher into a vesicle.

Question 12

Sometimes there is an additional step, what is it and what does it do?

Answer 12

Pre-compression step
same punch movement as compression but gentler and slower.

the aim to expel the majority of air from the powder in the dicavity.

Question 13

What determines whether a powder compacts?

Answer 13

• plastic deformation: the change in shape - this is permanent. It helps the particle to stick.

Question 14

How does Plasticity affect compactibility?

Answer 14

Where deformation increases contact area, plastic deformation prevents elastic recovery.

Question 15

How does Crystallinity affect compatibility?

Answer 15

Amorphous more compatible than crystalline.

Question 16

How does Polymorphism affect compactibility?

Answer 16

More stable polymorph is less compactable.

Question 17

How do Morphology affect compactibility?

Answer 17

Needle-like less compactable than equidimensional.

Question 18

How do Hydrates affect compactibility?

Answer 18

Hydrates more compactable than anhydrous as the water of hydration can act as a plasticiser.

Question 19

What does the compression force affect?

Answer 19

determines whether it compacts but also the tablet volume, porosity, density and tensile strength

Question 20

Porosity is..

Answer 20

a measure of empty spaces in a material.

Question 21

The lower the porosity …

Answer 21

the denser the tablet.

Question 22

What happens as you increase the compression pressure?

Answer 22

region 1 - particles rearrange and fragment
high porosity

region 2 - particles deform plastically
no more room to rearrange

region 3- compact deforms elastically

Question 23

Heckel equation

Answer 23

In (1/e) = KP + A

e - porosity
P - compression pressure
K - constant relating to particle deformation
A - constant relating to particle rearrangement and fragmentation

Question 24

What is the tensile strength?

Answer 24

A measure of how strongly particles stick to each other.

Measure of how much force it takes to break a tablet too - resistance to crushing.

Question 25

What happens if tensile strength is too low and too high?

Answer 25

too low - tablets may crumble before patient even uses correctly

too high - won’t dissolve when patient takes it.

Question 26

How can tensile strength be determined?

Answer 26

a diametric compression test.

a compression force is applied until tablet breaks.

Question 27

How to determine tensile strength for a disc shaped, flat faced tablet:

Answer 27

Ot = 2F / pi dh

Ot = tensile strength
F = tablet fracture force
d = tablet diameter
h = tablet thickness

Question 28

If you want a tablet with the optimum tensile strength..

Answer 28

avoid making them flat or overly round.

Question 29

Face curvature ratio =

Answer 29

d/r

known as rumpf classification