Tableting

Question 1

Causes of capping:

Answer 1

air entrapment 
mechanism of volume reduction 
compression speed 
viscoelastic recovery 
stress and density distribution 
internal shear stress

Question 2

Remedies for capping:

Answer 2

lower compression force 
reduce compression speed 
decrease ejection path in die 
tool design change 
extend dwell time

Question 3

methods to make tablets:

Answer 3

compression
moulding
printing

Question 4

Properties of tablets:

Answer 4

contain exact dosage of active principles
confer maximum stability possible 
possess suitable mechanical properties 
contain only inert additives/excipients 
aesthetically pleasing 
suitable for intended purpose

Question 5

Advantages and disadvantages of tablet as a dosage form

Answer 5

Advantages: 
- convenient means of administering 
- delivery of an accurate dose 
- small and compact 
- easy to handle and pack 
- high production throughput possible 
Disadvantages: 
- poor compressibility
- poor wetting 
- slow dissolution 
- high dose 
- bitter taste/bad odour 
- sensitivity to moisture

Question 6

types of excipients:

Answer 6

Major: 
Diluent/filler
binder/adhesive
disintegrant 
lubricant 

Minor: 
absorbant 
stabiliser 
wetting agent 
colorant

Question 7

properties of diluents/fillers:

Answer 7

inert, inexpensive, good flow, good compactibility

Question 8

Types of diluents/fillers:

Answer 8

sugars, starches, celluloses, inorganic salts

Question 9

types of binders/adhesives

Answer 9

celluloses: high strength, low friability, self-lubricant, dry binder
Modified celluloses: dissolved in water and used as liquid binders
synthetic polymers: not absorbed, also used to reduce viscosity of blood, one of the most popular and safe for human consumption
Gums: not as color stable

Question 10

Types of disintegrants and their mechanisms:

Answer 10

Starch (2-10%): swelling and wicking
MCC (5-10%): wicking, H-bonding
Sodium starch glycolate (1-5% w/w): swelling
Crospovidone (2-5%): wicking, strain recovery

Question 11

Mechanisms of disintegrants:

Answer 11

Swelling: swelling of the materials to push particles apart
Wicking: Helps matrix become softer and allow other things present inside to swell – commonly used with other types of disintegrants
Strain recovery: compressed when compacted and return to normal state when put in liquid
interruption of particle-particle bonds: water reduces bonds holding tablet together
Heat of interaction:enthalpy change releases heat of interaction that helps to break bonds

Question 12

Types of lubricants:

Answer 12

Glidants:
Improve flow properties of granules/powders by reducing friction between particles –> ball bearing effect
Lubricants:
reduce friction between granules and die wall during compaction –> forms films on surface
Anti-adherents:
prevent sticking/adhesion of tablet, granules/powders to faces of punches – allow tablet to be separated from die cavity

Question 13

Forms of lubricants:

Answer 13

Hydrodynamic – fluid type sprayed into mixture

Boundary – can be water insoluble or water soluble

Question 14

tableting operation of single punch tablet machine

Answer 14

1. lower punch in die moves down to create die cavity for granules
2. shoe moves over die and fills cavity, scrapes excess granules to level of die table by moving aside
3. upper punch descends to compress granules
4. upper punch withdraws, lower punch rises to eject tablet
5. Shoe shifts tablet to collection chute
6. Cycle repeats

Question 15

Tableting operation of rotatory/multistation tablet machine

Answer 15

1. dies on rotating platform (turret)
2. each die with upper and lower punches
3. Granules from hopper into feed frame covering number of dies
4. Lower punch descends, allowing die filling to desired weight+excess
5. Lower punch raises to correct level, excess granules removed
6. Punches brought to compress granules into tablet

Question 16

Tabletability

Answer 16

capacity of powdered material to be made into tablet of specific strength under effect of compression pressure

Question 17

Compressibility

Answer 17

Ability to undergo volume reduction when subjected to applied pressure

Question 18

compactability

Answer 18

Ability of material to produce tablets with sufficient strength under effect of densification

Question 19

Attributes of good tablet:

Answer 19

contain correct amount of actives 
possess good mechanical properties 
chemically stable 
correct biopharmaceutical properties 
choice of excipients essential 

Need to ensure correct brittle-plastic balance, flow , moisture content, granule porosity, lubrication

Question 20

Mechanical strength of tablets affected by:

Answer 20

particle size, distribution, shape 
Granule porosity 
moisture content 
fragmentation and viscoelastic deformation 
applied load (compaction force) -- usually higher load will lead to stronger tablet 
time of loading 
time of unloading 
elastic stress release upon ejection

Question 21

Material requirements for tablets:

Answer 21

ideal brittle-plastic balance for good compressibility
adequate granule porosity for compressibility
sufficient moisture content for correct compressibility
good powder flow for ideal tabletability
correct level of lubrication for good compactibility

Question 22

Segregation challenges in compaction

Answer 22

Achieving good content uniformity:

• substantial risk of segregation at different steps of feeding process from hopper to feeder
• Tendency of feed to segregate increases with large differences in form, size and/or density of particles/granules

Flow must be free and uniform into die to ensure:

• tablet weight uniformity
• tablets with consistent and reproducible properties