Pharmaceutical technology chemistry research projects

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Tablet Production

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Definitions:
Tablets:
•a two phase system which consist of a solid phase
(compressed powder) and the gaseous phase.
•The solid phase forms a coherent network inside the
tablet and defined form with precise outer dimensions
results.
Tablet formation:
•Transformation of the powder, a non-coherent solid
phase, into the compact tablet and this process lasts until
no further changes are induced by tableting.
Tableting:
•The process by which the compact powder is transformed
into a coherent form, the tablet.

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Tableting Process:
•The powder in the die of the tableting machine is
transformed by the influence of lower and upper punches
into a coherent form – “the tablet”
(a) Particles in the die, (b) re-orientation of particles, (c
and d) particle deformation and fracture (d) tablet in the
die.

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Different processes are responsible for cohesion of the tablet
• Particles are pushed together and re-oriented in the die until they have
arranged in the closest parking.
• This process is followed by elastic/plastic deformation of the particles
• Under the influence of applied force the particles approach each other upto
bonding
• The bonded particle collectives continue to deform
• Mechanisms of deformation and bonding is dependent on the material
properties and process conditions.
• Mechanisms of bonding are:
 Van der Waals forces
 Surface film
 Liquid or solid bridges and
 Mechanical interlocking

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TABLET MANUFACTURING PROCESS
Filling
Compression
Ejection

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Stages of Manufacturing Process
Filling
•Pre-determined amount of powder mixture is filled to the
upper edge of the die
•Filling depth is depth is determined by the height of the
die
•Filling volume is determined by diameter of the die and
filling depth.
Filling Techniques:
1.Use of moving filling shoe.
• The filling shoe moves back and forth over the die
and fills the die to the upper edge.
• The surface is levelled of by the filling shoe.

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2. Use of a stationary filling shoe
• The dies and the accessory lower punches move
below the filling shoe and the accessory upper limit
move above the filling shoe.
• The filling volume ends at the upper edge of the die
• An additional scrapper is required.
3. Use of Centrifugal Force
• Latest approach to die filling.
• The material moves through specially shaped radial
channels which approach the die from the side.
• The powder volume is determined by the positions of
the lower and upper punched in the die
• The powder at all cost be free flowing.

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Compression
•The main stage of tablet production
•The nature of compression depends on the machine
and material properties of a tablet formulation.
Stages of compression
These are once the powder has been filled into die:
•re-orientation of particles, deformation and fracture,
ending with formation of tablet in the die.

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Ejection
•Usually the lower punch moves upwards to eject the
tablet from the die and the upper will by then have left the
die when the ejection process starts.
•After ejection, the tables are collected
•Downward ejection is rare and only one type of machine
is commercially available
TYPES OF TABLETING MACHINES
•Single-punch tableting machines
•Eccentric tableting machines
•Rotary tableting machines

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SINGLE-PUNCH TABLET MACHINES
• The oldest type of tableting machines.
• The upper punch is lowered by a lever arm on the powder bed in the die
and by reciprocrating this procedure single tablets are produced.
• At typical example of a tableting machine are the hydraulically operated
machines used to produce tablets or discs for FTIR.
Lever arm
die
Tablet/powder bed

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ECCENTRIC TABLETING MACHINES
•These are also a type of a single-punch tableting
machines and are required during stages of research and
development for material development.
•Consist of a mobile upper punch and a lower punch that
remains fixed during compression.
•The lower punch moves only during ejection.
•The punch is motor driven.
a) filling, b) compression, c) ejection d) pushing from die table

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ROTARY TABLETING MACHINE
• These tableting machines are used in the
mass production of tablets.
• They work with a number of punch and die
sets which move in a circle
• The dies are fixed in a round die table and the
die table circulates
• The lower and upper punches circulates on
tracks together with dies

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TABLET COATING

17. Tablet Coating
Why is tablet coating necessary?
• Applied to improve tablet swallowability
• Mask unpleasant tastes and odor
• Protect the tablet core against water and oxygen which
can degrade the drug in the core
• Control release rate of the drug
• Brand recognition
Types of coatings
• sugar coating
• film coating
• press coating (compression coating)
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18. Sugar Coating
stages involved:
• sealing of tablet core
• subcoating
• smoothing
• colouring
• polishing
• printing
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19. Film Coating
Involves spraying a solution of polymer + pigments + plasticizers onto a
rotated, mixed tablet bed to form a thin, uniform film on tablet surface.
Components of coating material
• polymers
• solvents
• plasticizers
• colorants
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20. Film Formation
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latex particles dispersed
in aqueous phase
formation of thin film with
water evaporation through
film
continuous film

21. Air Flow
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22. Coating Process
fluid beds
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23. Important Processing Parameters
inlet and bed temperatures
relative humidity
atomization air pressure
liquid spray rate
droplet size
drying time
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24. Enteric-coated
Coating resists dissolution or disruption in stomach but not in
intestines. Used for drugs that are unstable, irritating to
stomach
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Description
Reconstitution
level
Average
weight
gain
Application ** examples
Organic Enteric
Coating system,
Cellulose Acetate
Phthalate based
5 % 8 %
Aspirin, Bisacodyl
Diclofenac Sodium
Doxylamine Succinate
Garlic Tablets, Omeprazol,
Pentaprazole,
Pentoxyfyline, Rabeprazol ,
Serrosipeptadise
Aqueous coating
system & Organic
enteric coating
system. Hydroxy
Propyl Methyl
Cellulose Phthalate
based system.
Organic: 5%
Aqueous: 10%
8 %
Methacrylic acid
copolymer type "C"
USP/NF based
system
Aqueous 20%
Hydro Alcoholic
10%
Organic System
9%

25. Press Coating
• Use of compression to form coat around a pre-formed
core.
Used mainly to separate chemically incompatible materials
• also dual release patterns possible
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Selected coating problems
a) Defective coatings: caused by poor quality of the core or inadequate
coating formulations.
b) Chipping: Solid content is too high or it too brittle for want of plasticizer
and the film does not adhere properly to the substrate surface.
c) Blistering: Drying or spraying is performed at high speed, and solvent
may be retained in the film. They evaporate on postdrying and may then
form blisters in the film.
d) Cracks in film or along Edges: Caused by too much internal stress,
owing to differences in the thermal expansion of film and core or also
caused by swelling of the core during the coating operation

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e) Embedded Particles: Particles broken off from the
core are embedded in the film during spraying.
f) Picking: The film surface contains substances that
are not molecularly dispersed and start to melt at the
core bed temperature of the film coating process.
These substances may interfere with film-forming
polymers and produce holes in the film surface.
g) Dull surfaces: The film will be dull and totally devoid
of gloss if a coating process does not produce a
requisite smooth surface. This happens if the spray
droplets start to dry befor reaching the core and are
too viscous to form a smooth film.
h) Twinning: The core permanently stick together