Transcript Tablet manufacture

Tabletting formulations
 In the tablet-pressing process, it is important that all ingredients be
fairly dry, powdered or granular, somewhat uniform in particle size and
freely flowing.
 Mixed particle sized powder can segregate during manufacturing
operations, which can result in tablets with poor drug or active
pharmaceutical ingredient (API) content uniformity.
Content uniformity ensures that the same API dose is delivered with
each tablet.
 Most tablet formulations include excipients.
Binder is added in the formulation to help hold the tablet together and
give it strength e.g. lactose and hydroxyproylmethylcellulose.
 Often, an ingredient is also needed to act as a
disintegrant to aid tablet dispersion once swallowed
releasing the API for absorption.
 Some amounts of lubricants are usually added as well.
The most common of these is magnesium stearate. These
help the tablets once pressed to be more easily ejected from
the die.
Tablet production
Powders intended for compression into tablets must possess two
essential properties:
Powder fluidity
The material can be transported through the hopper into the
die.
To produce tablets of a consistent weight.
Powder flow can be improved mechanically by the use of
vibrators, incorporate the glidant.
Powder compressibility
The property of forming a stable intact mass when pressure is
applied.
Important technical properties of powders must be
controlled to ensure success of tableting operation such as,
- homogeneity,
- good flowability,
- good compressibility,
- cohesiveness,
- avoidance of sticking to the die surface or punch tips.
Since most materials have none or some of these properties,
methods of tablet formulation (addition of tablet excipients)
and preparation (three methods; wet granulation, dry
granulation and direct compression) have been developed to impart
the materials to be compressed these characteristics.
Compressed tablets
Tablets diameters and shapes are determined by the die and punches used for the
compression of the tablet. The thickness of a tablets are determined by the amount
of fill permitted to enter the die and the amount of pressure applied during
compression .
The tablets is formed by the pressure exerted on the granulation by the punches
within the die cavity. While round tablets are more generally used, shapes such as
oval, capsule-form, square, triangular may be used. The curvature of the faces of the
punches determines the curvature of the tablets.
Punch faces with ridges are used for compressed tablets scored for breaking into
halves or fourths. Tablets engraved or embossed with symbols, require punches with
faces embossed or engraved with the corresponding designs.
The use of the tablet sometimes determines its shape, effervescent tablets are
usually large, round, flat, while vitamin tablets are frequently prepared in capsuleshaped forms.
Tableting is a compaction process and
Involves two steps:
Compression
►Reduction in bulk volume by eliminating voids and
bringing particles into closer contact.
Consolidation
►Increased mechanical strength due to interparticulate
interactions.
Tablet manufacturing
Tablets are prepared by forcing particles (drug and excipients) into a closed
compartment (die cavity) followed by (powder or granules) compression (by
punches), to allow the particles to cohere into a porous solid mass (tablet).
Tablet machines
Hopper
Machines built to compress tablets consist of:
1- Hopper: for holding granulations for compressing.
2- Feed frame: for distributing the materials into the dies.
3- Dies: for controlling the size and the shape of the tablet.
4- Punches: for compressing the granulations within the dies.
5- Cam tracks for guiding the movement of the punches.
Tablet machines cont.
Upper punch
Die cavity
Die
Dies: for controlling the size and the shape of the
tablet
Stages in tablet formation
"Compaction cycle“
1- Die filling.
2- Tablet formation.
3- Tablet ejection.
1- Die filling:
Flow of powders (or granules) of the drug and excipients from a
hopper into the die. N.B. the die is closed at its lower end by the lower
punch.
2- Tablet formation:
The upper punch descends powder and enters the die and the powder
is compressed until a tablet is formed. N.B. lower punch may be
stationary or moving upward in the die. After maximum applied force
is reached, the upper punch leaves the die by moving upward.
3- Tablet ejection:
The lower punch rises up until its tip reaches the die top.
The tablet is subsequently removed by a pushing device.
Stages of tablet formation
Types of Tablet press
They differ in their rate of production:
1- Single-punch press: It is composed of one die and one
pair of punches (up to 100 tab/ min).
2- Rotary tablet press: It contains ≥60 dies (10,000
tablets/min). It is used for large scale production.
3- Hydraulic press: For research work (computerized).
Single punch machine:
 The compression is applied by the upper punch
 Stamping press
Single punch machine
The weight of the tablet is determined by the volume of the die cavity, the lower punch is
adjustable to increase or decrease the volume of granulation, thus increasing or decreasing the
weight of tablet.
Single Punch Machine (Tablets)
Upper and
Lower Collar
Collar locker
The compression cycle of single-punch tablet press
Rotary tablet machines
Multi-station rotary presses
For increased production the rotary machines offer the greatest advantages.
 The head of the tablet machine that holds the upper punches, dies and lower
punches in place rotates. A head carrying a number of sets of punches and dies
revolves continuously while the tablet granulation runs from the hopper into the dies
placed in a large, steel plate revolving under it. This method promotes a uniform fill of
the die and therefore an accurate weight for the tablet.
 As the head rotates, the punches are guided up and down by fixed cam tracks,
which control the sequence of filling, compression and ejection.
 The portions of the head that hold the upper and lower punches are called the upper
an lower turrets.
The portion holding the dies is called the die table
The pull down cam (C) guides the lower punches to the
bottom, allowing the dies to overfill.
 The punches then pass over a weight-control cam (E),
which reduces the fill in the dies to the desired amount.
 A swipe off blade (D) at the end of the feed frame
removes the excess granulation and directs it around the
turret and back into the front of the feed frame.
 The lower punches travel over the lower compression
roll (F) while simultaneously the upper punches ride
beneath the upper compression roll (G).
 The upper punches enter a fixed distance into the dies,
while the lower punches are raised to squeeze and compact
the granulation within the dies.
 After the moment of compression, the upper punches
are withdrawn as they follow the upper punch raising cam
(H).
 The lower punches ride up the cam (I) which brings the
tablets flush with or slightly above the surface of the dies.
 The tablets strike a sweep off blade affixed to the front
of the feed frame (A) and slide down a chute into a
receptacle.
 At the same time, the lower punches re-enter the pull
down cam (C) and the cycle is repeated.
Rotary Press Machine
Rotary tablet press
Although tablet compressing machinery has undergone
numerous mechanical modifications over the years, the
compaction of materials between a pair of moving punches
within a stationary die has remained unchanged
The principle modification from earlier equipment has been
an increase in production rate which is regulated by
Number of tooling sets
Number of compression stations
Rotational speed of the press
 Special adaptations of tablet machines allow for the
compression of layered tablets and coated tablets.
Multilayer rotary tablet machine.
Tablet Ingredients (excipients)