Tablet Hardness Test

BSP4A Group 3

Definition

Applications/ Uses

Advantages/ Disadvantages

Instrumentation

TABLET HARDNESS TEST Presented by: Calingasan, Ana Theresa U. Cortuna, Nadia Czarina Mae S. De Guzman, Liza Marie C.

BSP4A Group 3

Definition

Applications/ Uses


Instrumentation

TABLET A solid dosage form of medicinal substances usually prepared with the aid of suitable pharmaceutical adjuncts

BSP4A Group 3

Definition

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Instrumentation

HARDNESS Is the measure of how resistant solid matter is to the various kinds of permanent shape change when a force is applied

BSP4A Group 3

Definition

Applications/ Uses


Instrumentation

TABLET HARDNESS AKA “Breaking strength/force” Defined as the pressure force required to break a tablet in a diametric compression test

BSP4A Group 3

Definition

Applications/ Uses


Instrumentation

Tablet Hardness Test is important for the evaluation of the following properties of tablets: a) Ability to withstand the shock of handling, packaging and shipping b)An important physical parameter in the control of tablets c) Shown to be related to solubility

BSP4A

Definition

Group 3

Applications/ Uses


Instrumentation

APPLICATIONS & USES: -to determine the need for pressure adjustments on the

tableting machine

-to check the hardness conformity

*too hard – may not disintegrate at required period *too soft – may not withstand handling during subsequent processing -Serves as criterion by which to guide product manufacturer of its quality control specification --indicates the resistance power to damage its intactness and reflects the internal bonding strength of granules/powders which can able to hold composite structure under applied external force

BSP4A Group 3

Definition

Applications/ Uses


Instrumentation

ADVANTAGES: -to determine the need for pressure adjustments on the tableting APPLICATIONS & USES: machine

1. Gives an idea about the amount of force -to check the hardness conformity which can able to fracture as well as it will *too hard – may not disintegrate at required period also help to access compatibility of *too soft – may not withstand handling during subsequent formulation processing -Serves as criterion by which to guide product manufacturer of its 2. Serves guideline in handling, packaging quality controlas specification

and storage ofpower the toformulation --indicates the resistance damage its intactness and reflects the internal bonding strength of granules/powders which can able to hold composite structure under applied external force

BSP4A

Definition

Group 3

Applications/ Uses


Instrumentation

APPLICATIONS & USES: -to determine the need for pressure adjustments on the tableting machine

DISADVANTAGE: -to check the hardness conformity

hard – may disintegrate requiredcapping period 1. *too Unable tonot give idea atabout and *too soft – may not behavior withstand handling during subsequent lamination of the tablet processing

-Serves as criterion by which to guide product manufacturer of its quality control specification --indicates the resistance power to damage its intactness and reflects the internal bonding strength of granules/powders which can able to hold composite structure under applied external force

BSP4A Group 3

Definition

Applications/ Uses


Instrumentation

TabletDISADVANTAGES: hardness tester models: -to determine the need for pressure adjustments on the tableting APPLICATIONS & USES:

1. The Monsanto Tester machine

1. Unable to give idea about capping and -to check the hardness conformity 2. The Strong-Cobb Tester lamination behavior of the tablet *too hard – may not disintegrate at required period

3. The Pfizer Tester

*too soft – may not withstand handling during subsequent 4. Theprocessing Erweka Tester -Serves as criterion by which to guide product manufacturer of its 5. The Schleuniger Tester quality control specification --indicates the resistance 6. The Pharma Testpower to damage its intactness and reflects the internal bonding strength of granules/powders which can able to hold The composite structureContestar under applied external force 7. Microspan

So what are these instruments being used in tablet hardness testing?

Rule of Thumb - Most primitive way and practical test for hardness of tablets -rule of thumb described a tablet to be of proper hardness if it was firm enough to break with a sharp snap when it was held between the 2nd and 3rd fingers using thumb as fulcrum, yet didn’t break when it fell on the floor.

THE MONSANTO TESTER Description: -It is manufactured and introduced by Monsanto in 1936. It is the first tablet hardness tester made available in the market -It is a hand operated device in the form of a plated metal cylinder, about 150 mm in length and 25 mm in diameter -Also known as the Stokes Hardness tester -it measures the force required to break the tablet when the force generated by a coil spring is applied diametrally to the tablet

THE MONSANTO TESTER

WINTER Template

- Also known as the knurled knob. - The rotation of the knurled knob causes the inner of the screw to press against the compression spring.

- also called as the stirrup - It is a support at the far end of the device when the tablet is compressed

-also

called as the plunger - adapted to engage the tablet

THE MONSANTO TESTER

WINTER

BARREL Template

plunger

stirrup

Knurled knob

THE MONSANTO TESTER

WINTER Template

THE MONSANTO TESTER

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Procedures/ Methodology of the use: 1. The tablet to be tested is taken in the fingers and Template held on edge between the plunger and stirrup

2. The knob is rotated, so that the plunger moves into light contact with the tablet, and the sliding scale is moved to zero position 3. Further rotation of the knurled knob increases the spring tension, until the tablet eventually breaks, by the tensile failure across its diameter 4. The new scale is recorded

THE MONSANTO TESTER Reminders!!!

WINTER

•The operator must Template always ensure that the tablet is inserted in such a way that compression takes place across a diameter: it must not be set an angle •The load must be applied at a steady, reproducible rate •The spring must be correctly calibrated for its scale, and must not exhibit fatigue •The jaws must be kept clean, while the plunger must be free to travel in its housing without undue friction •The zero must be correctly re-set for each new size of table to be tested

THE MONSANTO TESTER ADVANTAGES:

WINTER DISADVANTAGES:

Template

Low priced

Hardness obtained is lesser by 1.5% - 7.5% compared to later development

Convenient

Instrument uses spring which has no standard of compression

Small and portable

If many tablets are to be measured, the procedure is seen as tedious operator variability in rates of loading and difficulties in proper setup and calibration

THE MONSANTO TESTER

WINTER

ACCEPTABLE RANGE:

Template

a. 4 to 10 kg – ordinary compressed tablets b. 2 kg - sublingual tablets c. 2 kg – chewable tablets d. 10 kg – buccal tablet

THE STRONG-COBB TESTER Description: -Introduced in 1953, under US Patent No. 2,645,936 by Robert Albrecht -Like Stokes Monsanto, it also measures the diametrically applied force required to break a tablet. - It measures the applied force (in Kg) required to break a tablet across its diameter. The force is produced by a manually or pressure-operated pump.

THE STRONG-COBB TESTER 1 Gauge – an indicating pressure gauge calibrated in pounds per square inch, or in any other desired units of measurement

Plunger – as the pressure increases, plunger is forced against the tablet

The strong cobb could be operated from a compressed air supply via a pressure regulator and a needle regulator

2 Cylinder – mead air clamp anvil

THE STRONG-COBB TESTER 1 3 2

4

THE STRONG-COBB TESTER Strong-Cobb Unit - An ad hoc unit of force which is a legacy of one the first tablet hardness testing machines. -Although the Strong-Cobb unit is arbitrarily based on the dial reading of a hardness tester, it became an international standard for tablet hardness in the 1950s until it was superseded by testers using SI units in the 1980s. - The Strong-Cobb is a unit with a very unusual name for a unit of measurement since it is named after the company, Strong-Cobb Inc. Conversion:

1.4 SC = 1 Kg

THE STRONG-COBB TESTER ADVANTAGES:

DISADVANTAGES:

Did not depend on the mechanical properties of a metal spring, and therefore did not suffer from metal fatigue through prolonged use

Air pump get damages. The cylinder is very susceptible to the effects of dusts and grits. The needle valve can be affected by materials deposited from the compressed air supply lines

Values obtained are 1.6 times operator variability in rates of than Stokes Monsanto loading and difficulties in proper setup and calibration

THE PFIZER TESTER Description:

- Patented under US 2,975,630 around 1960

Patent

No.

-Pfizers produced this new portable tester which was, in principle, like of pliers - The tablet is crushed in between the jaws of the device. The force is indicated on the dial indicator

THE PFIZER TESTER 1 – Cylindrical housing 2 - Jaws 3 - Anvil 4 – Piston 5 – Spring 6 – dial gauge

6

1 3

2 2 5

4

THE PFIZER TESTER 2 One of the Jaw consisted of a spring-loaded plunger, connected to a dial gauge with a ratchet to retain the maximum reading the other jaw swiveled, and was adjustable to suit tablet of various diameters

3 Anvil – a pivoted anvil

for supporting a tablet mounted upon one of the jaws (upper)

4

Piston - The movement of piston detected and is displayed upon the face of gauge which is accurately calibrated to dependably indicate imposed force on gauging spring over its entire range instant the tablet is crushed.

THE PFIZER TESTER 5

Spring - a distance-indicating gauge calibrated in load units having a sensing finger mounted upon the housing, and the sensing finger passing through the housing into contact with piston to permit the gauge to provide a continuous indication of the load applied to a tablet being squeezed between said anvil and said piston.

6 Dial gauge – where the reading is displayed

THE PFIZER TESTER

THE PFIZER TESTER Procedures/ Methodology of the use: 1. Tablet is inserted squarely between the jaws, and the plier handles were squeezed steadily until the breakage point 2. On the release of hand pressure, the jaws open immediately 3. The dial gauge could then be re-set by pressure on a release button * A limit stop prevented the two jaws from damage by impact, since otherwise the stored energy in the spring could have driven the two together as the tablet shattered

THE PFIZER TESTER Advantages Four to seven times faster than Monsanto or Strong – cobb (Fairchild and Michel) Portable

Disadvantages operator variability in rates of loading and difficulties in proper setup and calibration

THE ERWEKA TESTER Description: - Uses the principle of a steelyard balance to load a vertically sliding jaw by means of a weighted beam. -a beam fastened to one end to a pivot applies the breaking force. A motor moves a weight along the beam at constant speed, and increase the force against the tail, in which the other end of the beam rests. The pressure is recorded through an indicator fastened to the weight.

THE ERWEKA TESTER 1 Beam – has a linkage which transmits force to the jaw

3 1

2

3 Motor – the sliding mass which is driven along by means of this electric motor

2 Sliding Mass – as the mass moves, it progressively increases its effective load on the jaw until the tablet breaks.

THE ERWEKA TESTER

THE ERWEKA TESTER Advantages - Reduced scatter measurements

Disadvantages of Linear sliding mechanisms of high quality are usually quite expensive and are relatively difficult to seal against abrasive particles.

THE SCHLEUNIGER TESTER Description: -Also known as “Heberlein Model” -Most widely used instrument for tablet hardness test -The earliest version of this instrument had no motor drive, but were operated by means of a handwheel; the motor was soon added, and by 1969 both versions were to be seen. -This instrument uses an ingenious arrangement of levers to provide a normally constant rate of loading for a constant speed of jaw travel

THE SCHLEUNIGER TESTER 2

Measuring platens– opposite the tablet, movement of measuring jaw causes the heavy mass to tilt 8 5

1

Powerized platens – it presses the tablet against the measuring jaw

7

6 2

1

4

3

3 Motor – it moves the powerized jaw towards the measuring jaw

Drive cord – as the mass tilts it moves the drive cord which then carries an electrical contact across a horizontal scale; that contact presses, in turn, against a second frictionally set contact which maintains power supply in the motor.

4

THE SCHLEUNIGER TESTER 6 Pointer – adjacent to the scale to indicate

5 Scale – where the

the breaking force

force applied to the tablet will be shown 8 5 7

7 Drag contact – as drag contact moves to the right, it contacts a pointer, which shows the force applied to the tablet on a linear scale.

6 2

1

4

3

8 Reset motor - the pointer is returned to zero via reset motor

THE SCHLEUNIGER TESTER

Platens - two platens between which tablets is placed and compressed and the value of the hardness is measured.

THE SCHLEUNIGER TESTER REMINDERS!! - The platens should be parallel. -Their faces should be polished smooth and precisionground perpendicularly to the direction of movement.

- Perpendicularity must be preserved during platen movement, and the mechanism should be free of any bending or torsion displacements as the load is applied. -The contact faces must be larger than the area of contact with the tablet.

THE SCHLEUNIGER TESTER -Either the rate of platen movement or the rate at which the compressive force is applied (i.e., the loading rate) should be constant. Maintaining a constant loading rate avoids the rapid buildup of compressive loads, which may lead to uncontrolled crushing or shear failure and greater variability in the measured breaking force. *However, constant loading rate measurements may be too slow for real time monitoring of tablet production.



Advantages

- Reliable and more accurate

Summary Apparatus Stokes-Monsanto Strong-Cobb Pfizer Erweka Schleuniger

Mechanism Spring Air pump Hard pliers Suspended weight Platens

THE PHARMA TEST -Pharma Tests are apparatus manufacturers from West Germany.

Features of Pharma Test Hardness Tester:

1. Has a horizontally moving jaw, rather on the lines of those used by the Schleuniger instrument 2. The rate of loading is controlled electronically, rather than swinging mass 3. There is an automatic feeder, which can draw a continuous procession of tablets from a hopper and can present them, one at a time. 4. The machines claimed resolution of 0.1 kg and an absolute accuracy of ± 1%. 5. The moving jaw travels at a relatively fast, fixed, feed rate

THE PHARMA TEST THE PHARMA TEST HARDNESS TESTER

THE MICROSPAN CONTESTAR Features:

-It has been designed with the object of providing measurement not only of tablet hardness, but also thickness and weight. -This machines is unique that it can accepted mixed batches of tablets of different shapes and sizes, automatically moving them to stations for the successive measurement of thickness, weight and hardness -It incorporates a microprocessor and can print out statistical analysis of its accumulated readings

THE MICROSPAN CONTESTAR

ADDITIONAL INFORMATION: Factors affecting strength (hardness) of tablets: -Speed

of compression -Solid state structure -Particle Size -Solid bridges -Mechanical Interlocking -distance force -Bonding Mechanisms -Volume reduction mechanisms of powder -Surface Area change

There is no such official specification given in any pharmacopoeia about hardness of material and hardness test. Formulator should have to decide and maintain the range of hardness during preparation based upon requirement as well as type of formulation. e.g. effervescent or mouth dissolving tablet should have low hardness as compared to conventional immediate release tablet or enteric coated tablet.

REMINDERS!!! Hardness can affect the disintegration. So if the tablet is too hard, it may not disintegrate in the required period of time. And if the tablet is too soft, it will not withstand the handling during subsequent processing such as coating or packaging. In general, if the tablet hardness is too high, we first check its disintegration before rejecting the batch . And if the disintegration is within limit, we accept the batch.

END

Tablet Hardness Test

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