tablet hardness test

8/17/2019 Tablet Hardness Test

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Advantages/

DisadvantagesDefinition

BSP4A

Group 3

Applications/

Uses

Instrumen-

tation

TABLET

HARDNESS TESTPresented by:

Calingasan, Ana Theresa U.

Cortuna, Nadia Czarina Mae S.

De Guzman, Liza Marie C.


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T BLET

A solid dosage form of medicinal substances

usually prepared with the aid of suitable

pharmaceutical adjuncts

DefinitionBSP4A

Group 3

Applications/

Uses

Advantages/

Disadvantages

Instrumen-

tation


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H RDNESS

Is the measure of how resistant solid matter is

to the various kinds of permanent shape

change when a force is applied

DefinitionBSP4A

Group 3

Applications/

Uses

Advantages/

Disadvantages

Instrumen-

tation


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T BLET H RDNESS

AKA “Breaking strength/force”Defined as the pressure force required to

break a tablet in a diametric compression test

DefinitionBSP4A

Group 3

Applications/

Uses

Advantages/

Disadvantages

Instrumen-

tation


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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

Group 3Definition

Applications/

Uses

Advantages/

Disadvantages

Instrumen-

tation


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BSP4A

Group 3Definition

Applications/

Uses

Advantages/

Disadvantages

Instrumen-

tation

APPLICATIONS & USES:

-to determine the need for pressure adjustments on thetableting machine

-to check the hardness conformity

*too hard –

may not disintegrate at required period

*too soft – may not withstand handling during subsequentprocessing

-Serves as criterion by which to guide product manufacturer of

its quality control specification

--indicates the resistance power to damage its intactness andreflects the internal bonding strength of granules/powderswhich can able to hold composite structure under appliedexternal force


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-to determine the need for pressure adjustments on the tabletingmachine


*too hard – may not disintegrate at required period


-Serves as criterion by which to guide product manufacturer of its

quality control specification

--indicates the resistance power to damage its intactness and reflectsthe internal bonding strength of granules/powders which can able tohold composite structure under applied external force

BSP4A

Group 3Definition

Applications/

Uses

Instrumen-

tationAdvantages/

Disadvantages

ADVANTAGES:

1. Gives an idea about the amount of force

which can able to fracture as well as it willalso help to access compatibility of

formulation

2. Serves as guideline in handling, packagingand storage of the formulation


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BSP4A

Group 3Definition

Applications/

Uses

Instrumen-

tationAdvantages/

Disadvantages

DISADVANTAGE:

1. Unable to give idea about capping and

lamination behavior of the tablet

BSP4A

Group 3


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BSP4A

Group 3Definition

Applications/

Uses

Advantages/

Disadvantages

DISADVANTAGES:

1. Unable to give idea about capping and

lamination behavior of the tablet

Instrumen-

tation

Tablet hardness tester models:1. The Monsanto Tester

2. The Strong-Cobb Tester

3. The Pfizer Tester

4. The Erweka Tester

5. The Schleuniger Tester 6. The Pharma Test

7. The Microspan Contestar


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So what are

theseinstrumentsbeing used in

tablet hardness

testing?


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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.


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Description:

THE MONSANTO TESTER

-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


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WINTERTemplateTHE MONSANTO TESTER

- Also known as the

knur led knob .

- The rotation of the

knurled knob

causes the inner of the screw to press

against the

compression spring.

- also called as the

st i r rup

- 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


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BARREL

plunger

stirrup

Knurled knob


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WINTERTemplateProcedures/ Methodology of the use:

THE MONSANTO TESTER

1. The tablet to be tested is taken in the fingers and

held on edge between the plunger and stirrup

2. The knob is rotated, so that the plunger movesinto 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


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WINTERTemplateReminders!!!

THE MONSANTO TESTER

•The operator must 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


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ADVANTAGES: DISADVANTAGES:

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


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WINTERTemplateACCEPTABLE RANGE:THE MONSANTO TESTER

a.4 to 10 kg – ordinary compressed tablets

b.2 kg - sublingual tabletsc. 2 kg – chewable tablets

d.10 kg – buccal tablet


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THE STRONG-COBB TESTER

Description:-Introduced in 1953, under US Patent No.

2,645,936 by Robert Albrecht

-Like Stokes Monsanto, it also measures thediametrically 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.


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1 Gauge – an indicating pressure gauge calibrated inpounds per square inch, or in any other desired unitsof measurement

2 Cyl inder – mead air clamp

The strong cobb could

be operated from acompressed air supply

via a pressure

regulator and a

need le regu lator

Plunger – as thepressure increases,

plunger is forced

against the tablet

anvi l


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1

2

3

4


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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

http://en.wikipedia.org/wiki/Ad_hochttp://en.wikipedia.org/wiki/Ad_hochttp://en.wikipedia.org/wiki/Ad_hochttp://en.wikipedia.org/wiki/Ad_hoc


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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 thecompressed air supply lines

Values obtained are 1.6 times

than Stokes Monsanto

operator variability in rates of

loading and difficulties in proper



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THE PFIZER TESTER

Description:

- Patented under US Patent No.

2,975,630 around 1960

-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


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THE PFIZER TESTER

12

23

4

5

6

1 – Cylindrical

housing

2 - Jaws

3 - Anvil

4 – Piston

5 – Spring

6 – dial gauge


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THE PFIZER TESTER

2 One of the Jaw consisted of a spring-loaded plunger, connectedto 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 tabletmounted upon one of the jaws (upper)

4 Piston - The movement of piston detected and is displayedupon 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.


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THE PFIZER TESTER

5 Spring - a distance-indicating gauge calibrated in loadunits 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 beingsqueezed between said anvil and said piston.

6 Dial gauge – where the reading is displayed


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THE PFIZER TESTER


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THE PFIZER TESTER

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 openimmediately

3. The dial gauge could then be re-set by pressure on a

release button

Procedures/ Methodology of the use:

* 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


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THE PFIZER TESTER

Advantages DisadvantagesFour to seven times

faster than Monsanto or

Strong – cobb (Fairchild

and Michel)

operator variability in

rates of loading and

difficulties in proper


Portable


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THE ERWEKA TESTER

- 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 thebeam rests. The pressure is recorded through an

indicator fastened to the weight.

Description:


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THE ERWEKA TESTER

1

2

3

1 Beam – has a

linkage whichtransmits force

to the jaw

2 Sliding Mass – as the mass moves, it progressivelyincreases its effective load on the jaw until the tablet

breaks.

3 Motor – the

sliding masswhich is

driven along

by means of

this electric

motor


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THE ERWEKA TESTER


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THE ERWEKA TESTER

Advantages Disadvantages

- Reduced scatter of

measurements

- Linear sliding

mechanisms of high

quality are usually

quite expensive and

are relatively difficult to

seal against abrasive

particles.


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THE SCHLEUNIGER TESTER

-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

Description:


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12

3

4

5

67

8

1 Powerizedplatens – it

presses the

tablet against

the measuring

jaw

2 Measuring platens – opposite the tablet, movement of measuring jaw

causes the heavy mass to tilt

3 Motor – it moves thepowerized jaw towards the

measuring jaw

4 Drive cord – as the mass tilts itmoves 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 supplyin the motor.


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12

3

4

5

67

8

5 Scale – where theforce applied to the

tablet will be shown

6 Pointer – adjacent to the scale to indicatethe breaking force

7 Drag contact –as drag contact

moves to the

right, it contacts a

pointer, which

shows the forceapplied to the

tablet on a linear

scale. 8 Reset motor - the pointer is returnedto zero via reset motor


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Platens - two platens between which tablets

is placed and compressed and the value of the hardness is measured.


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- The platens should be parallel.

-Their faces should be polished smooth and precision-

ground 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.

REMINDERS!!


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-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 measurementsmay be too slow for real time monitoring of tablet

production.


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Advantages

- Reliable and more accurate


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Summary

Apparatus MechanismStokes-Monsanto Spring

Strong-Cobb Air pump

Pfizer Hard pliers

Erweka Suspended weight

Schleuniger Platens


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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 thanswinging 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 anabsolute accuracy of ± 1%.

5. The moving jaw travels at a relatively fast, fixed, feed

rate


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THE PHARMA TEST

THE PHARMA TEST HARDNESS TESTER


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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


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THE MICROSPAN CONTESTAR


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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


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There is no such o ff ic ial specif icat ion

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.


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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, wefirst check its disintegration before rejecting the

batch . And if the disintegration is within limit,

we accept the batch.


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END

tablet hardness test

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