IPT_18_pg74-76_2005

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Tablets are probably the most successful form of

administering medicines, and also offer an efficient

means of reducing powders and granules into a

compact product. The tablet is versatile, compact,

robust, accurate and can be mass-produced consistently

at high speeds. It is an incredibly versatile drug delivery

device – its limitations being defined only by the

imagination of the tablet designer.

The design of a tablet is extremely important from many

aspects, and it is wise to involve the tablet-tooling supplierfrom the onset. Good design can avoid many of the

common tabletting pitfalls – such as sticking, picking,

laminating and capping. It can also ensure optimum

productivity, avoiding premature tooling wear and – in the

worst case – tooling failure. Tapping into the vast experience

of the tooling manufacturer is the surest way of obtaining

advice on the best options for a unique and problem-free

tablet. As well as tooling strength,

durability and tablet functionality,

tablet design also has an integral

relationship with the marketing

and advertising strategy for a

product. It influences product

identity for the dispenser,

patient/consumer brand loyalty,

the packaging process and the

effectiveness of film- or sugar-coating

of tablets.

The tablet tooling supplier should

have a major influence on the

versatility and potential of the

design and application of a tablet – right from the initial

design stage. Utilisation of their experience, and

understanding of the industry and its products, should

be viewed as an extra resource for a company’s business.

The formulation of powders into a tablet has

applications across many industry sectors:

Pharmaceuticals – ethical drugs, generics,

homeopathic therapies, and prescription

and over the counter (OTC) medicines Nutraceuticals – vitamins, minerals,

health supplements

Confectionery – sweets, mints, breath fresheners,

lozenges, chocolates

Household – textile and dishwashing tablets,

sterilising tablets

Chemicals – catalysts, chemicals, cleaning agents,

salt, chlorine

Industrial – air bag pellets, battery cells, ceramics,

sintered products, paints

Military/pyrotechnics/fuel – gun-powder tablets,

fireworks, nuclear fuel pellets

Cosmetics – powder compacts, make-up

Veterinary – animal medicines and health care

THE TABLETTING PROCESS

Tablet-making is an established and sophisticated

process using bespoke state-of-the-art equipment and

procedures. Tablets can be produced, processed and

packaged in very high volumes at very high speeds;

the process is highly controlled, compact, versatile,

Drug Delivery

74 Innovations in Pharmaceutical Technology

Tablet Design: A CriticalAspect of Product DevelopmentGood tablet design can provide a manufacturer with a unique product –but it can also help to ensure optimum productivity, avoiding prematuretooling wear and failure.

By Trevor Higgins at I Holland Limited

Trevor Higgins is the Research and Engineering Director of I Holland Limited (Nottingham, England). He joined the company

in 1969 and, as the first company apprentice, developed unique ‘hands-on’ experience in the manufacture of tablet toolingand associated key issues. Mr Higgins has been the driving force behind many technical innovations at I Holland, includingthe introduction of technical solutions for the global tablet tooling industry, such as the rotating head for standard B and D

type punches, and the universal seal groove for seals, bellows and drip cups. He is the author of ‘Eurostandard’, Europe’sleading standard for interchangeable punches and dies for European-built tablet presses; he is also on the TSM (Tableting

Specification Manual) steering committee and has contributed to the new ISO 18084 draft standard for punches and dies.

Figure 1: A sample

of the rotating head

for Euro B and D

type punches

This has been

designed to ensure

that wear on the

punch-head is evenly

distributed over the

tablet production

cycle, helping to

extend the life of

the punch.

8/14/2019 IPT_18_pg74-76_2005


75Innovations in Pharmaceutical Technology

the aesthetics, this can be used functionally to aid

packaging, to orientate the tablet for printing processes

or to tilt the tablet to enable people with arthritic

fingers to grasp the tablet with ease. Incorporating a

score on the tablet face enables the tablet to be broken

into smaller controlled dosages – one score to bisect the

tablet or cross-scores to break the tablet into four. Even

special scores can be applied where the tablet can be

broken simply by pressing with a finger or thumb, this

is most appropriate for smaller tablets. The profile

of a tablet is important to assist the film- or sugar-coating process, or even to help with the swallowing

of the tablet; it can be modified to increase or decrease

the surface area of the tablet, which may be important

for dissolution rates or controlled release of the

tablet ingredients.

Again, a good tooling supplier will have a CAD/CAM

facility and be able to advise on the optimum profile.

The supplier would also need to consider the strength

and durability of the tooling; by using Finite Element

Analysis (FEA) software, maximum static loadings and

fatigue performance can be predicted (Figure 3, see page

76). From this, modifications to the profile can be

determined in order to deliver the safest profile and best

tooling durability.

Colour

The opportunities for tablet colouring and colour

combinations are endless, especially with modern film

coatings. Also, bi-layer and tri-layer tablets can have

combinations of colours. Colours are extremely

important for marketing, brand identity, dosages,

robust and accurate. Whilst the principles for tablet

compression have not changed for over 60 years, the

process and equipment are developed to extremely

high standards. Modern tablet presses are capable of

producing more than one million tablets per hour, with

a weight variation of less than one per cent. For this to bepossible, the tablet tooling must be of the highest quality

and finish, and to the optimum design.

The quality, design and maintenance of the tooling

reflects exactly the quality of the final tablet produced;

it should therefore be treated not just as a consumable

item, but as an important investment in the quality

of a product. The selection of high quality, high

performance materials and working to very fine

tolerances and finishes are only part of the story. It is

also important to understand the purpose of the tablet,

to be innovative and creative in its design and to ensure

that the tooling will produce tablets consistently and

accurately time after time. Good ongoing maintenance,

measuring and monitoring, and safe and secure

storage will prolong the life of the tooling and ensure

cost-effectiveness.

THE VERSATILITY OF TABLET DESIGN

Tablet Shape

The shape of a tablet is restricted only by the

imagination of the designer. Apart from the morepopular round or caplet shapes, all other standard

geometric shapes can be used such as oval, elliptical,

square, diamond, rectangular, polygons and so on. Also,

special shapes can be employed to add to the product’s

brand identity – such as animal shapes, fruit shapes or

even shapes representative of the ailment, such as heart-

shaped for cardiovascular medicines. Figure 2 shows the

design of a dinosaur punch developed for children’s

vitamin tablets. The shape can also be very important

for functional reasons such as alignment for tablet

printing, packaging or even for ease of swallowing by

the consumer.

By using modern CAD/CAM systems, both 2-D

drawings and 3-D models can be produced quickly and

accurately by a tooling supplier for approval by

marketing and manufacturing departments prior to the

costly stage of manufacturing prototypes.

Tablet Profile

The profile of a tablet provides an opportunity to add

to the design – giving it a third dimension. Apart from

Figure 2: Detailed

design potential

demonstrated by

the Dinosaur Punch

developed for

vitamin tablets

8/14/2019 IPT_18_pg74-76_2005


strengths and patient/consumer recognition; a good

example of the use of colour is a certain well-known

‘blue’ erectile dysfunction tablet. 3-D CAD modelling

can usually employ a vast range of colours for the tablet

design process.

Texture

Textured or nodular surfaces and different finish effects

(such as gloss, matt or pearlescence) can be employed by

the use of coatings. Texture can be designed into the

punch tip face by the tooling supplier – for example, an

orange peel effect or an extremely high gloss finish,

which can have a beneficial effect avoiding adhesion of the product to the tablet punch face.

Taste

Many drugs have a naturally bitter taste; this can be

masked by the use of flavoured or sweetened coatings, or

taste-masking additives in the tablet formulation. In

some products, the action of dissolution in the mouth

can add to the taste sensation.

Aroma

Strongly unpleasant smelling dosages can be masked

using neutral or scented coatings. Aroma can also aid

product identification, along with tablet colour, shape

and imaging options.

Imaging

Imaging can be achieved by

tabletting with embossed punches,

or by printing onto the coated

surface. These processes afford

endless opportunities for tablet

distinction and identity, including

logos, coding and functional embossing such as bisect

lines. Images or pictures, machine-readable codes or

anti-counterfeiting marks can also be applied, a very

topical issue for the industry. Applying embossing to

tablet punches is a very specialised area, and much

thought and experience should be applied to ensure theoptimum performance. The supplier will advise on the

best character and font styles and sizes to avoid

tabletting problems such as picking, capping and

laminating, or coating problems such as bridging, in-

filling or core erosion. Also, the embossing may have an

impact on the strength and durability of the tooling; the

incorrect application of embossing can seriously weaken

the tablet tooling.

Packaging

The tablet lends itself to efficient and innovative

packaging; dispensing methods include blister

packing, single tablet dispensing devices, date/day

organisers or encapsulated tablets. Some examples

include date/day organisers for oral contraceptives

or other time-critical administration. Again, it is

at the early stages of tablet design that attention needs

to be paid to packaging issues, and where the

experience of the tooling manufacturer can make a

valuable contribution.

CONCLUSION

As demonstrated by this far from exhaustive list of

features, the tablet presents many opportunities for a

unique and interesting identity and design. This –

added to the efficiency and effectiveness of the

ingredients – explains why the tablet is the most

popular form of medication. The tooling is the last

critical interface with the tablet, and is therefore a

vital part of the process. Good tooling manufacturers

have many years’ experience, and the systems and

infrastructure to provide a vital service. They can

also lend ongoing support in the area of tablet

design and problem-solving, and should have the

capability to offer innovative ideas, and provide

good CAD/CAM facilities for producing various

design options and prototypes. By providing advice

on materials, treatments and coatings, they can

enhance the performance of the tooling – resulting in

the most aesthetic, innovative, trouble-free and

effective tablets.

The author can be contacted at

[email protected]

76 Innovations in Pharmaceutical Technology

Figure 4: The

possibilities for

tablet design

are endless

Figure 3: Tablet

profile optimisation

through the use of

sophisticated Finite

Element Analysis

(FEA) techniques

Stress von Mises

N/(mm^2)

1,800

1,551.573

1,303.146

1,054.719

806.2914

557.8642

309.437

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IPT_18_pg74-76_2005