Tablets – an interesting galenic formulation for dietary supplements

Tablets – an interesting galenic formulation for dietary supplements

 

There is no other administration form that is used as often as the tablet. Derived from the Latin word “tabuletta”, meaning “little tablet” or “little board”. The definition is: The tablet is a single dose, solid administration form, which is manufactured using mechanical pressure by pressing dried substances such as powders or granulates. The derivation of the term from Latin is seldom accurate nowadays as the majority of the compressed tablets are meanwhile cylindrical in shape. There are also many other branches of industry that today also produce tablets such as, for example, dishwasher tablets or animal feed and plant protection products. [1][2]

Advantages of a tablet

There are many things that make a strong case for the tablet to be regarded as undisputedly the most important administration form. The majority of all raw materials – some requiring corresponding pre-treatment – can be processed into tablets, the production can be automated to large degree and therefore makes production of large volumes cost-effective. The dosage can be controlled and the stability can be guaranteed for a longer period of time that is customary for the market when stored correctly. The safe and also very comfortable administration should also be regarded as an advantage. The consumer can easily carry the tablets with them and take them inconspicuously at the right time. The various sizes and the corresponding outer appearance help the consumer to differentiate the various products or also dosages from each other. The favourable shape and breakage stability contribute to allowing tablets to be easily packaged and so easy to transport as a result. [3]

The history of the tablet

The often used method of incorporating drugs in pastry foods was already practiced in Ancient Egypt around 1500 B.C. Pastilles, pills or other formed, solid shapes can be regarded as the immediate predecessors of the tablet. Just like the Egyptians before them, the ancient Greeks also prepared little balls from unpalatable active ingredients. The invention of the manual tablet press by Brockedon in 1843 brought about a change in the area of solid, peroral administration forms. The industrial-scale production of tablets was advanced in Europe in 1884 by the company Burroughs Wellcome & Co. in London. It copyrighted the term “tabloid” as a brand name and subsequently went on to produce very large numbers of tablets. [1]

Tablet production

The quote made by Robert C. White in 1920 that “the life of a tablet maker is not a happy one” is very accurate in this case because the demands associated with this technologically complex process are very significant. The production of socalled pellets will be explained in more detail in the following.

The already mixed and prepared powder mass is pressed into tablets using very high pressures. For the initial tests in order to ascertain the compressibility of a powder or a powder mixture, a hand press can be used. For the further tests that are carried out on the development scale, eccentric presses or also small rotary presses can be used. The difference between an eccentric and a rotary press in the broadest sense is that the eccentric press presses from one side and the small rotary press presses from both sides. Both technologies are based on the same fundamental principle however. A mould is filled with the mixture to be pressed into tablet form and is pressed into a tablet by two stamps. The rotary press machines are, however, far more effective than the eccentric presses because they contain a far larger number of tools (moulds, upper and lower stamps) and can produce a far larger number of tablets as a result. [1] [3]

Many active ingredients can be tabletted, many of them directly, meaning without the powder being processed any further in any way. In this case, there are so-called DC materials (DC = Direct Compression). In the majority of cases, however, in addition to the actual active ingredients, additional additives are required in order to produce technologically optimised tablets. Classed as an additive in a tablet are all those components that are not responsible for a specific dietary or physiological effect within the body. These include filling materials such as lactose, microcrystalline cellulose, starches and many more, which are required when very small volumes of the active ingredient are being processed. Croscarmellose-sodium and other modified starches are used as a disintegrant agent (decomposition agent). Magnesium stearate is used most frequently as a lubricant on the one hand to improve the flowing characteristics of the powder mixture, on the other to prevent the tablet mass from sticking to the stamps. So-called “compound additives” are additives that are produced from a mixture of various substances, for example, from microcrystalline cellulose with calcium phosphate. [1] [3]

The in-process controls that should be carried out during state-of-the-art tablet and dietary supplement production are, on the one hand, the hardness measurement, the controlling of the tablet weight, the abrasion, the tablet height and the break-down time.
 

 

Tablet shapes and types

There are wide variety of different tablet shapes. Starting with the round, bi-convex tablets, to the oval and through to the oblong variations, which are probably the most common shapes. The market also offers quadratic tablets or heart or crescent-moon shaped tablets, as well as many other shapes. The size of the tablets ranges from a 2 to 3 mm micro-tablet, through to large effervescent tablets or also glucose tablets with a diameter of 25 mm. Embossing and engraving the tablets is also possible, the design to be embossed or engraved is incorporated into the stamp and is so automatically created on the tablet during the pressing work step. These types of letterings or logos support the brand recognition and thus the product’s branding. The integration of break-lines is also possible if it is intended that it should be divisible. [4] [5]

Orally taken tablets are divided into noncoated tablets, coated tablets, tablets with altered release behaviour, enteric-coated tablets, chewable tablets, sublingual tablets (for absorption of the active ingredients via the oral mucosa) and a number of others. [4] The chewable tablet is a very practical shape. It can be taken at any time and anywhere, and without the taker requiring a glass of water. Similar with the sticks containing directly consumable powder, chewable tablets were also developed for a modern, dynamic and spontaneous life style. Large tablets can also be taken without any problems because in contrast to normal tablets, chewable tablets do not have to be taken whole. Chewable tablets are especially suited for children or elderly people who are not able or want to swallow customary tablets.

Protection of the tablets against environmental influences

Film-coated tablets are a particular type of tablet. The coating of the tablets with a film is an important processing step, among other things, as protection from environmental influences, which actually has its origins in pharmaceutical manufacturing. The demand for uncoated products in the dietary supplement market is rising constantly. Additional film coatings are applied to the tablets for stabilisation reasons because the active ingredients are often sensitive to moisture, oxygen or light. This additional protection can prevent the chemical change of the active ingredients and their possible inactivation.

A delayed release or even a entericcoated protection (also known as enteric coating) is also possible with the film coating. Furthermore, in addition to tablets, soft capsules can also be enteric coated. The requirements that the tablets to be coated need to fulfil are a low porosity, limited friability, this means limited abrasion of the tablet when subjected to mechanical stresses, and a certain tablet hardness. [6]

Refining of tablets through film-coating

A coloured film-coating of tablet cores is not only for aesthetic reasons, it is also to make the respective dietary supplement as identifiable as possible. It is possible to use natural as well as synthetic dyes. A coating also makes the tablet easier to swallow or creates a more pleasant feel in the mouth thanks to a special taste and odour masking of the ingredients. This fosters a positive attitude of the consumer towards the dietary supplement or medicine thanks to the high recognition value. This especially applies for coloured as well as flavoured film coatings, which ultimately also support the branding of the product. This results in a higher recognition value and the compliance, in other words the regular consumption of the dietary supplement, will also be positively influenced. Furthermore, filmcoated tablets are often more mechanical resistant compared with tablets without a film coating. The film coating also represents a certain barrier against product counterfeiting. [6] [7]

Legal aspects

Statutory licensing considerations may not be ignored under any circumstances when it comes to dietary supplements. This means, for example, that each country has its own ordinance which dictates which additives may be included in what amounts in a tablet. The countries often orientate themselves on the specifications of the European, American or also the Japanese pharmacopoeia. In Japan, for example, there are volume limitations for various additives such as hydroxypropyl methylcellulose (HPMC) and maize starch. [7] That means that the selected additives are classed as medicine in some countries, while as dietary supplements in others. The composition of the additives produced from microcrystalline cellulose (MCC) (E 460), colloidal silicon dioxide (E 551), sodium carboxyethyl starch and sodium stearyl fumarate are not licensed for use in dietary supplements because the latter two may only be used in medical products. Instead, croscarmellose (E 468) and mono- and diglycerides diacetyl tartaric acid from fatty acids (E 472e) are added to MCC and the colloidal silicon dioxide and are made conform for use in foods. [8] In this case only the additive E 472e has a set ADI (acceptable daily intake) value of 50 mg/kg, which needs to be complied with. All other additives do not have a set highest volume. Statutory licensing information are altered frequently, it should therefore be checked regularly with respect to its current applicability and validity. [9]

Further processing of tablets

Following their production and prior to the next processing step (film coating or packaging), the tablets are first put through a tablet deduster in order to remove technically unavoidable surface dust. It is only in this way that following further steps (e.g. coating) and the packaging can be carried out flawlessly. [10] The tablets can then be filled into blister packs or into bottles.

Outlook

A great deal of theoretical knowledge is required for tablet production. This alone is not sufficient, however, and only through a lot of practical experience can the necessary “particular feel for” be developed in order to produce technologically optimised tablets for the consumer, with the exact same quality being reproduced in each following production run. [1] In a technical centre there is the possibility to develop the optimum formulation by conducting initial compression tests on small rotary presses. The development of a dietary supplement tablet is always a challenge because the spectrum of additives that can be used in the food sector is far more limited compared with the medical sector. The producers of our various tablet additives are continuously working to improve the additives and to modify their characteristics in order that in turn, the tablets will be even better and can be even more easily produced.

 

Author

Christina Spötzl
is Product Development Manager at Goerlich Pharma GmbH. After completing her professional training as laboratory technician for dairy products, she gained her Bachelor’s degree in Food Management and Technology, focussing on healthy nutrition from the Fernhochschule Riedlingen (Online Technical University). Parallel to this, she also worked in the pharmaceutical industry for six years.

 

Literature / References:
[1] A. Bauer-Brandl, W.A. Ritschel (†): Die Tablette – Handbuch der Entwicklung, Herstellung und Qualitätssicherung (2012), Editio Cantor Verlag, Aulendorf
[2] Pharma Wiki (Medikamente und Gesundheit), http://www.pharmawiki.ch/ wiki/index.php?wiki=Tabletten (Stand: 07.02.2018)
[3] Concept Heidelberg – Seminar „Tablettierung“, 24. bis 25. Februar 2016, Heidelberg
[4] APV basics: Praktikum Tablettieren, 20. bis 21. März, KORSCH AG, Berlin
[5] U. Schöffling: Arzneiformenlehre – Ein Lehrbuch der Galenik für Theorie und Praxis (2009),Deutscher Apotheker Verlag, Stuttgart
[6] R. Voigt: Pharmazeutische Technologie (2006), Deutscher Apotheker Verlag, Stuttgart, S. 299-315
[7] Colorcon Coating School, 21. bis 23. September 2015, Colorcon GmbH, Idstein
[8] JRS Kundenseminar 16. bis 17. September 2014, JRS Pharma GmbH & Co. KG, Rosenberg
[9] A. Hahn: Nahrungsergänzungsmittel und ergänzende bilanzierte Diäten (2006), Wissenschaftliche Verlagsgesellschaft mbH Stuttgart
[10] Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Tableting (Stand: 07.02.2018)

 

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