Tablet

For other meanings please see Tablet (disambiguation)

Common disk-shaped tablets

A tablet is a mixture of active substances and binders, usually in powder form, pressed into a solid.

Medicines to be taken orally are very often supplied in tablet form; indeed the word tablet without qualification would be taken to refer to a medicinal tablet. Medicinal tablets are usually called pills. Other products are manufactured in the form of tablets which dissolve; e.g., for cleaning and deodorizing.

Medicinal tablets are usually intended to be swallowed, and are of a suitable size and shape. A coating may be applied to hide the taste of the tablet's components. Tablets for other purposes, e.g., effervescent medicinal tablets and non-medicinal tablets, may be larger.

Medicinal tablets were originally made in the shape of a disk of whatever colour their components determined, but are now made in many shapes and colours to help users to distinguish between different medicines that they take. Tablets are often stamped with symbols, letters, and numbers which enable them to be identified. Sizes of tablets to be swallowed range from a few millimeters to about a centimeter. Some tablets are in the shape of capsules, and are called "caplets".

Tablets are often scored to allow them easily to be broken into equal halves for smaller doses.

Some people have difficulty swallowing tablets, this is called dysphagia. This is often caused by a gag reflex.

Contents

1 Tabletting formulations
2 Tablet coating
3 Tablet presses
4
5 See also
6 External links

Tabletting formulations

In the tablet-pressing process, it is important that all ingredients be dry, powdered, and of uniform grain size as much as possible. Mixed grain sizes tend to separate out due to operational vibrations, resulting in inconsistent tableting, while any moisture in the system will tend to clog the tableting pathways.

Some substances may be tableted as pure substances, but this is usually not the case; most formulations include excipients. Normally, an inactive ingredient termed a binder is added to help hold the tablet together and give it strength. A wide variety of binders may be used, some common ones including lactose powder, sucrose powder, tapioca starch (cassava flour) and microcrystalline cellulose.

Often, an ingredient is also needed to act as an Disintegrant. This is an ingredient that dissolves readily in water to help the tablet disperse once swallowed. Some binders, such as starch, are also excellent disintegrants.

Small amounts of lubricants are usually added, as well. The most common of these are stearic acid (stearin) and magnesium stearate. These help the tablets, once pressed, to be more easily ejected from the die.

Various pills

Tablet coating

Many tablets today are coated after being pressed. Although sugar-coating was popular in the past, the process has many drawbacks. Modern tablet coatings are polymer and polysaccharide based, with plasticizers and pigments included. Tablet coatings must be stable and strong enough to survive the handling of the tablet, must not make tablets stick together during the coating process, and must follow the fine contours of embossed characters or logos on tablets. Coatings can also facilitate printing on tablets, if required. Coatings are necessary for tablets that have an unpleasant taste, and a smoother finish makes large tablets easier to swallow. Tablet coatings are also useful to extend the shelf-life of components that are sensitive to moisture or oxidation. Opaque materials like titanium dioxide can protect light-sensitive actives from photodegradation. Special coatings (for example with pearlescent effects) can enhance brand recognition.

If the active ingredient of a tablet is sensitive to acid, or is irritant to the stomach lining, an enteric coating can be used, which is resistant to stomach acid and dissolves in the high pH of the intestines. Enteric coatings are also used for medicines that can be negatively affected by taking a long time to reach the small intestine where they are absorbed.

Tablet presses

Tablet presses, the machines that make the tablets, range from small, inexpensive bench-top models that make one tablet at a time, no more than a few thousand an hour, and with only around a half-ton pressure, to large, computerized, industrial models that can make hundreds of thousands of tablets an hour with much greater pressure. Some tablet presses can make extremely large tablets, such as some of the toilet cleaning and deodorizing products or dishwasher soap. Others can make smaller tablets, from your regular asperin to some the size of a bb. Tablet presses may also be used to form tablets out of a wide variety of materials, from powdered metals to cookie crumbs. Currently the tablet press an important piece of machinery for any manufacturer who wishes to get into pharmaceutical manufacturing.

[Advance Eng.]

It is sometimes necessary to split pills into halves or quarters. Tablets are easier to break accurately if scored, but there are devices which cut unscored pills.

External links

[Colorcon], tablet coatings and excipients.
[Advance Eng.], Tablet presses and other pharmaceutical machinery.