Tablet (pharmacy)
It comprises a mixture of active substances and excipients, usually in powder form, that are pressed or compacted into a solid dose.
A polymer coating is often applied to make the tablet smoother and easier to swallow, to control the release rate of the active ingredient, to make it more resistant to the environment (extending its shelf life), or to enhance the tablet's appearance.
A tablet can be formulated to deliver an accurate dosage to a specific site in the body; it is usually taken orally, but can be administered sublingually, buccally, rectally or intravaginally.
[1] The first references to pills were found on papyruses in ancient Egypt and contained bread dough, honey, or grease.
Medicinal ingredients, such as plant powders or spices, were mixed in and formed by hand to make little balls, or pills.
Another approach, used as recently as the 19th century, was to gild them in gold and silver, although this often meant that they would pass through the digestive tract with no effect.
[1] In 1843, the British painter and inventor William Brockedon was granted a patent for a machine capable of "Shaping Pills, Lozenges, and Black Lead by Pressure in Dies".
[2] A pill was originally defined as a small, round, solid pharmaceutical oral dosage form of medication.
The word's etymology reflects the historical concepts of grinding the ingredients with a mortar and pestle and rolling the resultant paste or dough into lumps to be dried.
In the tablet-pressing process, it is important that all ingredients be fairly dry, powdered or granular, somewhat uniform in particle size, and freely flowing.
Tablet diameter and shape are determined by the machine tooling used to produce them; a die plus an upper and a lower punch are required.
Tablets need to be strong enough to resist the stresses of packaging, shipping, and handling by the pharmacist and patient.
Lubricants prevent ingredients from clumping together and from sticking to the tablet punches or capsule filling machine.
Common minerals like talc or silica, and fats, e.g. vegetable stearin, magnesium stearate or stearic acid are the most frequently used lubricants in tablets or hard gelatin capsules.
If a sufficiently homogenous mix of the components cannot be obtained with simple blending processes, the ingredients must be granulated prior to compression to assure an even distribution of the active compound in the final tablet.
The amount of liquid has to be properly controlled, as over-wetting will cause the granules to be too hard and under-wetting will cause them to be too soft and friable.
Aqueous solutions have the advantage of being safer to deal with than solvent-based systems but may not be suitable for drugs which are degraded by hydrolysis.
Hot melt extrusion is utilized in pharmaceutical solid oral dose processing to enable delivery of drugs with poor solubility and bioavailability.
Hot melt extrusion has been shown to molecularly disperse poorly soluble drugs in a polymer carrier increasing dissolution rates and bioavailability.
This usually involves low shear blending of the granules with a powdered lubricant, such as magnesium stearate or stearic acid.
Mathematically corrected punch motions can be programmed to simulate any type and model of production tablet press.
Initial quantities of active pharmaceutical ingredients are very expensive to produce, and using a Compaction Simulator reduces the amount of powder required for product development.
Mechanical systems are also incorporated for die filling, and for ejecting and removing the tablets from the press after compression.
These huge volumes require frequent in-process quality control for the tablet weight, thickness and hardness.
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.
If the rate of absorption is best in the large intestine or colon, a coating is used that is acid resistant and dissolves slowly to ensure that the tablet reaches that point before dispersing.
Automatic coaters are used for all kinds of coatings; they can be equipped with a remote control panel, a dehumidifier, and dust collectors.
