A tablet (also known as a pill) is
a pharmaceutical oral
dosage form (oral solid dosage, or OSD)
or solid unit dosage form. Tablets may be
defined as the solid unit dosage form of
medication with suitable excipients.
It comprises a mixture of active substances and
excipients, usually in powder form,
that are pressed or compacted into a solid dose.
The main advantages of tablets are that they
ensure a consistent dose of medicine that is
easy to consume.
Tablets are prepared either by moulding or by compression.
The excipients can include diluents, binders or
granulating agents, glidants (flow
aids) and lubricants to
ensure efficient tabletting; disintegrants to
promote tablet break-up in the digestive tract;
sweeteners or flavours to enhance taste; and
pigments to make the tablets visually attractive
or aid in visual identification of an unknown
tablet. 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.
Medicinal tablets were originally made in the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 distinguish different
medicines. Tablets are often imprinted with
symbols, letters, and numbers, which allow them
to be identified, or a groove to allow splitting
by hand. Sizes of tablets to be swallowed range
from a few millimetres to about a centimetre.
The compressed tablet is the most commonly seen dosage
form in use today. About two-thirds of all prescriptions are
dispensed as solid dosage forms, and half of
these are compressed tablets. 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.
The tablet is just one of the many forms that an
oral drug can take such as syrups, elixirs, suspensions,
and emulsions.
History
Pills are thought
to date back to around 1500 BC.[1] Earlier
medical recipes, such as those from 4000 BC,
were for liquid preparations rather than solids.[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. In ancient Greece, such medicines were
known as katapotia ("something to be
swallowed"), and the Roman scholar Pliny, who
lived from 23 to 79 AD, first gave a name to
what we now call pills, calling them pilula.[1]
Pills have always
been difficult to swallow, and efforts have been
made to make them go down easier. In mediaeval
times, people coated pills with slippery plant
substances. 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
the 1800s, sugar coating and gelatin coating
were invented, as were gelatin
capsules.[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". The device was
capable of compressing powder into a tablet
without the use of an adhesive.[2]
