Tablet is the most common and convenient dosage form. It contains active ingredient(s) and excipients. The various types of tablets are described as follows:
Compressed Tablets
In addition to the API(s), compressed tablets usually
contain a number of pharmaceutical excipients, including diluents or fillers, binders
or adhesives, disintegrants or disintegrating agents, anti-adherents, glidants,
and lubricants to prepare the tablets of the desired size and function.
Multiple Compressed Tablets
Multiple compressed tablets are prepared by subjecting the
fill material to more than a single compression. The result may be a
multiple-layer tablet or a tablet within a tablet, the inner tablet being the
core and the outer portion being the shell.
Sugar-coated Tablets
Compressed tablets may be coated with a colored or an
uncolored sugar layer. The coating is water soluble and quickly dissolves after
swallowing. The sugar coat protects the enclosed drug from the environment and
provides a barrier to objectionable taste or odor.
Film-Coated Tablets
Film-coated tablets are compressed tablets coated with a
thin layer of a polymer capable of forming a skin-like film. The film is
usually colored and has the advantage over sugar coatings in that it is more
durable, less bulky, and less time-consuming to apply.
Gelatin-Coated Tablets
A recent innovation is the gelatin-coated tablet. The
innovator product, the gel-cap, is a capsule-shaped compressed tablet that
allows the coated product to be about one-third smaller than a capsule filled
with an equivalent amount of powder. The gelatin coating facilitates
swallowing, and gelatin-coated tablets are more tamper evident than unsealed
capsules.
Enteric-Coated Tablets
Enteric-coated tablets have delayed-release features. They
are designed to pass unchanged through the stomach to the intestines, where the
tablets disintegrate and allow drug dissolution and absorption and/or effect.
Enteric coatings are employed when the drug substance is destroyed by gastric
acid or is particularly irritating to the gastric mucosa or when bypass of the
stomach substantially enhances drug absorption.
Buccal and Sublingual Tablets
Buccal and sublingual tablets are flat, oval tablets
intended to be dissolved in the buccal pouch (buccal tablets) or beneath the
tongue (sublingual tablets) for absorption through the oral mucosa. They enable
oral absorption of drugs that are destroyed by the gastric juice and/or are
poorly absorbed from the gastrointestinal tract.
Chewable Tablets
Chewable tablets, which have a smooth, rapid disintegration
when chewed or allowed to dissolve in the mouth, have a creamy base, usually of
specially flavored and colored mannitol.
Effervescent Tablets
Effervescent tablets are prepared by compressing granular
effervescent salts that release gas when in contact with water.
Molded Tablets
Certain tablets, such as tablet triturates, may be prepared
by molding rather than by compression. The resultant tablets are very soft and
soluble and are designed for rapid dissolution.
Tablet Triturates
Tablet triturates are small, usually cylindrical, molded, or
compressed tablets containing small amounts of usually potent drugs. Today,
only a few tablet triturate products are available commercially, with most of
these produced by tablet compression.
Immediate-Release Tablets
Immediate-release tablets are designed to disintegrate and
release their medication with no special rate-controlling features, such as
special coatings and other polymer matrix forming techniques.
Rapidly Disintegrating or Dissolving Tablets
Rapid-release tablets (rapidly dissolving tablets or RDTs)
are characterized by disintegrating or dissolving in the mouth within 1 minute,
some within 10 seconds.
Extended-Release Tablets
Extended-release tablets (sometimes called
controlled-release tablets) are designed to release their medication in a
predetermined manner over an extended period.
Vaginal Tablets
Vaginal tablets, also called vaginal inserts, are uncoated, bullet-shaped,
or ovoid tablets inserted into the vagina for local effects.
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