Tablet is a solid dosage form each containing a standard unit dose of one or more medicaments/Ingredients. Tablets are intended for oral administration. There are many types of Tablets are available Some tablets are swallowed whole or after being chewed, some are dissolved or dispersed in water before administration, and some are retained in the mouth where the active ingredient is liberated.
Preparations intended for administration by other routes, for example, in the form of implants and pessaries, may also be presented in the form of tablets but because they may require special formulations, method of manufacture or form of presentation appropriate to the particular use they may not comply with all the requirements of tablet’s standards.
TYPES OF TABLETS
General Physical specifications & characteristics: Tablets are solid, right circular cylinders, the end surfaces of which are flat or convex and the edges of which may be bevelled. They may exist in other shapes like triangular, rectangular, etc also. They may have lines or break-marks and may bear a symbol or other markings which are called a scored tablet. They are sufficiently hard to withstand handling without crumbling or breaking while packaging and consuming.
Uncoated tablets are all single-layer and multi-layer tablets resulting from a single compression of particles. Multi-layer tablets consisting of parallel layers obtained by successive compression of particles of different compositions or colour. On Uncoated tablets no external treatment is applied, there remains such tablets as after compression.
There are not any added substances are applied specifically intended to modify the release of their active ingredient(s) in the digestive fluids. No external layers of colours are applied to such tablets.
The addition of colouring to uncoated tablets other than multi-layer tablets is not permitted. This type of tablets has the general characteristics of tablets.
Coated Types of Tablets:
Coated tablets are tablets covered with one or more layers of mixtures of various substances such as resins, gums, inactive and insoluble fillers, sugars, plasticisers, polyhydric alcohols, waxes, etc.
This types of tablets are most popular in the industry. Film-coated tablets claim more than 60% total production of tablets in the world. Film-coated tablets are shining and look beautiful visually. They are easy to take orally because their film layers mask the bitter taste and can swallow easily.
Types of Film coating on Tablets
There are lots of color materials are used in film-coated tablets like Titanium Dioxide, Sunset yellow, Brilliant blue tec. There are two types of film-coating, one is aqueous film coating when water is used as a solvent with coating materials, and the other is non-aqueous film coating where organic solvent Iso Propyl Alcohol is used as a solvent.
The coating may also contain medicaments in some cases. In compression-coated tablets, the coating is applied by compressing around the tablets granules prepared from tablet excipients such as lactose, calcium phosphate, etc.
Substances used as coatings are usually applied as a solution or suspension in the coating pan and autocota machines, these days coating becomes very easy and fast in autocota machine where a very thin and smooth layer is applied on tablet’s surface. When the coating is thin, the tablets are described as film-coated.
Coated tablets have a smooth, usually polished and often coloured, surface; a broken section examined under a lens shows a core surrounded by one or more continuous layers of a different texture.
There are lots of colours used in tablet coating main are Titanium Dioxide, Sunset Yellow, Carmoisine, Erythrosine, Ponceau-4R, Brilliant Blue, Tartrazine. Many more colour texture can be created by mixing these colour in different ratios.
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Enteric-coated tablets (Gastric-resistant tablets) are tablets covered with one or more layers of coatings intended to resist the gastric fluid but to release their active ingredient(s) in the intestinal fluid.
Enteric coating is done with cellulose acetate phthalate and anionic copolymers of methacrylic acid. Ethers of acetate phthalate and anionic copolymers of methacrylic acid are used for providing tablets with a gastric-resistant coating.
Enteric-coated tablets are mainly antacid tablets of Pantoprazole, Rabeprazole, Lansoprazole, and Esomeprazole. The action of these tablets is designed in such a manner that they get dissolve in intestinal fluid.
Dispersible tablets are uncoated tablets that produce a uniform dispersion in water and may contain permitted coloring matter and flavoring agents.
Dispersible tablets are largely used for children to mask the bitter taste of ingredients, children usually do not like to swallow bitter tablets, the bitter tablet can enhance the possibility of vomiting in children.
This type of tablets is very fast in dissolving in cold water. They should comply with the dispersion test as per standard.
Modified-release tablets (Sustained-release tablets) are coated or uncoated tablets containing auxiliary substances or prepared by procedures that, separately or together, are designed to modify the rate or the place at which the active ingredient is released.
Modified-release Tablets are also known as Extended-Release Tablets where the release of ingredient in the stomach set to release over the Pan of 24 hours so that patients can get a dose of ingredient in a staggered manner. This type of tablet is Voveran-SR, Tramadol 100mg SR Tablets are a few general examples.
Modified-release Tablets are also as Immediate-Release Tablets. These tablets are intended to release fast in the stomach so that their action can be utilized immediately in the human body.
Soluble tablets are usually uncoated tablets that are intended to dissolve in water. The resulting solution may be slightly opalescent and muddy due to added excipients used in the manufacturing of the tablets.
Effervescent tablets are uncoated tablets generally containing acidic substances and carbonates or bicarbonates which have a property to react fast in the presence of water to release carbon dioxide. They are intended to be dissolved or dispersed in water before administration. Example Histac Tablet. Such types of tablets are used for instant results.
Subligual and Lonzenges Tablets: :
Sublingual (SL) meaning the Latin word for “under the tongue”, SL refers to the pharmacological route of administration a tablet by which the tablet’s ingredient diffuses into the blood through tissues, under the tongue which is predominantly a mucous gland that produces a thick mucinous fluid and lubricates the oral cavity which allows for swallowing, initiating digestion, buffering pH, and dental hygiene.
Tablets for use in the mouth are usually uncoated tablets formulated to be chewed or to effect a slow-release and local action of the active ingredient (lozenges) or the release and absorption of the active ingredient under the tongue (sublingual tablets). Chewable tablets and lozenges may have flavoring agents.
What is the principle of Sublingual:
When a chemical (In form of a Tablet) comes in contact with the mucous membrane beneath the tongue, it is absorbed by tissues present under the tongue. This is called a sublingual manner. The connective tissue beneath the epithelium contains a profusion of capillaries, then substance present in tablets diffuses into them and enters the venous circulation. However, the substances absorbed in the intestines are subject to the first-pass metabolism in the liver before entering the general circulation.
All forms of in Sublingual Preparations:
- Sublingual tablets—Tablets that easily melt in the mouth, dissolve rapidly and with little or no residue. Nitroglycerine tablets are an example, the anti-emetic ondansetron is another, Such types of tablets are used for very special conditions.
- Sublingual strips—similar to tablets in that they easily melt in the mouth and dissolve rapidly. Suboxone is an example of a medication that comes in a sublingual strip. Sublingual strips have a mechanism of fast-acting effectiveness and discreetness. Sublingual cannabis and Marijuana strips interact with the body’s oral mucosa in absorbent membranes under the tongue reach in the blood faster than the oral route, Those sublingual membranes are tough.
- Multi-purpose tablets—There are some soluble tablets that have multiple options for administration, either oral or sublingual (or buccal) administration, often also suitable for the preparation of injections, Hydrostat (hydromorphone) and a number of brands of morphine tablets and cubes are an example of Multi-purpose tablets.
- Sublingual drops—A concentrated solution to be dropped under the tongue which is intended to penetrate in mucous membrane beneath of the tongue, as an example of some nicocodeine cough preparations. Moreover, the allergen is given to kids by placing it under his tongue, that’s called sublingual immunotherapy (SLIT). Unlike antihistamines and other medications that treat allergy symptoms, immunotherapy treats the condition itself.
- Sublingual spray— This form of Sublingual is sprayed under the mucous membrane of the tongue for the faster effect of enabling the drug. Which is absorbed directly through the mucous membrane under the tongue? The sprays for the tongue are certainly human and veterinary drugs are dispensed as such under the tongue.
- Lozenge—effects a metered and patient-controlled-rate combination of sublingual, buccal, and oral administration, as with the Actiq fentanyl lozenge-on-a-stick (lollipop). However, the shape of such types of tablets may be different from the usual tablet’s shapes.
- Effervescent buccal—This method drives the drug through the mucous membranes much faster.Classical example Fentanyl effervescent buccal tablet (FEBT) is designed in such a manner so that it can enhance the rate and extent of the absorption of fentanyl (an opioid drug) through the buccal mucosa part of the human tongue.
HOW ARE TABLETS MANUFACTURED?
Tablets are manufactured by compression of uniform volumes of powders or granules by applying high pressures and using punches and dies.
The particles are compressed consist of one or more medicaments/ Ingredients, sometimes auxiliary substances such as diluents, binders, disintegrating agents, lubricants, glidants are used in the compression process, these substances are capable of modifying the behavior of the medicaments/ Ingredients in the digestive tract.
However, such substances must be innocuous and therapeutically inert in the quantities present.
There are several types of tablets. Tablets present a variety of characteristics and consequently because of their composition, method of manufacture, or intended use. Like Coated tablets, uncoated tablets, film-coated tablets, sugar-coated tablets.